Another is the matching law in the experimental analysis of behavior. ... most central to science is causal expla- natio
The Behavior Analyst
2000, 23, 173-190
No. 2 (Fall)
Varieties of Scientific Explanation J. Moore University of Wisconsin-Milwaukee Scientific explanations often take one of two forms. The first is instantiation. According to this form, an event is said to be explained when it can be expressed as some particular value of a variable in a general proposition, equation, or law. One example of instantiation in psychology is Stevens' psychophysical law. Another is the matching law in the experimental analysis of behavior. A second form of explanation is a deduction from a covering law. According to this form, an event is said to be explained when its description follows as a valid logical deduction in an argument that has a covering law as one premise and a statement of antecedent conditions as another premise. Examples of covering law explanations in psychology are found in traditional neobehaviorism, which sought to develop laws of behavior so that observed behavioral events could be explained as deductions therefrom. Strictly speaking, neither form of explanation is consistent with behavioranalytic explanations derived from Skinner's radical behaviorism, which emphasize the pragmatic sources and contributions of the verbal behavior regarded as explanatory. Key words: explanation, instantiation, covering law, radical behaviorism, methodological behaviorism, verbal behavior
Etymologically, the word explanation is derived from the Latin explanare, meaning to make plain or flatten out. Beyond that, the term has been used in many different ways, with many different meanings, by many different theorists. Braithwaite's (1953) definition is representative and not entirely whimsical: "An explanation, as I understand the use of the term, is an answer to a 'Why?' question which gives some intellectual satisfaction" (pp. 348-349). In any event, perhaps the concern with explanation that is most central to science is causal explanation. For example, according to Wallace (1972),
The present article will critically examine the topic of explanation, focusing on causal explanation. The article will note two dominant forms of explanation, primarily in traditional psychology, but also in the experimental analysis of behavior. It will then offer a behavior-analytic interpretation of various explanatory practices.
TWO FORMS OF TRADITIONAL EXPLANATION Turner (1967, p. 178) has noted that in much of contemporary science, explanations tend to take one of two forms: (a) explanation by what will here be called "instantiation," and (b) Scientia est cognitio per causas. [Science is knowledge through causes.] ... The early un- explanation by deduction from a "covderstanding of science-from which the modem ering law." In each case, the phenomnotion grew-was that it must be concerned enon that is to be explained is an with a search for causes. And the explanations "event."
for which science was ultimately searching, from its beginnings among the Greeks ..., were causal explanations. (p. 6)
Portions of this article were presented at conferences of the Behavior Analysis Association of Michigan, Ypsilanti, March 1997, and the Association for Behavior Analysis, Chicago, May 1997. Correspondence concerning this article should be addressed to J. Moore, Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (E-mail: jcm@ uwm.edu).
Explanation by Instantiation According to instantiation, an event is said to be explained when its features are symbolically described using some particular value of a parameter in a more general statement, such as a proposition, equation, mathematical model, or law. Instantiation is commonly regarded as a lower level of explanation. It presumably gets its name
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because the event to be explained is regarded as a specific instance that concretely illustrates the more abstract statement. Prediction is accommodated in the sense that one is able to predict that instances of the data can be described by deploying particular values of the parameters in the more general statement, rather than in the sense that a specified cause will produce a specified effect. The psychophysical law of Stevens illustrates this form of explanation in psychology. Stevens spent much of his distinguished scientific career developing and validating a formal mathematical description of the relation between (a) the "objective," physical magnitude of stimuli (e.g., how intense a light was), as measured using the instruments of physics; and (b) the numbers people reported as representing the "subjective" magnitude of the stimulus, presumably derived from some personal "scale value" of the magnitude of the sensation they experienced when presented with the objective stimulus. The equation that Stevens (1957) developed was T = kSn, known as the psychophysical law. In this equation, T represents the strength of the psychological, subjective sensation; k is an individual difference parameter; S is the actual magnitude of the physical stimulus, measured objectively as the physicist would measure it; and the exponent n is the term that relates the subjective estimate of the stimulus to its objective measure. An event, or any particular instance of data reported from a subject, was described by particular values of the variables, but the form of the equation was what was regarded as important, rather than the particular values of the variables (except perhaps for n, corresponding to the subject's sensitivity to the stimulus in that modality). This work was consistent with Stevens' earlier assertion that "Science seeks to generate confirmable propositions by fitting a formal system of symbols (language, mathematics, logic) to empirical observations" (Stevens, 1939, p. 222).
Historically, Stevens' mode of research found favor with much of the community of experimental psychologists. For example, Boring (1950, p. 656) hailed Stevens for leading the operational movement in the Harvard department and American psychology generally, because Stevens ostensibly showed that at last there was an "operational" way to deal "scientifically" with such "subjective" topics as sensation in terms of objective and publicly observable measures, without resorting to the vagaries of introspection. Indeed, in recognition of Stevens' extensive influence, Killeen (1976) later extolled the merits of Stevens' methods for the experimental analysis of behavior, for example, with regard to the scaling of reinforcement value. Moreover, as will be seen later in the present article, Stevens' mode of research has proven to be enormously influential among many members of the Harvard department as they investigated the distribution of responding on concurrent schedules and formulated the matching law.
Explanation by Deduction from a Covering Law The second form of explanation involves deductions from a covering law (Hempel & Oppenheim, 1948; see also discussions in Pitt, 1988, and Salmon, 1984, 1989, which are the basis for most of what follows). This form is commonly regarded as a higher level of explanation than instantiation. According to this form of explanation, an event is said to be explained when its description follows as a valid deduction in a logical argument in which at least one of the premises is a covering law and at least one of the other premises is a statement of antecedent conditions. Covering law explanations presumably get their name because the law "covers" the event to be explained, by subsuming it under (e.g., as a consequence of) the law. Covering law explanations have several subtypes, but an exhaustive treatment of
SCIENTIFIC EXPLANATION those subtypes is somewhat technical and beyond the scope of the present article. Suffice it to say that to the extent specified by the covering law, which may be deterministic or stochastic, covering law explanations typically mediate prediction in the conventional sense of cause and effect, rather than in the sense that researchers can predict that the data will conform to a generalized equation or law with parameters to address individual instances. The structure of the logical argument illustrating covering law explanations is as follows (e.g., Turner, 1967, p. 275): Cl, C2, C3, . . , Cn Statement of antecedent conditions
LI, L2, L3, . E
. .,
Ln Covering law [universal! general law(s) or statistical law(s)] Description of empirical phenomenon to be ex-
plained
Suppose one is interested in explaining why a piece of wood floated when it was placed on water. The antecedent condition is that the piece of wood is less dense than water. The covering law is that any solid body that is less dense than a liquid will float when placed on the liquid. The conclusion providing the explanation is the description of the observed state of affairs: that the wood (the solid) floated when placed on the water (the liquid). A noteworthy feature of covering law explanations is the symmetry of description, prediction, and explanation. That is, if the conclusion of the argument is a description of an event that has already happened, the past tense is used in conjunction with the to-be-explained event, and we speak of explaining the event. If the conclusion of the argument refers to some event that has not yet happened, but will happen if the noted conditions obtain, the future tense is used, and the event is said to be predicted. Note that the fundamental structure of the argument remains the same throughout, regardless
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roles of either (a) the conclusion as description or (b) conclusion as prediction can even be reversed relative to (c) the statement of the antecedent condition, without any loss of explanatory or predictive power. Historically, covering law explanations found great favor among midcentury traditional neobehaviorists. For example, Kendler and Spence (1971) endorsed the deductive, covering law model of explanation quite explicitly: The neobehavioristic decision concerning the nature of explanation is, in principle, both clear and simple. Explanation is equated with theoretical deduction: an event is explained by deducing it from one or more general propositions. The deductive process is analogous to mathematical proof although its precision can vary from mathematical verification to the logical use of ordinary language. (p. 21)
Indeed, the covering law model remains the model of explanation for a large part of the scientific community. One has only to look at the literature in virtually any discipline to see the emphasis on proposing a law that predicts a given effect, and then accounting for a broad range of observed phenomena in terms of deductions from this law. Perhaps that is why the formulation of a law or theory, from which one may deduce testable predictions, is conventionally given such honorific status in science.
BEHAVIOR-ANALYTIC EXPLANATORY PRACTICES Explanation As the Result of Verbal Processes How then do behavior analysts view the issue of explanation? In addressing this question, Day (1969a) rhetorically inquired whether explanations and predictions are properties of scientific systems in themselves or whether they are aspects of human functioning. Are predictions about what is to be observed properties of formally organized words and symbols or are they varieties of human behavior? ... For Skinner, the preference is to view explanations and predictions as aspects of human behavior. ( p. 504)
of whether the argument is called an explanation or prediction. Indeed, the The present argument is that behavior
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analysts view explaining and predicting as aspects of human verbal behavior. As such, critical questions about explanation are engaged in the same way as critical questions about other forms of complex operant behavior: in terms of contingencies. For example, what discriminative stimuli occasion the explanation, and what reinforcers support the explanation? As Skinner (1945) put it in emphasizing the behavior-analytic treatment of explanation in terms of verbal processes, A considerable advantage is gained from dealing with [explanatory] terms, concepts, constructs, and so on, quite frankly in the form in which they are observed-namely, as verbal responses. There is then no danger of including in the concept that aspect or part of nature which it singles out. (p. 271)
Let us now attempt to analyze the contingencies that participate in the verbal processes of explanation.
The Continuity of Scientific Activity What discriminative stimuli occasion explanatory activity? The matter is complex, because Skinner's (1957) comments of over 40 years ago are probably still valid: The verbal processes of logical and scientific thought deserve and require a more precise analysis than they have yet received. One of the ultimate accomplishments of a science of verbal behavior may be an empirical logic, or a descriptive and analytical scientific epistemology, the terms and practices of which will be adapted to human behavior as a subject matter. (p. 431)
We may note that from the perspective of behavior analysis, there is not one unique activity that constitutes science. Rather, there are several, and they are continuous. For example, in one passage describing the continuity of scientific activity, Skinner (1953) wrote that science is a search for order, for uniformities, for lawful relations among the events in nature. It begins, as we all begin, by observing single episodes, but it quickly passes on to the general rule, to scientific law. ... Science sharpens and supplements this experience by demonstrating more and more relations among events and by demonstrating them more and more precisely. As Ernst Mach showed in tracing the history of the
science of mechanics, the earliest laws of science were probably the rules used by craftsmen and artisans in training apprentices. The rules saved time because the experienced craftsman could teach an apprentice a variety of details in a single formula. By learning a rule the apprentice could deal with particular cases as they arose. In a later stage science advances from the collection of rules or laws to larger systematic arrangements. Not only does it make statements about the world, it makes statements about statements. It sets up a "model" of its subject matter, which helps to generate new rules very much as the rules themselves generate new practices in dealing with single cases. A science may not reach this stage for some time. (pp. 13-14)
In another passage concerned with the continuity of scientific activity, Skinner (1972, pp. 305 ff.) wrote that three important steps occur in the development of theoretical explanations. The first step is to identify the basic data. This step is surprisingly difficult, and many sciences have started off on the wrong foot precisely because they have incorrectly specified their basic data. The second step is to express uniform relations among the data. The expression of these relations typically takes the form of the laws of the science. The third step is to develop abstract concepts. Skinner identified acceleration and force from Mach's (1883/ 1974) Science of Mechanics as relevant examples. These concepts are something more than the second-step laws from which they are derived. These concepts "are peculiarly the product of theory-making in the best sense, and they cannot be arrived at through any other process" (Skinner, 1972, p. 307). They help the scientific explanation go beyond the expression of uniform relations by providing "a formal representation of the data reduced to a minimal number of terms" (Skinner, 1950, p. 216). Given the multiplicity and continuity of scientific activity described above, behavior analysts suggest that the first-stage activity of a scientific explanation of behavior-identifying the basic data-is therefore to specify the
SCIENTIFIC EXPLANATION elements of the environment with which the organism is interacting. This stage involves accepting behavior as a subject matter in its own right, and not as an indicator of things going on in other dimensions. These interactions, then, constitute the discriminative stimuli for this initial stage of explanatory activity. The second and higher stages involve organizing behavioral observations according to the Darwinian metatheoretical principle of selection by consequences, which is then applied comprehensively to the life activities of organisms (see Catania & Hamad, 1988, pp. 11-76). These observations are organized at one or more of three levels: (a) the contingencies of survival that have selected the physiological and innate behavioral characteristics through the evolution of the species, (b) the contingencies of reinforcement that have selected an operant behavioral repertoire and the contingencies of stimulus association that have yielded a respondent behavioral repertoire during the lifetime of the individual organism, and (c) the contingencies of reinforcement that have selected the practices of the culture in which the individual lives. The earlier statements about the elements of the environment with which an organism interacts are the discriminative stimuli that occasion activity at these levels. Explanations that incorporate contingencies and selection by consequences ultimately reflect uniformities across many different circumstances, using a minimum number of concepts. For example, when asked whether the term explanation was a meaningful term as it related to behavior-analytic practices (presumably, the to-be-explained behavior in this case was operant behavior, acquired during the lifetime of the individual organism, identified in Level b above), Skinner (1964) once answered "When I said 'explanation,' I simply meant the causal account. An explanation is the demonstration of a functional relationship between behavior and manipulable or
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controllable variables" (p. 102). As may be inferred from the foregoing comment, then, in a large number of cases, the to-be-explained behavior, either operant and respondent, is acquired during the lifetime of an organism. Suppose it is operant behavior. In that case, we say that the explanation is occasioned by the familiar interrelation among discriminative stimulus, response, and reinforcer that controls the behavior being observed. What then about the reinforcers for the various explanatory activities? The reinforcers for explanatory verbal behavior presumably range from outcomes achieved via the direct manipulation of environmental events (e.g., control), to predictions and interpretations when direct manipulation is not feasible, to codifying uniformities, to aiding in the ordering of confusing data, to simply resolving puzzlement (e.g., Skinner, 1979, p. 282). Explanatory statements may, therefore, start out as basic cause-and-effect first-level statements, but then evolve into other statements at the second and higher levels to be something more. The firstlevel statements are presumably reinforced directly through the control achieved by direct manipulation. The higher level statements are reinforced by the more subtle outcomes, such as achieving order and resolving puzzles, in addition to anything achieved through prediction and control. The Dimensions of Explanatory Practices To recapitulate, the present argument is that the specification of causes and effects in terms of functional relations constitutes the basis for higher order scientific statements. Nevertheless, the specification of functional relations involves a consistent level of observation and analysis, and the higher order statements do not create other dimensions that need to be included in the behavioral account. Behavior, in particular, is explained at the level of behavior, that is, at the level of the operations
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and prevailing stimulus conditions that impinge upon the organism and that may be considered as responsible for the behavior in question. Reductionism, for example, by reducing behavioral events to physiological events, does not constitute an explanation of the response in the sense meant here. Similarly, mentalism consists in proposing events in a "higher" dimension (e.g., mental, psychic, spiritual, conceptual) as responsible for the behavior in question. As reviewed by Moore (1981, 1990a), mentalistic verbal behavior is controlled by a variety of conditions that are not associated with or derived from observed events, and mentalistic verbal behavior explains nothing. Indeed, it interferes with coming into contact with the factors that actually are causing the behavior. Hence, behavior analysis explains the actions of an organism by locating those actions "in a frame of reference provided by the [organism] itself or by various external objects or fields of force" (Skinner, 1938, p. 6). Multiple Control of Scientific Verbal Behavior An important concern here is whether many current theories and explanations in psychology have gone through anything remotely resembling the sort of developmental process, three steps or otherwise, described in Skinner's writings. On the present view, they have not. Rather, the argument is that many current theories and explanations are controlled to a large extent by factors that are cherished for irrelevant and extraneous reasons. They are the product of many mentalistic or even dualistic factors, of unfortunate metaphorical extensions, and so on. As a result, the stimulus control over what are hailed as advanced theoretical and explanatory activities is suspect. On a behavior-analytic view, the necessary base needs to be established before useful third-step concepts and explanations will appear, and the mentalistic tradition in psychology is so strong
that psychology has not gone through the necessary prior steps to establish that base. Alternatively stated, we can see that verbal behavior regarded as explanatory is often under "multiple control" (Skinner, 1957, pp. 227 ff.). As Moore (1981) noted, some of the stimulus control derives from experimental operations and contacts with data. Other control derives from other sources. For example, some explanatory verbal behavior simply manifests "control by ordinary language habits, extensive chains of familiar intraverbals, and one or another preconception about the inherent nature of scientific explanation" (Day, 1969b, p. 323; see also Moore, 1990b). As Day (1969b, p. 319) stated it, the traditional conception assumes that the chief function of language is to identify the Platonic nature of the thing spoken about. It assumes that any time we do speak, the words we use must be things that refer to other things in the world at large that have actually been declared as metaphysically real and permanent, by virtue of the inherent properties that give the things their essential identities. Speakers then assume they have correctly isolated the things talked about. At best, such reification only illustrates the "formalistic fallacy" (Skinner, 1969, p. 265; see also the discussion of "realism" in Moore, 1998, p. 220). Other explanatory verbal behavior manifests control by metaphors and social or cultural factors that are cherished for irrelevant and extraneous reasons. Although he was neither a radical behaviorist nor a behavior analyst, Kantor (1938) characterized the problem as follows: We may, however, demand that all [explanatory verbal behavior] be connected with the primary data or events by a substantial link of observation and observational procedure.... The exigencies of scientific work may be such as to attenuate the thread binding the construction with events to a very thin calibre. ... But it is an established maxim that this thread can never be broken. When the ratio of construction to observation is very large we may still regard the speculative construction as scientific, but when
SCIENTIFIC EXPLANATION the observational factor is zero we have no other alternative than to characterize the speculation as unscientific or non-scientific. (pp. 11-12)
Kantor (1945) continued on this same theme by noting that "The lesson is plain-namely, by the frail process of language manipulation ideas are established with which no scientific enterprise is in any manner concerned," to which he added the following footnote: "Excepting, of course, the psychological and cultural investigation of the origin and maintenance of such theories" (p. 148). In sum, behavior analysis is concerned with the contingencies that are responsible for a given instance of verbal behavior and the contingencies into which the verbal artifact subsequently enters as it exerts discriminative control among those who entertain it. The argument is that we must strip away control arising from mischievous social and cultural contingencies, leaving only the factors producing such things as manipulation and control, to understand the validity of a scientific explanation. With regard to the multiple control over scientific verbal behavior, Skinner (1957) put it as follows: The scientific community encourages the precise stimulus control under which an object or property of an object is identified or characterized in such a way that practical action will be most effective.... Generic extensions are tolerated in scientific practice, but metaphorical, metonymical, and solecistic extensions are usually extinguished or punished. Metaphorical extension may occur, but either the controlling property is quickly emphasized by additional contingencies which convert the response into an abstraction or the metaphor is robbed of its metaphorical nature through the advent of additional stimulus control. ... In ruling out the effects of other consequences of verbal behavior the contingencies established by the scientific community work to prevent exaggeration or understatement, misrepresentation, lying, and fiction.... Scientific verbal behavior is most effective when it is free of multiple sources of strength; and humor, wit, style, the devices of poetry, and fragmentary recombinations and distortions of form all go unreinforced, if they are not actually punished, by the scientific community. ... In general, however, practices are designed to clarify the relation between a verbal response made to a verbal stimulus and the nonverbal circumstances responsible for it. The community is
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concerned with getting back to the original state of affairs and with avoiding any distortion due to the intervening verbal linkage. (pp. 419-420)
The Role of the Unobserved What then about the role of the unobserved? In point of fact, one of the distinctive features of behavior analysis is its position on the unobserved: Behaviorists have, from time to time, examined the problem of privacy, and some of them have excluded so-called sensations, images, thought processes, and so on, from their deliberations. When they have done so not because such things do not exist but because they are out of reach of their methods, the charge is justified that they have neglected the facts of consciousness. The strategy is, however, quite unwise. It is particularly important that a science of behavior face the problem of privacy. It may do so without abandoning the basic position of behaviorism. Science often talks about things it cannot see or measure. ... An adequate science of behavior must consider events taking place within the skin of the organism, not as physiological mediators of behavior, but as part of behavior itself. It can deal with these events without assuming that they have any special nature or must be known in any special way. The skin is not that important as a boundary. Private and public events have the same kinds of physical dimensions. (Skinner, 1969, pp. 227-228).
As suggested above, Skinner wrote numerous times about the importance of private events (e.g., Skinner, 1953, chap. 17 on "Private Events in a Natural Science"; Skinner, 1957, chap. 19 on "Thinking"). Expositions of these writings are available elsewhere (e.g., Moore, 1992) and need not be reviewed here. Two important considerations are that (a) some factor need not be regarded as from another dimension just because it is unobserved, owing to the current state of our technology; and (b) the factor need not be incorporated into a scientific explanation in a special way. There is no other dimension that requires such factors to be treated in a special way. Skinner (1945) argued that there were four means by which the influence of private events can be understood as arising from public circumstances. Thus, a critical feature is not so much how many people can observe a cause of behavior, but whether
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any cause is held to be from the behavioral dimension or from another dimension, such as the mental, psychic, or conceptual dimension. In sum, it is clear that behavior analysis has always considered causal factors that are not publicly observed (see also Moore, 1984). It does consider them differently than does traditional psychology, however. Behavior analysis formulates their contribution at a descriptively consistent level, whereas traditional psychology conceives of the factors as from a different dimensional system (e.g., Skinner, 1950, p. 193).
The Contribution of Physiology To be sure, the behavior-analytic stance on the importance of behavioral contingencies in explanations does not mean that physiology is irrelevant in a science of behavior (see also Moore, 1990a). Physiological phenomena concern the two unavoidable temporal gaps in a behavioral account. The first gap is between behavior and the variables of which it is a function, as the behavior takes place. The second gap is between the experiences of an organism in its surrounding circumstances and any resulting changes in its behavior, as that behavior is observed in the future. Information about the events that take place during these gaps will be provided by physiologists, rather than psychologists, although psychologists might inform the physiologists of the factors for which they should look (e.g., Catania & Hamad, 1988, p. 470). However, only the science of physiology can fill those two gaps. In doing so it provides additional information that will guide efforts to predict and control behavior. Physiological information is not necessary for a more valid account of behavior as a process. That would be reductionistic, and may be rejected. The following passage from Skinner (1972) illustrates the behavior-analytic perspective:
continuity between input and output will not eventually be established. The genetic development of the organism and complex interchanges between organism and environment are the subject matters of appropriate disciplines. Some day we shall know, for example, what happens when a stimulus impinges upon the surface of an organism, and what happens inside the organism after that, in a series of stages the last of which is the point at which the organism acts upon the environment and possibly changes it.... But all these inner events will be accounted for with the techniques of observation and measurement appropriate to the physiology of the various parts of the organism, and the account will be expressed in terms appropriate to that subject matter. It would be a remarkable coincidence if the concepts now used to refer inferentially to inner events were to find a place in that account. (pp. 269-270)
Behavior analysis and physiology therefore provide reciprocal support for each other; physiology does not provide the logical grounds for validating behavior-analytic explanations. Behavior analysis and a theoretical behavioral neuroscience are therefore complementary sciences. In a more practical vein, physiological information, such as how an organism has been changed by interactions with its environment, can compensate for a possibly inadequate behavioral specification of those interactions as a basis for making predictions. Overall, behavior analysis gives neuroscience one of its directions, just as Mendel's studies of the numerical relations among the traits of successive generations of pea plants gave the study of the gene one of its directions (Catania & Harnad, 1988, p. 470). Pragmatism
Pragmatism can be defined as the general position that the utility of an idea is the best criterion for determining its validity. On the present view, pragmatism emphasizes that if a particular explanation proves valuable, the contingencies underlying the development and application of the explanation in question need to be critically examined. This sort of examination This does not mean, of course, that the organ- would preclude a tacit commitment to ism is conceived of as actually empty, or that a facile realism, which would hold that
SCIENTIFIC EXPLANATION
just because an explanation "works" to some approximation, the explanation must have identified something essentially "real" in the world at large and science should go off hunting for it. That unfortunate problem is reification, and is one that Skinner (1945, p. 271) warned against. This sort of examination would also preclude a tacit commitment to instrumentalism, which would hold that invoking "explanatory fictions" is justified if they allow one to predict something about an event to some approximation. The present view is that a critical examination of contingencies would reveal how and to what extent verbal behavior that successfully guides future actions is derived from contacts with events, so that scientists do not subsequently make various kinds of errors (for additional discussion of instrumentalism and the contrasting position of realism, see Moore, 1998, pp. 220-222).
Alternative Interpretations of BehaviorAnalytic Explanatory Practices
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scientific method is concerned, the system set up in the preceding chapter may be characterized as follows. It is positivistic. It confines itself to description rather than explanation" (p. 44). Moreover, Coleman (1987) has documented the essentially descriptive quantitative nature of Skinner's early research program. Largely as the result of Skinner's early writings, then, his system was deemed an atheoretical "descriptive behaviorism" for many years (e.g., Kendler & Spence, 1971; Marx, 1951, p. 393). Nevertheless, the present argument is that explanation may indeed be meaningfully distinguished from description. More specifically, the present argument is that when people describe an event, they tact the presence of a response, including perhaps its topographical characteristics, and the presence of certain stimuli, including perhaps their physical characteristics. This activity is necessary for higher stage explanations, but is not equivalent to them. In contrast, when people explain something, they at least tact the functional relation between classes of responding and classes of the surrounding stimulus conditions, and engage in further autoclitic manipulation of those tacts into a system. To be sure, the distinction between description and explanation proposed above can become tenuous, because one might say that an explanation describes a functional relation, and to say when a description becomes an explanation is often a matter of the discriminations established during a speaker's personal history. Nevertheless, the distinction seems to be worth preserving. Behavior-analytic explanations are often challenged by traditional psychologists as well. For example, a common challenge is that Skinner's system merely describes-it does not explain. In this regard, Kendler and Spence (1971) have argued on the basis of Skinner's (1950) rhetorical rejection of traditional theories as follows:
The present analysis differs somewhat from other interpretations of behavior-analytic explanatory practices. For example, Baum (1974a) writes, "With Skinner and many other psychologists, it is difficult, if not impossible, to distinguish these conditions [governing the use of the word explanation] from the ones governing the use of the word description. This apparent equivalence suggests that, in practice, explanation is description" (p. 449). Baum was presumably making a valid and important point about Mach's view of explanation as a description of the sensory experience of the behaving scientist, and Skinner's acknowledgment of Mach's influence on him (see also Smith, 1986, 1995; Zuriff, 1985, p. 265). To be sure, Skinner's own writings contribute to a sense of confusion about a distinction between description and explanation. For example, chapter 2 of The Behavior of Organisms (Skin- In opposition to the deductive model of explaner, 1938) opens as follows: "So far as nation is the radical positivistic position, at times
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enunciated by Skinner (1950), that theories are unnecessary. The scientist's task is to manipulate experimentally events that are directly observable in order to discover the facts as they are, and nothing more.... Skinner's atheoretical position has generated much confusion simply because it is itself unclear. It is one thing to state that at a particular time in the history of psychology the systematic collection of data without any theoretical preconceptions, but with a desire to control phenomena, may be more productive than self-conscious efforts to erect theoretical structures that cannot be supported by available empirical evidence. It is quite another thing to state that theories are unnecessary and should be ignored as a scientific goal. Skinner seems to maintain both these positions, frequently arguing in favor of the latter, but defending it in terms of the former. (pp. 20-21)
Implicit in the statement above is that in order for a statement to be considered as genuinely explanatory, it must (a) appeal to more than a directly observable event (i.e., publicly observable), (b) predict outcomes in unencountered cases, and (c) be theoretical. In point of fact, such comments as those of Kendler and Spence (1971) are well wide of the mark. First, as has already been discussed, behavior analysis incorporates factors that are not publicly observable through its position on private events. Second, behavior analysis is intensely concerned with prediction. This concern follows directly from its focal concern with causal explanation. For example, Skinner speaks extensively of the importance of causal explanation of behavior in chapter 3 of Science and Human Behavior (1953): The terms "cause" and "effect" are no longer widely used in science. They have been associated with so many theories of the structure and operation of the universe that they mean more than scientists want to say. A "cause" becomes "a change in an independent variable" and an "effect" a "change in a dependent variable." The old "cause-and-effect connection" becomes a "functional relation." The new terms do not suggest how a cause causes its effect; they merely assert that different events tend to occur in a certain order. This is important, but it is not crucial. There is no particular danger in using "cause" and "effect" in an informal discussion if we are always ready to substitute their more exact counterparts. We are concerned, then, with the causes of human behavior. We want to know why men be-
have as they do. Any condition or event which can be shown to have an effect upon behavior must be taken into account. By discovering and analyzing these causes we can predict behavior; to the extent we can manipulate them, we can control behavior. (p. 23)
The important theme of this passage is its practical concern with causality: effective action leading to manipulation and control. In related passages Skinner continued on the theme of practical, effective action by talking about the importance of prediction, beyond description. For example, in one case he (1953) stated that The scientific "system," like the laws, is designed to enable us to handle a subject matter more efficiently. What we call the scientific conception of a thing is not passive knowledge. Science is not concerned with contemplation. When we have discovered the laws which govern a part of the world about us, we are then ready to deal effectively with that part of the world. By predicting the occurrence of an event we are able to prepare for it. By arranging conditions in ways specified by the laws of a system, we not only predict, we control: we "cause" an event to occur or to assume certain characteristics. (p. 14)
In another case he (1961) stated, A science must achieve more than a description of behavior as an accomplished fact. It must predict future courses of action; it must be able to say that an organism will engage in behavior of a given sort at a given time. (pp. 70-71)
Thus, prediction is also central to the behavior-analytic position. Prediction is prized not because it confers a logical status to a statement, but rather because it mediates practical action. For example, if an individual can predict the future because one knows causeand-effect, functional relations, then that individual's life will presumably be better because one can prepare for impending events, either by (a) gaining something that would otherwise be missed or (b) avoiding something that would otherwise be encountered. The various explanations are to be offered at a level of generality that will promote these kinds of effective action in new circumstances. Third, behavior analysis has never
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tities must be described in different terms (Skinner, 1950). It further rejects the assumption that causal explanation in psychology, and psychological knowledge in general, consists in framing such theories. Indeed, behavior analysis argues that the assumption that psychological knowledge necessarily consists in the formulation of such theories and explanations is a further illustration of the same mentalistic The experimental psychologist is fundamentally problem. Thus, Skinner put it as folinterested in accounting for behavior, or explaining behavior, or in a very broad sense under- lows: rejected theories in principle. For example, Skinner (1938) stated that "The mere accumulation of uniformities is not a science at all. It is necessary to organize facts in such a way that a simple and convenient description can be given, and for this purpose a structure or system is required" (p. 45; see also Moore, 1975, pp. 130 ff.). In another passage, Skinner (1972) stated.
standing behavior.... Behavior can only be satisfactorily understood by going beyond the facts themselves. What is needed is a theory of behavior.... Theories are based upon facts; they are statements about organizations of facts.... But they have a generality which transcends particular facts and gives them a wider usefulness. Every science eventually reaches the stage of theory in this sense. Whether particular experimental psychologists like it or not, experimental psychology is properly and inevitably committed to the construction of a theory of behavior. A theory is essential to the scientific understanding of behavior as a subject matter. (pp. 301-302)
The important point is that behavior analysis regards theories and explanations as verbal behavior. They are important because they function as a form of discriminative stimulation that guides future action through either (a) direct manipulation of environmental events or (b) action when direct manipulation is not feasible, as in some cases of prediction and interpretation. What behavior analysis does reject is the traditional view of theories and explanations as formal statements that appeal to causal events and entities in other dimensions, with observational and theoretical terms, in which the latter are operationally defined as either intervening variables or hypothetical constructs (cf. Moore, 1996, 1998; Zuriff, 1985, chap. 4 and 5). In particular, behavior analysis rejects the sorts of mentalistic theories and explanations that appeal to unobserved events and entities that take place somewhere else, at some other level of observation, in a different dimension (neural, psychic, mental, subjective, conceptual, hypothetical), in which those events and en-
The theories to which objection is raised here are not the basic assumptions essential to any scientific activity or statements that are not yet facts, but rather explanations which appeal to events taking place somewhere else, at some other level of observation, described in different terms, and measured, if at all, in different dimensions. ... Theory is possible in another sense. Beyond the collection of uniform relationships lies the need for a formal representation of the data reduced to a minimal number of terms. A theoretical construction may yield greater generality than any assemblage of facts; such a construction will not refer to another dimensional system. (Catania & Hamad, 1988, p.
77)
Clearly, behavior analysis argues that it does offer an effective explanatory system for psychology and its critics fail to recognize this system.
BEHAVIOR ANALYSIS AND THE TWO FORMS OF TRADITIONAL EXPLANATIONS Instantiation Skinner's objections to the two forms of traditional explanations considered in the present article are quite forthright. Let us consider instantiation first. Objections here are to be found in his criticisms of Stevens and, to a lesser extent, Hull. Some are veiled: But the most elementary preliminary research shows that there are many relevant variables, and until their importance has been experimentally determined, an equation which allows for them will have so many arbitrary constants that a good fit will be a matter of course and cause for very little satisfaction. (Skinner, 1950, p.
216)
Others are less so, as in the following
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indictment of Stevens' explanatory All philosophers, of every school, imagine that causation is one of the fundamental axioms or practices: postulates of science, yet, oddly enough, in adThe operational attitude, in spite of its shortcomings, is a good thing in any science but especially in psychology because of the presence there of a vast vocabulary of ancient and nonscientific origin.... What happened instead was the operationism of Boring and Stevens. ... It was an attempt to acknowledge some of the more powerful claims of behaviorism (which could no longer be denied) but at the same time to preserve the old explanatory fictions unharmed.... A concession is made in accepting the claim that the data of psychology must be behavioral rather than mental if psychology is to be a member of the United Sciences, but the position taken is merely that of "methodological" behaviorism. According to this doctrine the world is divided into public and private events, and psychology, in order to meet the requirements of a science, must confine itself to the former. This was never good behaviorism, but it was an easy position to expound and defend and was often resorted to by the behaviorists themselves. It is least objectionable to the subjectivist because it permits him to retain "experience" for purposes of self-enjoyment and "non-physicalistic" self-knowledge.... The position is not genuinely operational because it shows an unwillingness to abandon fictions. ... What is lacking is the bold and exciting behavioristic hypothesis that what one observes and talks about is always the "real" or "physical" world (or at least the "one" world) and that "experience" is a derived construct to be understood only through an analysis of verbal (not, of course, merely vocal) processes. (Skinner, 1945, pp. 271, 292-293)
vanced sciences such as gravitational astronomy, the word "cause" never occurs. (Russell, 1932, p. 180)
One example might be the gas laws, in which various mathematical relations are expressed among pressure, volume, and temperature. Suppose we state that (P IX V)/T1 = (P2 X v2)/T2, where p1 is pressure on a given amount of gas at an initial time, v, is the volume of the gas at the initial time, T1 is the temperature of the gas at the initial time, P2 is pressure on the same amount of gas at a second time, v2 is the volume of the gas at the second time, and T2 is the temperature of the gas at the second time. On the view argued here, the gas laws are an example of the secondand third-stage scientific activity described by Skinner (1972, pp. 307 ff.). That is, to repeat Skinner's argument, during the first stage, investigators are concerned with identifying basic data. During the second stage, investigators are concerned with expressing orderly relations among data. During the third stage, investigators are concerned with deploying more general concepts as they develop explanations and make higher order "statements about statements" (Skinner, 1953, p. 14) and "statements about organizations of facts" (Skinner, 1972, p. 302). The activities build on one another, and weaknesses at lower levels cannot be corrected at higher levels. Cause-and-effect statements are relevant during the first stage. In the gas laws, we see that the product of pressure times volume will always be the same if the temperature and amount of the gas remain constant, and that the ratio of volume to temperature will always be the same if pressure and amount of the gas remain constant. At the heart of the gas laws is some operation performed from without that causes a change in the situation: pressure is increased or de-
Thus, Skinner objected to Stevens' explanatory practices, which Boring (1950, pp. 657-659) called "behavioristic" because of their commitment to a particular interpretation of operationism, on at least two grounds. First, it was not pragmatic, in the sense that it did not lend itself to the control of the behavior of the individual organism by occasioning the manipulation of factors in space and time to secure a given outcome. Second, it was mentalistic, in that it was concerned with validating appeals to causal events and entities in other dimensions. To be sure, Skinner was also influenced by Bertrand Russell, who among many important things stated that laws creased, volume of the container is inin many mature sciences were not es- creased or decreased, temperature is increased or decreased. Thus, we see that sentially causal in nature:
SCIENTIFIC EXPLANATION the gas laws formulate the appropriate relations among these data, and these relations are used to organize many observations concerning many different kinds of gases. As noted earlier, the process of going from first- to second- to third-stage statements provides the foundation for scientific laws and explanations, and the process is not wisely circumvented. Stevens' version of science sought to describe the form of the observed relations but to remain silent on the nature of a "mechanism" that had produced them. The question remained as to what cause-and-effect relations produced the data being described. Recall that Skinner pointed out that "it was Stevens ... who then continued to believe in the existence of mental life" (Catania & Hamad, 1988, p. 217), and "S. S. Stevens has applied Bridgman's principle to psychology, not to decide whether subjective events exist, but to determine the extent to which we can deal with them scientifically" (Skinner, 1969, p. 227). The implication of the operationism of Boring and Stevens is that mental processes are causing the behavior, but that psychology as a science cannot deal with the mental processes because they are not publicly observable; instead, psychology must confine itself to events that are accessible to at least two observers, such as by describing the mathematical relation between independent and dependent variables and nothing else. Although Stevens' approach to science may yield certain benefits, presumably those benefits do not follow from the reasons Stevens believed they did. Moreover, there are also liabilities to Stevens' approach, and from the behavior-analytic perspective those liabilities conspicuously outweigh any such benefits.
Behavior Analysis, Instantiation, and the Matching Law
Interestingly, Skinner never commented very much on a topic that has been prevalent in the literature of the experimental analysis of behavior since
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the early 1960s: the quantitative analysis of behavior and the matching law. For example, in some of this research, the distribution of choice responses is taken as a quantitative measure of response strength. When Skinner did comment, his comments were generally critical: "To return to choice after better measures of strength are available is like returning to the gas laws for information about the behavior of molecules after better ways of observing them have been discovered" (Skinner, 1986, p. 232). One possibility is that Skinner's general disdain for the matching law and associated quantitative research is related to the heavy influence of Stevens' mode of explanation on that research. Indeed, Stevens' strong influence on individuals in the Harvard department interested in the experimental analysis of behavior is quite ironic, given that much of the work was carried out by those who worked or studied in an intellectual tradition established by Skinner and given the mutual antipathy between Skinner and Stevens concerning philosophy of science. In that Skinner expressed so much fundamental concern with Stevens' mode of explanation, one wonders why Killeen (1976) suggests that there is "much about Stevens of which experimental analysts of behavior would approve" (p. 123). In any case, let us now critically examine how the matching law exemplifies instantiation and Stevens' approach, and note some objections to the whole enterprise. The matching law aims to mathematically describe a set of data: the relation between the ratio of response rates on concurrent schedules and the ratio of reinforcement rates obtained from those schedules. The specific relation, of course, is that the ratio of responding is proportional to the ratio of obtained reinforcement. Thus, in the fashion of Stevens' psychophysical law, the matching law equation is (b1/ b2) = k(rl/r2)n. The terms b, and b2 designate the behavior allocated to Alternatives 1 and 2 (actually, these terms can reflect either discrete responses or
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time spent responding), the term k is an individual difference parameter, the terms r, and r2 designate reinforcement obtained from Alternatives 1 and 2, and the superscript n designates the important term, the relation between responding and reinforcement. In the ideal case, n = 1, resulting in a ratio of responding that "matches" the ratio of reinforcement. In the influential article in which he proposed his formulation of the psychophysical law, Stevens (1957) wrote concerning the description of his data that When we convert this equation to logarithmic form we obtain a linear equation which has a certain practical usefulness, for the function can then be represented by a straight line in log-log coordinates. The slope of this line corresponds to the exponent n. (p. 162)
The logarithmic transformation has also been influential in the matching law research, in the sense that the equation expressing the relation between the ratios of behavior allocated to the alternatives and reinforcement obtained from the alternatives can likewise be transformed to logarithmic terms: log(b,/b2) = n log(r,/r2) + log k. Readers may recall that the logarithmic transformation of behavior and reinforcement ratios was anticipated by Staddon (1968), another graduate of the Harvard department, who had noted a simple power-law relation obtained between the ratios. In any case, in mathematical terms, k is the intercept, and n is the slope, of the line when the data are graphed logarithmically, just as with Stevens' psychophysical law. Readers may also recall that Baum (1979) has argued in favor of the generalized matching law, specifically citing Stevens (1957): In experiments with concurrent variable-interval schedules, when the ratio of responding or time spent at two alternatives ... is graphed in logarithmic coordinates as a function of the ratio of reinforcement ... obtained from the two alternatives, the data points usually conform to a straight line: ... Exponentiating both sides of this equation produces a power function of the type familiar in psychophysics (Stevens, 1957,
...). (p. 269)
It follows fairly clearly, then, that explanation in matching law research subscribes to explanation by instantiation, as exemplified in Stevens' work. Just as performance in psychophysical tasks is held to be "explained" when an equation is formulated with estimated parameters that describes the relation between the actual, "objective" physical magnitude of a stimulus and a subject's estimates of the "subjective" magnitude of that stimulus according to some scale, so is performance on concurrent schedules held to be "explained" when an equation can be formulated with estimated parameters that describes the relation between the distribution of responses and the distribution of obtained reinforcement. The problems with matching law analyses derived from Stevens' analyses are conspicuous. The matching law is often said to be a descriptive or tautological law involving an intervening variable of "value," rather than a causal law (Rachlin, 1971). In addition, its proponents often appeal to "scaling" of "subjective" reinforcement value as a means to validate it, as the following passages imply: The independent variables ... are measured on arbitrary physical scales, each of which may be transformed according to different function rules. These transformed physical scales may be thought of as "subjective scales." ... Such a formula suggests it is possible to predict choice behavior by a particular concatenation of subjective scales. As before, these scales are defined in terms of behavior, by transforming independent, physical measures of a stimulus. (Killeen, 1972, pp. 490-491)
Assuming that choice depends on the values of the alternatives, we would rescale the value of rate of reinforcement according to a power function with an exponent equal to a. (Baum, 1974b, p. 232)
The matching law is ostensibly concerned with objectively describing the observed relation between obtained reinforcers and responding. However, as cited above, closer examination reveals that the actual underlying concern is with value in some subjective dimension and whether it has been scaled correctly, for example, through some
SCIENTIFIC EXPLANATION "transformation." The talk of scaling the various events in a subjective dimension is pure mentalism, and just as with Stevens' research, the practices of those investigating the matching law have uncritically institutionalized the mentalism. Moreover, as with Stevens' psychophysical law, there is little concern with the provenance of the behavior, and whether an organism's experience with the environment contributes to its present form. Indeed, Logue, Rodriguez, Penia-Correal, and Mauro (1984) found that pigeons' choice responding between large delayed and small immediate reinforcers in a "selfcontrol" procedure was in fact sensitive to critical events in their life histories. If one is to take the whole approach to scientific explanation of instantiation as shown in Stevens' and matching law research, one is required to know critical events in the life history to predict the general form of the birds' behavior. This requirement seems at variance with the often-asserted practical advantages of the approach. One can point out that one presumably does not need to know critical events in the life history or the "sensitivity" of the gas to know the relations among pressure, volume, and temperature. One can predict that the data from concurrent schedules will conform to some generalized equation or model, but this sort of predicting differs from predicting whether a subject will respond fast or slow, or on which operandum it will respond next. Indeed, the matching law describes a relation between responding and obtained reinforcement. If the reinforcers have already been obtained, then presumably one already knows how many responses have produced those reinforcers, and one doesn't need to predict anything. Moore (1983) pointed out a number of such ways that the matching law is suspect on such practical grounds. Indeed, Day (1969b) put the matter forcefully over 30 years ago:
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by the operationism of Boring and Stevens. (p. 326)
Caveat lector.
Deductions from Covering Laws What then about covering law explanations? Skinner's objections to covering law explanations may be found in his objections to hypotheticodeductive practices more generally (e.g., Catania & Hamad, 1988, pp. 77149). One objection focuses on how the behaving scientist is presumed to become knowledgeable about the subject matter in question. More specifically, hypothetico-deductive explanatory practices are based on a mentalistic epistemology and misrepresent the processes involved in researchers' becoming knowledgeable. Knowledge presumably involves a discriminative repertoire, and is to be analyzed in terms of stimulus control, contingencies, and so on, rather than in terms of a supposedly disembodied system of logic. A second objection is that hypothetico-deductive techniques lead to the continued use of practices that should be abandoned because they are wasteful. For example, the purported primacy of logical structure in covering law explanations means that researchers can make up a law, assert the law is true even though there is no independent basis for the assertion, and then, by using different tenses in the conclusion, make all sorts of claims about the validity of their insights into nature's mysteries. Researchers who use the past tense in the conclusion can claim to have explained the event. Researchers who use the future tense in the conclusion can claim to have predicted the event all along. In either case, all the researchers have really done is postdict the event. The situation is not changed if the law is called a theory or hypothesis, and the whole enterprise is justified as "hypothesis Strange blends of Skinner and conventional be- testing." Indeed, although taking the haviorism abound.... Mentalism among Skin- results of an experiment to prove that nerians is rampant, and they are quickly trapped one's hypothesis is true commits the
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logical fallacy of "affirming the consequent," many researchers nevertheless rely on this process to justify their research programs. This state of affairs is unfortunate because many resources can be wasted in pursuit of ideas of uncertain and idiosyncratic origin. A third objection, perhaps an extension of the second, is that the covering law explanations under consideration may themselves include mentalistic elements. Where does the covering law come from in the first place? It may come from folk psychology and include mentalistic elements. If so, these elements are incomplete and vague, they obscure important details, they allay curiosity by getting us to accept fictitious way stations as explanatory, they impede the search for relevant environmental variables, and they falsely assure us about the state of our knowledge. Thus, covering law explanations and hypothetico-deductive practices are inadequate because logic does not provide what it claims to provide. At the very least, the source of the covering law needs to be critically assessed (see discussion of the contexts of justification and discovery in Moore, 1998, pp. 235-237). Indeed, logic itself may be regarded as a behavioral phenomenon, rather than an extrabehavioral phenomenon that somehow dictates what is acceptable and what is not (Zuriff, 1985, p. 255). Presumably, this was Skinner's (1945) point when he stated that if "it turns out that our final view of verbal behavior invalidates our scientific structure from the point of view of logic and truth-value, then so much the worse for logic, which will also have been embraced by our analysis" (p. 277).
SUMMARY AND CONCLUSIONS In conclusion, the key to understanding behavior-analytic explanations is recognizing that they are verbal phenomena. Explanations may therefore be analyzed by critically assessing the contingencies that control their emission. The validity of an explana-
tion, for example, would be found in critically assessing the extent to which operations and contacts with data occasion its emission, relative to social and cultural traditions or other extraneous factors. This is what Skinner had in mind when he talked about "operational analysis" of verbal behavior involved in explanations or theories (e.g., Skinner, 1945). The behavior-analytic perspective on explanation is further based on pragmatism, which may be understood in terms of how an explanation contributes to enhancing practical knowledge (e.g., Zuriff, 1985, p. 257). However, as Moore (1998) has recently discussed, pragmatism should not be mistaken for instrumentalism, which is what many theorists often do, including those who believe themselves to be behavior analysts. Instrumentalism simply accepts the supposed utility of an explanatory statement without asking why it has proven useful; pragmatism seeks the reasons why. As Skinner has said over the years, We may quarrel with any analysis which appeals to ... an inner determiner of action, but the facts which have been represented with such devices cannot be ignored. (1953, p. 284) No entity or process which has any useful explanatory force is to be rejected on the ground that it is subjective or mental. The data which have made it important must, however, be studied and formulated in effective ways. (1964, p. 96)
It is often said that an analysis of behavior in terms of ontogenic contingencies "leaves something out of account," and this is true. It leaves out of account habits, ideas, cognitive processes, needs, drives, traits, and so on. But it does not neglect the facts upon which these concepts are based. It seeks a more effective formulation of the very contingencies to which those who use such concepts must eventually turn to explain their explanations. (Skinner in Catania & Harnad, 1988, p. 390)
Moreover, as Skinner (1974) put it, The truth of a statement of fact is limited by the sources of the behavior of the speaker, the control exerted by the current setting, the effects of similar settings in the past, the effects upon the listener leading to precision or to exaggeration or falsification, and so on. ... A scientific law
SCIENTIFIC EXPLANATION is derived from possibly many episodes of this sort, but it is similarly limited by the repertoires of the scientists involved. The verbal community of the scientist maintains special sanctions in an effort to guarantee validity and objectivity. (p. 140)
Clearly, the explanatory verbal behavior of scientists is complex, but it is nevertheless the product of factors that exist in space and time acting upon individuals who exist in space and time. The mental dimension does not exist in space and time for anyone, even in principle. The verbal behavior of the mentalist is influenced substantially by factors that are cherished for incidental and irrelevant reasons, and is therefore not a meaningful part of the explanatory process. As suggested earlier, behavior-analytic explanations codify uniformities, aid in the ordering of confusing data, and resolve puzzlement. They guide future action through (a) direct manipulation of environmental events, or (b) correlated action when direct manipulation is not feasible. The entire process is a naturalistic consequence of analyzing contingencies. It is not a process of (a) developing general forms of descriptive equations with estimated parameters; (b) testing hypotheses about the nature of supposed underlying mechanisms, even when those mechanisms are in the same dimension (and they usually are not); or (c) subsuming an event under a covering law when the sources of control over the covering law are not critically examined. Those practices lead to mentalism. The practical advantages of a naturalistic orientation for effective prediction, control, and explanation are manifold. REFERENCES Baum, W. M. (1974a). Definition in behavioral science: A review of B. B. Wolman's Dictionary of Behavioral Science. Journal of the Experimental Analysis of Behavior, 22, 445451. Baum, W. M. (1974b). On two types of deviation from the matching law: Bias and undermatching. Journal of the Experimental Analysis of Behavior, 22, 231-242. Baum, W. M. (1979). Matching, undermatch-
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