Of Planets and Cognitions: The Use of Deductive Inference in the Natural Sciences and Psy c h o l o g y Inferences of unobserved cognitive events in psychology are not the same as the inference of the recently discovered, but unobserved extrasolar planets in astronomy. Unlike astronomy, or the other natural sciences, psychology has no experimental foundation of laws that justify such inferences. H E N RY D. SCHLINGER JR. agazines such as the SKE P T I C A L INQU I R E R en c o u r - age skepticism of beliefs and claims, ranging from Mthe extraordi n a r y to the quotidian, that often char- ac t e r i z e the so-called pseudosciences. Unscientific claims also occur frequently within established disciplines such as the social sciences, in which it is fairly easy to engage in biased judgment and illogical thinking. To understand the ease with which belief can transcend science, one need only examine such false claims as facilitated communication and rep re s s e d me m o r y syndrome, not to mention more entrenched beliefs such as psychoanalytic personality theory. Even the natural sciences are not immune to this problem, because humans are fallible and their judgments can often be clouded by personal beliefs, even in the face of contrary scientific evidence. What distinguishes the natural from the social sciences, SKEPTICAL INQUIRER September/October 1998 1 however, is that in the natural sciences there is a self-corrective cally proven laws and principles. Beginning with Galileo and mechanism inherent in the scientific methodology. Newton, scientists have made direct observations of visible Because the social sciences lack such a mechanism, scientif- bodies and the forces they exert on one another. After con- ically questionable claims and beliefs have a much longer life ducting experiments on the motion of objects on earth, scien- than those in the natural sciences. tists were able to extrapolate the discovered laws to celestial As one who believes that psychology can and should be a bodies. For example, as David Palmer at Smith College points natural science of behavior, I am uneasy with the fact that out, Isaac Newton explained the effects of the moon’s gravita- much of modern psychology is based upon unobservable men- tional pull on ocean tides using his laws of motion even tal events. Some psychologists may insist that inferring such though he obviously never carried out direct experiments on events is an unavoidable pitfall of a discipline in which the area ocean tides. Nevertheless, we accept his interpretation as a of study has historically been the mind. Others may argue that plausible explanation based on the strength of the laws of psychology simply emulates the natural sciences, where infer- physics he discovered under more controlled conditions. ences are regularly made about unobservable events. A recent The experimental findings of Galileo and Newton have example in astronomy provides an opportunity to compare been formalized as the laws of motion and the theory of grav- inferences in psychology with those in the natural sciences. ity which explains them. With these laws as a scientific foun- In October 1995, astronomers at the Geneva Observatory dation, the discoverers of the extrasolar planets were justified in Switzerland announced with much scientific and media fan- in deducing, and inferring, the existence of the planets based fare the discovery of the first planet outside our own solar sys- on observations other than those of the planets themselves; tem. The planet is in a tight orbit around 51 Pegasi, a star in namely, slight inconsistencies in the pulsations of the stars the constellation Pegasus. Just three months later, astronomers around which the planets orbit. According to David Black, at San Francisco State University and the University of director of the Lunar and Planetary Institute in Houston, sci- California at Berkeley announced the discovery of two other entists scrutinize a star for signs that it is affected by the grav- extrasolar planets orbiting the stars 70 Virginis, located in the itational tug of an orbiting planet. As the planet moves from constellation Virgo, and 47 Ursa Majoris. The astronomers one side of the star to the other, its gravitational pull moves the speculated about the orbit and minimum mass of each planet, star back and forth. Astronomers are able to detect this effect but could offer no other details because the planets themselves as a slight wobble in the star’s overall movement across the sky. had not been directly observed. The practice of deductive inference is an integral part of the The initial response from the scientific community was natural sciences, such as molecular biology and astronomy, rightly one of skepticism—these were, after all, potentially especially when the objects of interest are undetectable by the momentous discoveries that re q u i red verification. Ot h e r naked eye. The use of, and thus the credibility of, deductive astronomers later replicated the initial observations and mea- inference in science depends on the prior discovery of repro- s u rements, although still without observing the planets ducible cause-and-effect relationships between variables in the directly. Although the 51 Pegasus report was strongly ques- subject matter. From this collection of facts, scientists induce tioned, researchers have now inferred by similar means the the laws or principles from which they can then deduce, or presence of at least eight planets outside the solar system. Of predict, the existence of phenomena that have not yet been or course, it is not possible for the astronomers to have observed cannot yet be subjected to experimental analysis. For example, the planets given the available technology, because the planets’ James Watson, Francis Crick, and their colleagues deduced suns are too bright to allow reflected light from the planets to what is arguably the greatest biological discovery of the twen- be seen. But if one of the axioms of scientific methodology is tieth century. They discovered a theoretical model of the likely objective observation, then it is not unreasonable to ask: How structure of the DNA molecule, based on the known laws of can scientists accept these claims without direct observation? chemistry and biology. (In late May 1998 NASA announced that the Hubble Most historical and contemporary psychological theories Space Telescope may have taken the first image of a planet out- are largely deductive in that they infer unobservable processes. side our solar system, an object 450 light-years away in Taurus These inferences about unobservable cognitive (from “cogni- designated TMR-1C. That is an exciting possible discovery, tion”: the act or process of knowing) processes are offered to but it doesn’t affect my general point. Most expected extraso- explain how individuals obtain knowledge about their world. lar planets will remain beyond Hubble’s optical reach.) The history of psychology is replete with inferred, unobserv- The answer is that the discoverers of these extrasolar plan- able phenomena, including the id, ego, and super-ego, the ets applied a form of deductive inference based on scientifi- mind, the self, personality, memory, and consciousness, among many others. In the most recent model of psychology—the Henry D. Schlinger Jr. is an associate professor of psychology at i n f o r m a t i o n - p rocessing model—cognitive processes are Western New England College in Springfield, Massachusetts, and likened to computer hardware and software functions and is the author of several experimental and theoretical articles as then treated as if they possessed the same properties. For exam- well as the author of A Behavior Analytic View of Child ple, memory is conceptualized as representations of experience De ve l o p m e n t and (with Alan Poling), In t roduction to (input) which are stored (processed) and then retrieved at the Scientific Psychology, both published by Plenum Press. appropriate time (output). 2 September/October 1998 SKEPTICAL INQUIRER In psychology, the inaccessible realm is inside the individual, and theorists deduce the existence of unobservable even t s — c o g n i t i o n s — solely from observable events—behavior. But we cannot conclude that this form of deductive i n f e rence is similar to that practiced by astronomers or is, in fact, valid at all, without s h owing that the deductive inferences are derived from scientific, lawful relationships between objective variables. Since most psy- chological theories do not have a solid scientific foundation, there remain substantive differ- ences between much of psychology and the natural sciences, like astron o m y . In psych o l o g y , cognitive events are not deduced from an experimentally established foundation of lawful relationships between objective eve n t s . Moreover, the inferred phenomena of astron- om y , (such as extrasolar planets), are potentially observable with improvements in technology, whereas cognitive structures and processes sim- ply are not. With very few possible exceptions (e.g., behavior analysis), there exists in psychology no systematic body of laws or principles, no basic units of analysis, and not even a com- monly accepted methodology for investigating behavior from which credible deductions about unobservable events could be made. If This Hubble Space Telescope photo of TMR-1C (lower left), issued in May, might be the first psychology is to advance as a science, then it image of a planet outside our solar system, but the other extrasolar planets reported so far must emulate the natural sciences in substance have been inferred from evidence based on physical principles. (S. Tereby and NASA) as well as form. Then, and only then, can deductive inferences be made about unobserv- language in the natural sciences has long since disappeared able events on the assumption that they possess some of the from the scientific vernacular, the ordinary nonscientific lan- same properties as events already verified through observation guage of psychologists and others regarding human behavior is and experimentation.