What Do 'Rationalism' and 'Empiricism' Mean?

W​HAT​ ​DO​ ‘R​ATIONALISM​’ ​AND​ ‘E​MPIRICISM​’ M​EAN​? By Justin Keena Many, if not most of the prominent early modern philosophers—that is to say, those philosophers from Descartes to Hume, most especially Spinoza, Locke, Leibniz, and Berkeley—are often classified in textbooks or other works on the history of philosophy as being either rationalists or empiricists. This classification, coupled with certain more or less vague remarks on the difference between Continental rationalism​ ​and British empiricism,1 ​may create the impression that the two movements, for lack of a better word, were clearly defined and independent ​schools ​of thought. However, any classification that finds a place for, e.g., the well-reasoned eccentricity of Spinoza (‘there is only one substance’) or the counter-intuitive conclusions of Berkeley (‘there is no matter;’ ‘the being of sensory things is their being perceived’) among a set of peers who supposedly held similar views would seem to be a rather questionable classification indeed. The confusion surrounding these terms (meaning here specifically, ‘rationalism’ and ‘empiricism’) is compounded by the fact that there is not a clearly stated and defined consensus among the various historians of philosophy as to their precise meanings; and some, in fact, make no mention of them as movements at all.2 ​As will be shown, there are, generally speaking, two ways in which these terms are used. The first way takes rationalism and empiricism in a rather broad sense, describing them more as ​trends ​or ​emphases ​in thought than as positions; whereas the other, in contrast, takes them in a stricter sense, defining them as particular, mutually exclusive epistemological ​positions.​ The first way characterizes the difference between rationalism and empiricism with broad strokes, but the second understands the two to be making distinct and opposing epistemological assertions. In this essay ‘rationalism’ always means ‘continental rationalism’ and ‘empiricism’ always means ‘British empiricism.’ ​Such works might mention specific rationalists or empiricists, and even name them as such, without discussing rationalism and empiricism themselves. 1 2 1 The difference between these two approaches results in a corresponding difference for their respective usefulness in attaining an understanding both of the individual philosophies involved and of early modern philosophy as a whole. The first approach, which takes the terms in a broad sense, though it does indeed indicate the general direction of the divergence between rationalism and empiricism, can without sufficient explication end up differentiating them in a way that is too vague, imprecise, and ambiguous. In other words, this approach tends to be as helpful as any generalization: it indicates the major issues involved, masks the particulars of the situation, and tends to oversimplify matters. Conversely, the more precise approach to these terms, while it does result in a more clearly defined understanding, is apt to create an incorrect impression of the more general tendencies of these movements of thought. And what is more, if rationalism and empiricism are defined as specific positions, other philosophers may have since (or previously) held an identical position; but they could not be called ​continental​ rationalists or ​British​ empiricists, since they may not belong to the place of these philosophers, and without question no longer belong to their time or intellectual climate. A certain measure of the broad approach, then, seems necessary to characterize this ​particular​ period in the history of philosophy and to contextualize the narrow approach, which is itself desirable for its precision. Now it should be kept in mind that the terms ‘rationalism’ and ‘empiricism’ themselves were only adopted later on: presumably, as an aid to explaining the development of past philosophy. As classifications, they must already be artificial in some measure; but the question remains, to what extent are they helpful as an aid to understanding early modern philosophy? In other words, in what way must they be defined in order to gain at least an adequate understanding of this era​?​ In order to offer an answer, we must first examine the two approaches that we have been characterizing. The etymology of the terms ‘rationalism’ and ‘empiricism’ indicates what is meant by these terms as used in the very broadest (and, we might add, least helpful) sense. That is to say, their respective 2 etymologies specify which means of knowing each term supposedly places its particular emphasis upon. ‘Rationalism’ is derived from the Latin ​ratio, ​which means, among other things, ‘mind’ or ‘reason.’ On the other hand, ‘empiricism’ is derived from the Greek ​ἐμπειρία (​empeiria​), meaning ‘experience.’ From this it is concluded that rationalists somehow emphasize reason over experience in its importance as a means of knowing, whereas empiricists emphasize experience over reason. Consider the following example of this particular ‘broad’ approach to rationalism and empiricism, the first of three that we shall mention here. “Empiricism,” one history of philosophy has it, “is the philosophy which restricts the method of philosophical research to experience and to the combination of the facts of experience, and the field of philosophy to the objects which can be known by this method.”3 “Rationalism,” on the other hand, “as understood by the [empiric] school, regards reason as the source of all knowledge; it is opposed to empiricism, which derives all knowledge from experience.”4 But what is meant by ‘reason,’ and what is meant by ‘experience’? Often philosophers, even the so-called rationalists, do not define precisely what they mean by ‘reason;’ and even when they do, such a definition would not necessarily be sufficient to distinguish the systems of the rationalists from (British) empiricism. For instance, Descartes offers the following definition in the first paragraph of the ​Discourse on Method: ​“the power of judging rightly and of distinguishing the true from the false.”5 But of course, given that definition, the empiricists would also agree that knowledge, even if it were all somehow originally derived from experience, must be confirmed by reason, that is, judged rightly. ‘Experience,’ too, is quite ambiguous. To illustrate this point, consider how the next two examples of this broadest approach to rationalism and empiricism both take Leo F. Miller, ​A History of Philosophy ​(New York: Joseph F. Wagner, Inc., 1927) 232. Ibid. 5 René Descartes, ​Discourse on Method and Meditations on First Philosophy, ​tr. Donald A Cress​ ​(Hackett Publishing Company: Indianapolis, 1993, 3​rd​ edition) 1. 3 4 3 ‘experience’ to mean ‘sense-experience:’ a move which, quite ironically, John Locke himself, “generally considered the father of modern empiricism,”6 would by no means have agreed with. As the author of that comment about Locke also remarks on the very same page, “In its simplest formulation, empiricism is the theory that our sense experience—seeing, touching, hearing, smelling, tasting—provides us with reliable knowledge of the world. Philosophers who stress the importance of sense experience as a primary source of knowledge are called empiricists.”7 “Rationalism,” however, “is the view that the human mind is sufficient in itself to discover truth by apprehending relations of ideas. Philosophers who stress the importance of reason or thought as the primary source of knowledge are called rationalists.”8 Another textbook has a very similar approach to rationalism, which it characterizes as “The philosophical view which appeals to reason rather than to sense impressions as the source of knowledge.”9 This is contrasted with “Empiricism: The theory that claims that all human knowledge is derived from the senses, which implies that humans neither possess inborn knowledge nor are able to generate knowledge by the use of reason alone.”10 But again there is an ambiguity: if “all human knowledge is derived from the senses” means only that all human knowledge must at first ​begin ​with sense-impressions, then the rationalists would not necessarily disagree.11 But if it means that all human knowledge is composed entirely out of the Gary Percesepe, ​Philosophy: An Introduction to the Labor of Reason ​(New York: Macmillan Publishing Company, 1991) 160. Ibid. 8 Ibid. 161. 9 Albury Castell, Donald M. Borchert et. al., ​An Introduction to Modern Philosophy: Examining the Human Condition ​(New York: Macmillan College Publishing Company, 1994) 752. 10 Ibid. 744. 11 Cf. Johannes Hirschberger, ​The History of Philosophy ​Vol.II,​ ​tr. Rt. Rev. Anthony N. Fuerst, S.T.D. (Milwaukee: Bruce Publishing Company, 1959) 88: “As a basic principle in a theory of knowledge, rationalism is not an abstract, notional philosophy nor does it mean that all knowledge originates in reason. Even its first modern representative, Descartes, attacked those philosophers who believed that, despite all the evidence of experience, truth is derived from one’s own mind as Minerva was generated from the head of Jupiter. He adds in explanation that we can practice astronomy only after we have studied the actual movement of the stars, and mechanics only after we have observed physical motion (​Rules for the Direction of the Mind, ​5). Even in Descartes’s rationalism experience is an element that must be taken into consideration.” 6 7 4 materials of sense impressions, then not even all the empiricists would agree; as was mentioned earlier, Locke would be the first to object. Locke did indeed think that all the materials of knowledge are derived from experience; but he distinguished two kinds of experience, only one of which was sensation or sense-experience. The other he called reflection, by which he meant “the internal operations of our minds perceived and reflected on by ourselves,”12 a definition that sounds suspiciously like something we would only expect a rationalist to have said, if all we knew about rationalism were the broadest characterization, or rather caricature, of it already expounded upon. But as Locke asks, Whence has [the mind] all the ​materials ​of reason and knowledge? To this I answer, in one word, from EXPERIENCE. In that all our knowledge is founded; and from that it ultimately derives itself. Our observation employed either, about external sensible objects, or about the internal operations of our minds perceived and reflected on by ourselves, is that which supplies our understandings with all the ​materials ​of thinking. These two are the fountains of knowledge, from whence all the ideas we have, or can naturally have, do spring. […] These two, I say, viz. external material things, as the objects of SENSATION, and the operations of our own minds within, as the objects of REFLECTION, are to me the only originals from whence all our ideas take their beginnings.13 Therefore Locke, the father of empiricism, accorded significant importance to an operation of reason, namely “reflection.” On the other hand Descartes, the father of rationalism, also acknowledged the significance of the role of experience in attaining knowledge.14 Where, then, is the supposed difference of emphasis between the rationalists and empiricists, when each side acknowledged the need for both reason and experience in some fashion? It should come as no surprise that the typical broad approach to rationalism and empiricism John Locke, “An Essay Concerning Human Understanding,” ed. Richard Taylor, ​The Empiricists ​(New York: Anchor Books, 1974) 10. 13 Ibid. 10-11. 14 Cf. Frederick Copleston, S.J. ​A History of Philosophy: Volume IV ​(New York: Image Books, 1963) 95: “What, then, is the rôle of experience [for Descartes]? As we have seen, it furnishes the occasions on which the mind recognizes those ideas which it draws, as it were, out of its own potentialities.” Cf. notes 11 and 35. 12 5 has resulted in a certain degree of oversimplification; for which reason it must now be supplemented with other observations of the same scope—that is, with other ‘broad,’ though perhaps more informative, observations. But it has not been without its merit. If nothing else, it has taught us that the difference between rationalism and empiricism lies somewhere in the field of epistemology.15 And yet even this statement must be qualified in order to avoid misunderstanding. Although the difference between rationalists and empiricists may be epistemological, this should not be taken to imply that epistemology as a discipline was of primary concern for both kinds of thinkers. Certainly for the empiricists it was; one need only consider the various titles of their most famous and influential works to see this point—Locke’s Essay Concerning Human Understanding, ​Berkeley’s ​Principles of Human Knowledge, ​and Hume’s ​Enquiry Concerning Human Understanding​ are all epistemological works. Indeed Locke’s express purpose in the ​Essay was “to inquire into the original, certainty, and extent of ​human knowledge,​ together with the grounds and degrees of ​belief, opinion,​ and ​assent​.”16 Now even though it remains true that epistemic concerns were of primary importance for the empiricists, one must take care not reduce their philosophies merely to such concerns. Locke, for instance, “used the principle of causality to demonstrate the existence of God, of a being, that is to say, who is not the object of direct experience;”17 Berkeley, in a surprising move, built upon his empiricism and its conclusions “a speculative idealist metaphysic, for which the only realities are God, finite minds and the ideas of finite minds;”18 whereas Hume’s empiricism moved to dismantle many key concepts of traditional metaphysics (or at least our ability to know them with certainty), such as Cf. Ibid. 28: “If we use the term ‘rationalism’ to distinguish the leading continental systems of the seventeenth and eighteenth centuries from British empiricism, we have to assign some other meaning to it. And perhaps this can most easily be done by referring to the problem of the origin of knowledge.” See also Frank Thilly, ​A History of Philosophy ​(New York: Henry Hold and Company, 1957, 3​rd​ ed.) 283: “…we may characterize philosophers as rationalists (apriorists) or empiricists (sensationalists), according to the answers they give to the question of the origin of knowledge.” 16 Locke 7, original emphasis. 17 Copleston 38. 18 Ibid. 39. 15 6 spiritual substance and causality.19 Their interests and opinions were therefore quite varied and not exclusively epistemological, even if they were primarily so. For it is still true to say that the philosophical works of the empiricists, unlike those of the rationalists, were mostly “limited to monographs on the origin and value of our cognitional processes and their products. The theoretical philosophy of empiricism is limited almost entirely to epistemology,”20 so much so that some have even seen fit to assert that “​empiricism is a kind of epistemology.​”21 The same, however, is not true of rationalism or of the rationalists in the same way. The ultimate difference between empiricism and rationalism may have been epistemological; and, when taken in this sense, rationalism would be a certain epistemological position at odds with empiricism. However, to characterize continental rationalism merely in terms of epistemology would be even more of a misrepresentation than to characterize British empiricism merely in epistemic terms. For although the rationalists may have all agreed on a certain epistemological position or assertion, their primary concerns were not, like those of the empiricists, epistemological, but rather metaphysical. To speak more precisely, the rationalists were more concerned with systematizing series of logically deduced truths, by which they intended to attain certain and demonstrable knowledge about the world, than with the nature or extent of knowledge itself. Descartes was nearly obsessed with finding the correct method or criteria for the Cf. Ibid. 39-40. Miller 248. However, Miller continues with the confusingly oversimplified statement that “[The theoretical philosophy of empiricism] is based on the principle that truth is found only in sense-cognition—that is, in experience.” But, as has been said above, Locke himself did not equate experience with sense-cognition, a fact which seems to be, not infrequently, glossed over by historians of philosophy. I say not infrequently; Copleston, for instance, does not make this mistake. Cf. Copleston 36, when he speaks from the empiricist’s viewpoint: “For factual information about the world, indeed about reality in general, we have to turn to experience, to sense-perception and to introspection.” For more on the dominance of epistemology as a philosophical discipline during the era of early modern philosophy, cf. Anthony Kenny, ​A New History of Western Philosophy, Volume 3: The Rise of Modern Philosophy​ (Oxford: Oxford University Press, 2008) 164: “Throughout the period that we have been considering, epistemology was the discipline that occupied the centre of philosophical attention: ‘What can we know, and how can we know it?’ became the key philosophical question. Indeed, the major philosophical schools are given names—‘empiricist’ and ‘rationalist’—that define them in epistemological terms.” 21 Stephen Priest, ​The British Empiricists ​(Taylor & Francis e-Library, 2007) 6, original emphasis. 19 20 7 attainment of certain knowledge; but he never defined the meaning of certitude. In other words, he was concerned with the ​possession​ of certain knowledge, not with speculation on the nature of certainty and other epistemic categories. The focus of the rationalists, if we must select a discipline, was metaphysical, not epistemological. Thus far we have only been considering the broad characteristics of rationalism and empiricism. But what of the second approach to the two, the one which is narrower and consequently more precisely defined? As was said above, this approach takes them to be specific, opposing epistemological positions. These positions, when they are expressed as such, are usually articulated by historians of philosophy as a certain stance on the possibility of existential ​a priori ​knowledge about the world.22 By ‘existential’ we mean ‘factual’ or ‘informative,’ having to do with the way things in fact exist. By ​‘a priori ​knowledge’ we understand, as the ​Stanford Encyclopedia of Philosophy​ defines it, “knowledge that rests on ​a priori​ justification. ​A priori​ justification is a type of epistemic justification that is, in some sense, independent of experience.”23 Therefore, having existential ​a priori ​knowledge about the world would It should be pointed out that although the rationalists and empiricists themselves may not have always used the term ​‘a priori’ when speaking of such knowledge (or have even used the term ‘existential’ at all),​ ​it suffices that we find in them the same meaning. They did, however, make at least some use of the terms ​‘a priori’ ​(and​ ‘a posteriori’​)​: ​cf. Benedict de Spinoza, “Ethics,” The Rationalists, ​tr. R.H.M. Elwes​ ​(New York: Anchor Books, 1960) 187, note on prop.11; Gottfried Leibniz, “Discourse on Metaphysics,” ibid., tr. George Montgomery, 417, 438; “Monadology” in ibid. 462, sec.45; 468, sec.76; George Berkeley, “A Treatise Concerning the Principles of Human Knowledge,” ​The Empiricists, ​ed. Richard Taylor​ ​(New York: Anchor Books, 1974) 159, sec.21. What terms, then, were in fact used to indicate certain kinds of ​a priori ​knowledge? On this point it is of interest to note that the dispute between the rationalists and empiricists over innate ideas, a term that was often used by both camps, is often taken to be equivalent, or at least intimately related to, the difference between them on ​a priori ​knowledge. Cf. Copleston 28, wherein he takes innate ideas and ​a priori ​truths to be interchangeable: “Philosophers such as Descartes and Leibniz accepted the idea of innate or ​a priori ​truths. They did not think, of course, that a newly-born infant perceives certain truths from the moment when it comes into the world. Rather did they think that certain truths are virtually innate in the sense that experience provides no more than the occasion on which the mind by its own light perceives their truth. These truths are not inductive generalizations from experience, and their truth stands in need of no empirical confirmation. It may be that I perceive the truth of a self-evident principle on the occasion of experience; but its truth does not depend on experience.” See also Kenny 132: “Are there innate ideas? This last question is often taken as a deciding issue: the answer a philosopher gives shows whether she [​sic​] is a rationalist or an empiricist.” 23 “​A Priori ​Justification and Knowledge,” ​Stanford Encyclopedia of Philosophy​, first published Dec. 9, 2007; accessed 18 Nov. 2009 <http://plato.stanford.edu/entries/apriori/>. 22 8 imply that some factual or informative knowledge of the world can be attained independently of experience in some way (the way being, as the rationalists would say, by deduction from intuitively grasped principles24). As might be expected, rationalism affirms and empiricism denies the possibility of existential knowledge about the world that is in a way independent of experience. For “Rationalism,” as one philosopher puts it, “is defined as the belief in the a priori as a source of knowledge of the external world.”25 Empiricism, on the other hand, while it does not necessarily deny that there is ​a priori ​knowledge, 26 or even that there is ​a priori ​knowledge about the world, does deny that there is ​existential​ ​a priori knowledge about the world—that is, ​factual ​knowledge about reality attained independently of experience in some way. Given, for example, the definition of a triangle, it follows necessarily that, ​if ​an actual triangle exists, “it must possess certain properties”—and the apprehension of the fact that the triangle in question would ​have such properties is an example of ​a priori ​knowledge about the world—“but we cannot deduce from this the conclusion that there exist triangles possessing these properties.” That is to say, we cannot deduce an ​existential​ conclusion from the definition of a triangle. “All that we can deduce is that if a triangle exists which fulfils this definition, it possesses these properties.”27 Thus not all ​a priori ​knowledge about the world is existential or factual—though it is only such ​a priori ​knowledge that empiricists deny the possibility of. The ​Stanford Encyclopedia of Philosophy​ makes the same point well in the following lucid, if rather lengthy, passage: Rationalists have typically thought that we can be ​a priori​ justified, and even know, things about the world, and empiricists have denied this. Now if the world includes abstract entities like numbers and propositions, then some rationalists, and even some empiricists, Which principles, however, were themselves at first occasioned by, but not generalized from, experience: cf. the quote from Copleston in note 22. 25 Giorgio de Santillana and Edgar Zilsel, ​The Development of Rationalism and Empiricism ​(Chicago: University of Chicago Press, 1970) 1. 26 Cf., e.g., Berkeley 159, sec.21, wherein he refers to his having previously disproved the existence of matter ​a priori. 27 Copleston 30. 24 9 will hold that we can know ​a priori​ things about the existence and nature of these entities (though the empiricists might have a different view about what it is to be an abstract entity). However, rationalists like BonJour (1998) will insist that we can also know ​a priori things about the natural world. For instance, we can know ​a priori​ that no object can be red and green all over at the same time and in the same respects, that no object can be wholly in two distinct places at the same time, and (perhaps) that backward causation is impossible. They will claim that this is knowledge of ​the nature of reality​ and will be true of any object, or event, that exists. One might grant this claim and at the same time point out that it does not give us knowledge of the existence of things, events, and states of affairs but only knowledge of what they must be like ​if​ they exist. We only know that there are objects and events in space and time by experiencing them, even if we can know a priori​ certain things about the distribution of colors on their surfaces, how many places they can be in at any given time, and whether a later event can cause an earlier one.28 It is far beyond the scope of this essay to examine the writings of each early modern philosopher on this issue individually; and so, we may proceed to agree with the following succinct definitions of rationalism and empiricism as epistemological positions provided by one recent textbook of philosophy, though perhaps with some reservations about the use made of ‘sense experience:’ Rationalism. The philosophical theory that some synthetic or existential knowledge is derived from reason rather than from sense experience, as opposed to empiricism. Empiricism […] The theory that all synthetic or existential knowledge is derived ultimately from sense experience, as opposed to rationalism.29 And though the issues raised by these and suchlike definitions could be explored in greater depth—for instance, the meaning of “derived from reason,” the question of whether the range of synthetic and existential knowledge is identical or only overlaps, or the study of each rationalist’s and empiricist’s doctrines to see how they individually manifested their opinions on ​a priori ​knowledge, existential or otherwise (and the consistency of these opinions)—it will suffice for our purposes to have assigned a “​A Priori ​Justification and Knowledge,” original emphasis. Cf. Copleston 36: “We cannot obtain factual knowledge by ​a priori reasoning. […] There is, of course, such a thing as ​a priori ​reasoning. We see it in pure mathematics. And by such reasoning we reach conclusions which are certain. But mathematical propositions do not give us factual information about the world; they state, as Hume puts it, relations between ideas. For factual information about the world, indeed about reality in general, we have to turn to experience, to sense-perception and to introspection.” 29 Wayne P. Pomerleau, ​Twelve Great Philosophers: A Historical Introduction to Human Nature ​(New York: Ardsley House Publishers, Inc.,1997) 6. 28 10 specific meaning to the terms ‘rationalism’ and ‘empiricism.’ However, it will be readily seen how, given only these definitions of the second or ‘narrow’ approach, one’s understanding of rationalism and empiricism would still be rather lacking. For what the ‘narrow’ approach to these terms has in precision, it lacks in scope; whereas what the first or ‘broad’ approach lacks in precision, it makes up for in scope. By themselves, both approaches are inadequate; but (to anticipate in a way the famous Kantian synthesis of rationalism and empiricism), when combined, the strength of the one would correct the fault of the other. Therefore, while the precise disagreement of epistemological theory outlined above in the second or narrow approach should be kept in mind as a sort of anchor or focus of the difference between rationalism and empiricism, this conception should at the same time be supplemented and contextualized by certain broad characterizations of the first approach. One should, at least, also realize the following: that the focus of the rationalists was metaphysical, but that of the empiricists was epistemological; that the rationalists all built logically deduced systems, the purpose of which was to increase our knowledge of the world, whereas the empiricists tended rather to examine cognitional notions and processes, aiming with Locke to “to inquire into the original, certainty, and extent of ​human knowledge;​”30 that the rationalists were heavily influenced and inspired by mathematics and its method of procedure, Descartes and Leibniz themselves having made significant contributions to mathematics, and Spinoza having written his ​Ethics ​in ordine geometrico​, whereas the empiricists took more inspiration for their method and content31 from the scientific findings of their day. On the one hand, The point which characterizes Descartes, Spinoza and Leibniz is rather their ideal of deducing from such [self-evident] principles a system of truths which would give information about reality, about the world. […T]heir ideal was the ideal of a deductive Locke 7, original emphasis. Cf. Berkeley, 137, sec.4: “And surely it is a work well deserving our pains to make a strict inquiry concerning the first principles of human knowledge, to sift and examine them on all sides…” 31 Though of course Descartes, for instance, was influenced by the findings of empirical science and made various scientific contributions himself (for example, his work on ​Optics​). 30 11 system of truths, analogous to a mathematical system but at the same time capable of increasing our factual information.32 But on the other, the nature of empiricism is revealed most clearly in its historical development, since it is possible to regard this development as consisting, in large part at least, in a progressive application of the thesis, enunciated by Locke, that all our ideas come from experience, from sense-perception and from introspection.33 One particularly articulate and helpful historian of philosophy, taking Descartes as the founding figure of rationalism and Francis Bacon as the most significant forerunner of empiricism, makes the case that Bacon developed a philosophy which sought to arrive at truth through induction and the methodology of controlled experiment while Descartes developed a philosophy which sought to arrive at truth through deduction along the lines of mathematical reasoning. Bacon’s method would give rise to a school of philosophy called ‘empiricism,’ while Descartes’ method would engender a school of philosophy called ‘rationalism.’34 As long as one keeps in mind the balancing truth that Descartes himself performed experiments and did not in any way simply discount the evidence of sense experience35—the full title of his ​Discourse on Method Copleston 29. Ibid. 37. 34 Anthony E. Gilles, ​The Evolution of Philosophy​ (New York: Alba House, 1987) 101. Cf. 101-2: “Like Bacon, Descartes, too, mistrusted the senses as a means to truth. But, unlike Bacon, he preferred to rely not on controlled experimentation as the means to truth, but on intuition and deduction. In other words, whereas Bacon relied on an external method to achieve truth, Descartes relied on an interior method. Whereas Bacon relied on instrumentation and experiment to aid the senses in the observation of material reality so that the mind could formulate correct conclusions through the process of induction, Descartes believed that the mind itself, properly directed, could enable one to deduce ​a priori ​truths without reliance on observation and experiment. Descartes was in this sense a ‘rationalist’ while Bacon was the forerunner of empiricism.” Gilles is one of the more cautious historians of philosophy that we have found; see also 123: “At the start of the last chapter we noted the Francis Bacon’s philosophy could be said to have stimulated the development of British empiricism. Like any generalization that one was helpful for purposes of organizing our thought, but may have unduly simplified matters. […] Thus in this chapter, although we will notice that the focus of philosophy certainly changes, we should not think that the British empiricists are completely at odds with the presuppositions of continental rationalism.” 35 Cf. Copleston 93: “Descartes’ ‘pan-mathematicism’ is thus not absolute: he does not refuse to allow any role to experience and experiment in physics. At the same time it is noticeable that the part which he assigns to verificatory experiment is to supply for the limitations of the human mind. In other words, although he does in fact give experiment a part to play in the development of our scientific knowledge of the world, and although he recognizes that we cannot in fact discover new particular truths in physics without the aid of sense-experience, his ideal remains that of pure deduction. He can speak scornfully of natural philosophers who disdain any appeal to experience because he recognizes that we cannot in fact dispense with it. But he is far from being an empiricist. The ideal of assimilating physics to mathematics remains always before his eyes…” See Descartes 36, sec.64 of the Sixth Part of the ​Discourse​. 32 33 12 was ​Discourse on the Method for Rightly Conducting One’s Reason and for Seeking Truth in the Sciences​—this is a very useful observation. For, as the same historian of philosophy points out, Descartes did indeed acknowledge the significance of the role of experience, and in particular of sense-experience, as “a sort of catalyst” for knowledge. Descartes did not mean to exclude experience as a means to knowledge, but he gave to it only an incidental role in the process of arriving at truth. For Descartes, the principal function of sensory experience is to trigger the process of intuition and deduction. […] Thus, for Descartes, sensory experience is not unimportant, but it is not the means to knowledge; rather, it is a sort of catalyst for the actual process of acquiring knowledge, namely, intuition and deduction.36 With all of these observations having been made, and with the strengths of both approaches to rationalism and empiricism thus having been combined, we can with confidence say that it is indeed possible to define these terms in such a way that they are a significant aid to our understanding of early modern philosophy. But this is only the case because the effort has been made to set out in sufficient detail the major issues involved; were one presented with only one of the two approaches, or worst of all with only the broadest caricature of the first approach, one that merely associates ‘reason’ with the rationalists and ‘experience’ with the empiricists, then little understanding would have been gained. Only a synthesis of both approaches can produce an adequate understanding of early modern philosophy. Nevertheless, even with an adequate grasp of the main issues involved, it must always be remembered that the terms ‘rationalism’ and ‘empiricism’ have been retroactively imposed, and, like any classifications, do not do complete justice to their individual members—in this case, to each particular early modern philosopher. For Gilles 103. Cf. note 11; see also Hirschberger 187: “It is true, of course, that rationalism paid less heed to experience than did empiricism. But this attention to experience is in itself only a practical question which can be solved without too much trouble. The more important difference between the two systems lies in the evaluation each gives to experience, by which we understand sense experience. Rationalism viewed such experience as the prelude, the introduction to truth; it considered such experience as necessary only to provide the material for knowledge. According to rationalism, knowledge and truth are perfected only within the mind and are attained by an intellectual perception of essences. Empiricism, on the other hand, considered sense experience as perfect and complete in itself, as the sum total of human knowledge and philosophy.” 36 13 this very reason, nothing should replace an encounter with the thought and writings of the philosophers themselves, and likewise the history of philosophy should, ideally, never be studied as a mere substitute for such an encounter. But if any work in the history of philosophy has moved some to study the philosophers themselves, and thus to philosophize along with them, then it has accomplished its highest goal. 14