Kant and the Empiricists: Understanding Understanding

By Wayne Waxman

Oxford University 2005 Hardcover Buy here

Book Review
Reviewed by Robert Gressis

Philosophers used to tell the story that modern philosophy (i.e., philosophy in the seventeenth and eighteenth centuries) developed primarily as a set of answers to the fundamental questions, “how is it that I know anything?” and “what sorts of things am I justified in believing?” A modern philosopher’s answer to the first fundamental question constrained his answer to the second one. Thus, the rationalists, a group whose most prominent representatives include Descartes, Spinoza, Malebranche, and Leibniz, believed that we could get knowledge of the world both through our senses and reasoning on the basis of “innate ideas”—ideas essential to the mind of any rational being, which included such things as the ideas of substance, cause, and God. Consequently, the rationalists thought they were entitled to reason not just on the basis of sensory information, but also on the basis of innate ideas.  Thus, they concluded that there was a wide variety of things we could legitimately believe in, such as an immaterial soul, God, and necessary causal connections between things.

In contrast, the empiricists, who included Locke, Berkeley, and Hume, denied the existence of innate ideas, and thought that we could know things only through the senses. Instead of reasoning, like the rationalists, on the basis of innate ideas they thought we could assume only sensory information, and so produced very different kinds of arguments from the rationalists.

According to this story, which I’ll call “the traditional story,” modern philosophy culminated with the “Critical Philosophy” of Immanuel Kant (so-called because Kant’s main works were his three “Critiques”). Kant agreed with the empiricists that we could not achieve any knowledge of the world without sense data. But he agreed with the rationalists that concepts like causation, substance, and an immaterial soul (“fundamental concepts”) were not constructions out of sense data, like the empiricists held, but were rather contributions from a person’s mind. In short, were it not for the mind’s contributions to the world, we would not be able to organize sense data at all; but without sense data, there would be nothing for the mind to organize. As Kant famously put it in his Critique of Pure Reason, “Thoughts without content are empty, intuitions without concepts are blind.”

But the traditional story was abandoned some time ago. Twenty-five years ago, the philosopher Louis Loeb challenged the story in his From Descartes to Hume (Cornell University Press, 1981), only to receive the rejoinder from the scholar Martha Bolton that “it is wildly implausible to suggest that the [traditional story] stated significantly influences current research on the period” (The Philosophical Review, 1983, 89). Thus, even more than two decades ago the traditional story had few adherents.

What is so implausible about the traditional story? To start, it might not get modern philosophers’ main concern right. The traditional story has it that modern philosophers were most interested in how we come to have knowledge; but arguably they were more concerned about the best way to organize society or the source of our ethical obligations (as J. R. Schneewind has argued in his magisterial The Invention of Autonomy (Cambridge University Press, 1998)).

Second, it is not clear that modern philosophy can be characterized as centering on one main concern. Although many philosophers of the era occupied themselves mainly with epistemology (the study of knowledge), others focused on political philosophy, while still others primarily worked on theology. Some moderns produced work of lasting significance in all of these areas, and more.

Finally, what one sees as the salient issues of the era will determine how one groups philosophers. Loeb, for example, because he sees metaphysical issues as being of primary importance, characterizes Berkeley as a follower of the rationalist Nicolas Malebranche, instead of seeing him as a typical British empiricist.

That is part of the reason why Wayne Waxman’s massive new work, Kant and the Empiricists, stands out. Waxman defends a version of the traditional story, albeit with two significant changes. First, rather than dividing the moderns up into rationalists and empiricists, Waxman groups them into intellectualists (Descartes, Spinoza, Malebranche, and Leibniz) and sensibilists (Locke, Berkeley, and Hume). Second, instead of seeing Kant as the culmination and merger of the best of both the rationalists and the empiricists, Waxman casts Kant as a sensibilist, one who advanced on his sensibilist predecessor Hume (just as Hume did with Berkeley, and Berkeley did with Locke). As Waxman says, “My purpose in this book is to expound the transcendental philosophy of Immanuel Kant as a continuation of British Empiricism by nonempiricist means” (Waxman, 3).

Waxman sees Kant’s philosophical project as one that irons out the errors in Hume’s; yet while Hume is an empiricist, Kant is not. So what do they have in common such that Kant should be seen as a continuation of Hume? Waxman’s answer is that both Kant and Hume are sensibilists. This is why Waxman chooses to group modern philosophers as intellectualists or sensibilists rather than as rationalists or empiricists. If he divided the moderns between rationalists and empiricists, he would be unable to construe Kant as the successor to Hume. However because, in Waxman’s opinion, there are such strong similarities between Kant and Hume (and to a lesser degree, between Kant and Locke and Berkeley), he thinks it is important to classify Kant and the empiricists in such a way as to emphasize those similarities.

In order to grasp sensibilism, one has to first understand the view to which it is opposed: intellectualism. Intellectualism is the thesis that fundamental concepts are ideas innate to any rational mind. According to the intellectualist, these innate ideas are present in the mind before a person has any experiences, and indeed make it possible for  the person is capable of comprehending his experiences in the first place. Without the innate idea of substance, for example, we would not be able to see the world as containing a vast number of separate objects; instead, we would see a mass of various and shifting colors.

Similarly, without the innate idea of cause, we would not be able to experience the world as consisting of objects related to each other in an understandable way. At best, substances would come and go, seemingly for no rhyme or reason. As Waxman helpfully puts it, without innate ideas, “we would be as much at a loss to discern [form] in what we see or touch as intelligent creatures familiar with portraiture would be to discern the face depicted in one of our portraits if they lacked any idea of human faces, or faces generally” (Waxman, 381).

Intellectualists endorsed the doctrine of innate ideas because they thought there was no other way to explain how people could experience reality in the way they do, namely, as consisting of discrete objects in a spatio-temporal causal nexus. Sensibilists disagreed. They hewed to sensibilism, the thesis that “all our ideas—perceptions, in Hume’s terminology, representations in Kant’s—originate in (are coeval with) being perceived, and have no existence prior to or independently of their immediate presence to consciousness in perception” (Waxman, 3).

In other words, sensibilists denied the doctrine of innate ideas, insisting instead that all of our ideas (thoughts, experiences, etc.) are acquired, either through our “outer senses” (vision, touch, hearing, smell, and taste) or our “inner sense” (our ability to reflect, not only on the data with which our outer senses present us, but also on the operations of our own minds). Given their rejection of innate ideas, sensibilists had to show how we came into possession of fundamental concepts. Their only options—or so the empiricists among them thought—were to trace such concepts either to a simple idea acquired through inner or outer sense, or to a complex idea constructed out of a number of simple ideas of inner or outer sense. Otherwise, if someone could find a fundamental concept that could not be constructed from the materials of inner and outer sense, then the sensibilists’ project would be defeated, and the intellectualists’ doctrine of innate ideas would carry the day.

For sensibilists, then, the question of origins was paramount: in order for a concept to be admissible for use, it had to be traceable to sensations or “perceptions of the mind’s own doings” (Waxman, 379). Sensibilists’ rejection of innate ideas not only gave rise to a period of immense philosophical creativity (where sensibilist philosophers came up with increasingly clever accounts of the genesis of fundamental concepts from sensations and reflections), but also to gradually more skeptical approaches to metaphysics.

For intellectualists, the fact that an idea was innate, and so in no way dependent on having sensations or reflections, allowed them to use innate ideas to speculate about all sorts of extra-sensory objects, such as an immaterial soul, God, and the afterlife. Sensibilists, by contrast, had to curtail their metaphysical explorations. Because all concepts were constructions out of sense data (either inner or outer), they could not be employed to describe things beyond the boundaries of sense.

However, not every sensibilist followed this rule. Locke, for instance, thought there had to be some ineffable “substrate” of material objects that partly explained why we experience the world the way we do, and that we could have a conception of this substrate, even if we could not be sure that our conception was accurate (Waxman takes this up in chapter 7). Berkeley was considerably more careful about his employment of concepts, but ran into problems in explaining how it was that God could have knowledge of the world, despite having no outer senses (Waxman investigates this difficulty in chapter 12).

Hume was the philosopher among the empiricist sensibilists who most carefully limited his application of concepts only to the sensory world. The metaphysical consequences of Hume’s strict adherence to sensibilism led to a far-reaching and severe skepticism. He claimed the concept of causal necessity (e.g., the fact that fire necessarily causes smoke given certain environmental conditions), or the fact that gravity necessarily causes objects to be attracted to one another) rests not on any apprehension of properties of objects, or of observation of one’s own ability to cause things to happen, but rather on one’s feeling of expectation. Very roughly, the story is this: if you see an event of a particular kind (say, someone’s jumping up into the air) precede another event of a particular kind (say, that person’s falling back down), then, after some time, you so strongly expect that someone’s jumping into the air to be followed by his falling back down that you would find his not falling back down hard to process. The feeling becomes so vivid that you conclude that the first kind of event causes the second kind.

There is much more to be said about Hume’s theory of causation than this, but Hume’s overall approach results in two difficulties. First, Hume’s employment of sensibilism issues in an almost-solipsistic metaphysics; in Hume’s view, the only thing a person can end up having warrant in believing in are his own perceptions.

Second, Hume runs into a difficulty with personal identity: although he adequately explains how a person’s notion of himself as a simple substance that persists through time in fact can be constructed out of sense perceptions, he winds up with no explanation of why it is that a person’s sensations seem all to be in the same “place,” as it were; that is, the fact that people experience a succession of ideas (perceptions, thoughts, etc.) instead of, for example, a bundle of thoughts all at once, is something that Hume could not explain, but which he thought needed explanation.

At this point, we are now positioned to see how Kant picks up Hume’s sensibilist mantle while abandoning Hume’s (and Locke’s, and Berkeley’s) empiricism. What makes Hume, Locke, and Berkeley empiricists is their belief that the only source of information about the world comes from our inner and outer senses. Kant remained a sensibilist by agreeing with Hume, Locke, and Berkeley that all concepts had to be constructed out of sense data, but he disagreed with them in limiting the source of sense data to data that comes from the use of the inner or outer senses. In addition to inner and outer sense, Kant posited a third source of information about the world: the “pure intuitions” of space and time.

It is Kant’s positing of the pure intuitions of space and time that separates his Critical Philosophy from the empiricism of Locke, Berkeley, and Hume, but it is his rejection of innate ideas that makes him a sensibilist. Thus, Kant’s philosophy is not a combination of empiricism and rationalism, but simply a version of sensibilism, one that lacks the empirical component so often tied to it.

According to Kant, space and time are neither objectively real intuition, nor are they constructed out of the data of inner and outer sense. Instead, space and time are phenomena resulting from the operations of the human mind, phenomena that allow us to experience the data of inner and outer sense. Moreover, Kant argues (in a manner too complex to be summarized in this review) that the phenomenon of time involves a sense of self, the kind of self that Hume felt he needed to posit, but could not figure out how to construct from sense data. Waxman shows both the problem Hume gets into with personal identity and Kant’s solution to it in chapter 3, although he promises greater elaboration in Time Out of Mind, the sequel to the volume under review.

Showing the existence of a sensibilist thread connecting the work of Locke, Berkeley, Hume, and Kant is Waxman’s master project in Kant and the Empiricists. Volume 1, Understanding Understanding, contains in-depth treatments of Locke, Berkeley, and Hume’s explanations of all our concepts in terms of the data of inner and outer sense. Volume 2, Time Out of Mind (which is not yet published), promises Waxman’s account of Kant’s theory of the self, as well as Kant’s derivations of all our concepts from the data of inner sense, outer sense, and the pure intuitions of space and time. Consequently, readers looking for detailed exposition of Kant’s philosophy of the material world will not find what they are looking for in Understanding Understanding.

However, Waxman’s extended treatments of Locke, Berkeley, and Hume are both provocative and illuminating. Waxman departs from standard readings of Locke, Berkeley, and (especially) Hume at almost every turn, but he provides an enormous amount of textual evidence for his interpretations. His prose, however, is quite dense (and unfortunately riddled with typographical errors); moreover, the book is not for the philosophically uninformed—it is a quite demanding read. But for those who are familiar with Locke, Berkeley, or Hume, Kant and the Empiricists is extremely rewarding; the detail of Waxman’s expositions of his subjects’ views is breathtaking, and he reveals their arguments to be more powerful than many of us contemporary philosophers would have suspected.

Finally, it should be noted that Waxman is unapologetically antiquarian in his approach to the history of philosophy. Unlike many contemporary historians of philosophy, Waxman does not try to extricate from the great philosophers of the past only those views or arguments of theirs that resonate with our contemporary intuitions. Instead, he tries to understand “the texts of early modern philosophers primarily in terms of their own projects” (Waxman, 16-17). Instead of catering to our current (and perhaps short-lived) intuitions, Waxman has tried to accurately represent the views of past philosophers, and he has produced a work that is challenging and illuminating as a result.