Copyright © 1999 Massachusetts Institute of Technology
"Rationalism" and "empiricism" are best understood as names for two broad trends in philosophy rather than labels for specific articulated theories. "Sensationalism," "experientialism," and "empirical theory" are among other terms that have been used to denote the latter doctrine, while "intuitionalism," "intellectualism," and "transcendentalism" have had currency in alluding to the former. In the traditional pantheon of philosophers, the classic rationalists are René DESCARTES, Gottfried Wilhelm Leibniz, and Baruch Spinoza; the classic empiricists are John Locke, George Berkeley, and David HUME. Immanuel Kant's transcendental theses, although removed from empiricism, do not fit readily into the rationalist picture either. Theorists are usually said to be "rationalists" or "empiricists" in light of a discerned family resemblance between one of their positions and a position championed by members of one of the traditional schools (cf. KANT).
Roughly put, empiricism is the view that all knowledge of fact comes from experience. At birth the mind is a tabula rasa. Our senses not only provide the evidence available to justify beliefs, they are the initial source of the concepts constituting these thoughts. Innate biases and dispositions may influence the ideas experience leads us to acquire, but we do not come into the world equipped with anything deserving the title of an "idea." Some ideas, the simple ones, are found directly in experience; others are derived from these by abstraction, analogy, and definition.
According to the empiricists, there are also no a priori truths, except for those analytic statements (for example, "All bachelors are unmarried," or "Triangles have three sides"), which, being matters of meaning, can be depicted in terms of definitional, hence necessary, relations among ideas. The seemingly special status of mathematics might then be explained on the assumption that mathematical statements are analytic. Some prominent empiricists, notably John Stuart Mill (1956), argued even mathematics was empirically derived.
Knowledge of all matters of fact, however, rests on inductively gained experience. In particular, scientific knowledge is not based on a priori or necessary principles. Reason does not supply the ultimate foundation for science, nor can it enable us to achieve certainty in these areas. Reason can help to organize and see the implications of what sense offers, and logic puts constraints on appropriate patterns of reasoning, but reason on its own cannot provide the wherewithal for understanding nature.
Rationalism may be given an equally rough description in terms of its denial of these central empiricist tenets. For the rationalist, experience is not the source of all knowledge. Some concepts are neither derived nor derivable from sense experience. The mind comes equipped with a set of innate ideas. What's more, reason or intuition, when properly tapped, can provide true beliefs or principles, albeit not all or even most of those we entertain; determining the truth of mundane claims about the height of a tree or if the milk has gone bad require sense experience. Inductive exploration will also play a role in discovering empirical regularities theoretical science incorporates and seeks to explain.
Reason has a higher calling. It furnishes a priori principles that are not only true, but are necessary, and are recognizably so. These principles are not stipulative definitional truths; rather they delineate the real essences of the ideas of "God," "being," "triangle," and so on that they contain. In this way, they supply a bedrock of certainty upon which knowledge is built, and coherence with them is the sine qua non of acceptable hypotheses.
It is possible, then, to conceive of scientific theories along the lines of axiom systems in mathematics. The first principles (or axioms) of these systems of science are not established by the inductive amassing of evidence. They are intuited by reason as true and necessary. These principles provide the foundational certainty from which the rest of science can be seen to follow deductively.
The rationalist/empiricist distinction, as drawn above, is to be distinguished from the contrast between mentalistic versus behavioristic approaches to psychology and mind. Empiricists as well as rationalists were mentalists, and both placed heavy emphasis on the role of consciousness in cognition. None of these thinkers had qualms appealing to mental states, and none were committed to the view that human behavior was not mediated by and dependent upon such internal states. Descartes (Discourse on the Method, part 5, from Descartes 1984-85) perhaps stands out in his clear refusal to attribute CONSCIOUSNESS to animals and in his conviction that their behavior can be fully explained mechanistically without appeal to mental intermediaries. Hume, in his Treatise of Human Nature (1960: book I, sect. 16), forcefully argues that animals are endowed with thought and reason. Everyone agreed, however, that the coin of the mental was ideas, and the empiricists' ideas were no less representational than those of the rationalists (cf. BEHAVIORISM and MENTAL REPRESENTATION).
Empiricists did stress and give wider scope to the role associative processes were seen to play in the acquisition and manipulation of ideas, and experienced similarity had a more prominent place in their theories. But it is a mistake to think they allowed for no other kinds of mental transitions and processing. In fact, Locke spends a chapter of his Essay Concerning Human Understanding (1975: book II, ch. 33) warning how too ready reliance on the happenstance of experiential co-occurrences will result in false beliefs.
At the same time, there is no reason to assume rationalists did not allow many transitions of thought and imagination were fueled by past associations or presently sensed similarities. For example, Descartes' influential theory of the emotions (Passions of the Soul, from Descartes 1984-85), has elements that are not only sensationalist but are behaviorist and associationist. It is also true, especially in his theory of vision (Dioptrics, from Descartes 1984-85), that Descartes talks of more intellectual-like reasoning and calculating that is neither conscious nor involves conscious ideas. But these processing claims are in tension with the standard interpretation of Descartes as the foremost champion of the view that all mental states are conscious.
Although the rationalist/empiricist dichotomy, loosely characterized, does have its uses in limited contexts, care must be taken employing it to make specific claims about specific historical figures. Further caution is warranted when their work is cited or used to support contemporary doctrines. For example, many seventeenth- and eighteenth-century arguments for innateness hinge on the claim that ideas such as "God" or "triangle" could not be acquired, because no actual instances of these sorts of concepts could possibly be found in experience. Current-day proponents of innate ideas, stressing inductive indeterminacy, extend the claim to ideas for which there clearly are observed cases. Similarly, rationalists often argued apprehension of certain principles, like the principles of noncontradiction and identity, must be a priori, because they are a prerequisite for having any thought at all. Current proponents of the INNATENESS OF LANGUAGE, for example, tend not to make comparable claims about the principles of universal grammar (cf. NATIVISM; NATIVISM, HISTORY OF; POVERTY OF THE STIMULUS ARGUMENTS).
The classic writers forged their theories in and against a background of assumptions about physics, mind, physiology, religion, and science in general that have been largely abandoned. Moreover, in the course of time, concepts and doctrines of consciousness, learning, innateness, mental states and processes versus nonmental states and processes, biological inheritance, and the like have come to be understood along new dimensions. This has led to further blurring the meaning and significance of the distinction between rationalist and empiricist positions.
In contemporary psychological literature, for instance, Hermann von HELMHOLTZ is frequently cited as the founding father of the cognitivist approach to perception. Since Helmholtz's (1950) unconscious inference model postulates mental representations and processes, his theory is said to stand in opposition to Gestalt, behaviorist, and Gibsonian positions. Yet Helmholtz's model is strikingly similar to the one Berkeley offers in his New Theory of Vision (from Berkeley 1948-57), and it explicitly mirrors Mill's account of inductive inference. But whereas the staunch empiricist Mill (1973) allows that certain visual inferences may be instinctive, Helmholtz claims (1950) his main result has been to show how a range of phenomena, usually thought innate, can be explained in terms of learning and psychological processing. So, for example, on the important issue of the fusion of binocular images, Helmholtz offers a cognitive account, in opposition to the purely physiological, nativist explanation given by Descartes and other theorists (cf. GIBSON; GESTALT PERCEPTION; see also PARSIMONY AND SIMPLICITY).
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Copyright © 1999 Massachusetts Institute of Technology