A Companion to Rationalism
Alan Nelson is Professor of Philosophy at the University of California, Irvine. He is a leading scholar of the great philosophical systems of the seventeenth and eighteenth centuries and has published widely on rationalism in the history of philosophy and in the philosophy of science.
A Companion to Rationalism
The Rationalist Impulse
Philosophers are rightly suspicious of the usefulness of broadly conceived labels and "-isms." They are particularly suspicious when the labels mark dichotomies. Rationalism thus qualifies as suspicious if it is taken to be a neatly delineated set of doctrines. The task assumed by this chapter is not to find such a set, but instead to provide an analysis of what I shall call the impulse to philosophize rationalistically. The analysis therefore does not purport to sharply distinguish a set of maxims or propositions characteristic of rationalism from another set proper to its foil, empiricism. Nor does it attempt to delineate specific doctrines to which all "rationalists" adhere. I shall, however, argue that attention to some overarching themes in rationalist systems of philosophy can be of considerable use in understanding the philosophical accomplishments of the great rationalists. Insufficient attention to these themes has often led to interpretations of rationalists that skew the dialectic with their empiricist antagonists in favor of the latter.
I shall draw some examples from Plato, who provides most of the earliest texts clearly articulating rationalist themes. The primary focus will be on the great thinkers from the seventeenth-century heyday of rationalism, but in conclusion some observations will be made about the rationalist impulse in Russell's logical atomism. This should help bring into relief some respects in which the triumph of empiricist sensibilities among historians of philosophy in the twentieth century and beyond has made the rationalist impulse rather alien. Naturally, this is not conducive to recovering the spirit of rationalist projects.
The primary and customary sense of the term "rationalism" characterizes a philosophical attitude toward knowledge. Knowledge itself is partly characterized both by the subjects, or possessors, of knowledge and by the objects of knowledge, the things to be known. Rationalism, therefore, bears on ontology since it requires an understanding of the natures of these subjects and objects. There are also characteristically rational processes or techniques for obtaining or developing knowledge, so rationalism bears on method, philosophical education, and the nature of philosophy itself.
The traditional series of contrasts with its foil, empiricism, thus begins with subjects and objects of knowledge. Traditional rationalisms identify the intellect, the mind, or the rational part of the soul (or even the State) as of primary importance in receiving and holding knowledge. The corresponding objects of knowledge are then non-sensory, general, and unchanging or eternal. Traditional empiricisms, by contrast, identify the senses, or common sense, or the sensitive part of the soul as of primary importance. The corresponding objects of knowledge are then the inhabitants of the temporal world in flux. Of course, rationalists have a story to tell about how some kinds of derivative knowledge depend directly on the senses. We can come to know that the senses are reliable indicators of what is beneficial to us and we can then know (as opposed to taking it for granted) that, for example, bread nourishes. Furthermore, absolutely all knowledge depends in some attenuated ways on the sensory because we need to learn more esoteric truths by first hearing or reading things that bring us to understand them. Empiricists similarly have a story to tell about the role of the non-sensory. The clearest example is Locke's essential reliance on innate operations of the mind. This is an extreme case, but all empiricists need to have some account of how abstract, general truths are derived from what is given by the senses.
These points are crucial to appreciating the depth of the chasm between rationalism and empiricism despite the pockets of shared concerns and overlap. It i