In a wonderful book “Explaining Social Behavior”, the author, Jon Elster, writes on reductionism and analogies in inter-disciplinary thinking.

“The various scientific disciplines may stand in one of two relations to one another: reduction or analogy. Reduction takes the form of explaining phenomena at one level in the hierarchy of sciences in terms of lower-level phenomena (see Figure).

Reductionist programs tend to be controversial. For a long time, many biologists vehemently claimed that the reduction of biology to chemistry could not possibly work - but it did. From Emile Durkheim onward many have argued that social science cannot possibly be reduced to psychology. A central claim in the present work is that it can.

Figure

Between these two reductions there is the reduction of psychology to biology. The relevant biological disciplines are genetics, physiology, developmental biology, and evolutionary biology. The first two study proximate causes of the structure and behavior of organisms, the last two remote causes in the history of the individual organism or of the species. The study of structure and the study of behavior are related, in that structure provides both opportunities for behavior and constraints on behavior. The fact that we have two kidneys and only need one allows us to donate one to a sibling for transplantation and makes it possible for social norms mandating or banning that practice to arise. Yet the reason we have two kidneys is not to allow transplantations from living donors. Many structures exist because of what they allow us to do, but this is not an example. Often, however, it is hard to tell whether the enabling effects of a structure are accidental or explanatory.

The relevance of biology for the social sciences ought to be obvious, since their domains overlap. Yet many social scientists resist biological explanations on the ground that they are "reductionist." This is a strange accusation for those who believe, as I do, that reductionism is the engine of progress in science. Yet if "reductionism" is prefixed by "premature," "crude," or "speculative," the objection can be well founded.

Premature reductionism is observed when scholars who are convinced of the ultimate feasibility of moving from higher-level to lower-level explanations try to do so before the requisite measurement techniques, concepts, and theories are in place. A classical example is Descartes's mechanistic physiology, on which Pascal commented in the following terms: "Descartes. We must say summarily: 'This is made by figure and motion,' for it is true. But to say what these are, and to compose the machine, is ridiculous. For it is useless, uncertain, and painful." Today, those who propose algorithms for pattern recognition and automatic translation may be in a similar situation. The tasks of recognizing a human face and of detecting nonsensical sentences that we perform effortlessly are, so far, beyond the capacity of artificial systems.

Crude reductionism is observed when scholars try to explain specific behavior in biological terms rather than explaining the capacity or tendency, which in a given case mayor may not be used or realized, for such behavior. Trying to explain political behavior in terms of the "territorial imperative" found in lower animals is an example. Another is the idea that the practice of weightlifting can be explained as the outcome of sexual selection, analogous to the feathers of the peacock or giant antlers in deer. Many other cases could be cited.

Speculative reductionism is observed when scholars produce "just-so" stories that provide an account of how given behavior could have emerged, without showing that it did emerge in that way. Sociobiology and the closely related field of evolutionary psychology abound with examples, as when scholars argue that self-deception has evolved because of its evolutionary benefits or that postpartum depression in women has evolved as a bargaining tool.

To say that bad reductionism is bad is not very illuminating. The desire to reduce complex phenomena to simpler may take simplistic forms, but so can any research strategy in science. Overwhelmingly, the history of science shows that reductionism is a progressive and antireductionism an obstructionist force in science. History also shows the risk of using analogies between one scientific discipline and another to generate hypotheses. In itself, the use of analogies is harmless: scientific hypotheses are to be judged by their descendants (testable implications), not by their ancestors. Yet when analogical thinking leads scholars to privilege one kind of hypothesis over others, the result often ends up in the cabinet of horrors of scientific thought. The analogy with society and biological organisms, for instance, has been used to support the idea that societies, like organisms, are self-regulating entities with built-in homeostatic correction mechanisms (e.g., revolutions). In the nineteenth century, scholars debated what, in society, would correspond to the cell in the organism, without asking themselves whether there was any reason to expect any analogy at all. Other writers have used physical rather than organic analogies and looked for the social equivalent of Newton's laws or the force of gravity. Scholars who argue that the social sciences can have an impact on the object they study routinely invoke Heisenberg's uncertainty principle, as if the profundity of his principle could turn their truism into something equally profound.

I consider some findings from physiology and brain science that hold out the promise of offering reductionist accounts of phenomena such as fear, trust, and "jumping to conclusions." I discuss the theory of natural selection, which has been put to the double use of reduction and analogy. I argue that while some reductionist attempts are plausible, others are premature, crude, or speculative. The use of natural selection as an analogy for social phenomena has a more dubious value. One reason why, I set out the mechanisms of natural selection in a manner that may seem excessively detailed in a book about social science (yet much too superficial to serve as an exposition of the subject) is to show that nothing remotely comparable exists in the social world. Hand waving by social scientists about "social selection" and "social evolution" is too lacking in precision and focus to be taken seriously.”