This paper is an attempt to show how Kants ideas concerning practical and transcendental freedom of the will was a significant correction to the parallel theories of Hume. It starts out by clarifying Humes critique of free will, especially as it appears in An Enquiry Concerning Human Understanding. It draws the conclusion that Humes philosophy is espousing skepticism, and that Kants effort is to overcome this skepticism and restore trust in reason. The philosophy of Kant is outlined in order to make the last point.
It is generally agreed that Kant supplied the definitive stamp to philosophy that ushered in the modern age. Hume, though enormously influential in his time, and a favorite in the French salons of philosophy, fell into disrepute in the Victorian era, and only since has become a subject of restored interest. Yet Hume is the philosopher cited by Kant as having stirred him from his dogmatic slumbers. He had espoused a philosophy of empirical skepticism, so thorough and devastating in its scope that it became impossible for Kant to remain in his settled certainties of Newtonian science. It was the spur that carried him on to compose the Critique of Pure Reason (1781), where reason is restored, and man is once more vindicated as a rational being.
Just because he refuted and answered Humes skepticism does not imply that the latter philosophy is nullified. We must keep this in mind, that Humes skepticism is completely valid as far as sense experience is concerned, and Kant does not refute any part of this philosophy. What he does is posit a further dimension to human understanding, specifically, the synthetic a priori faculty of the mind, the existence of which Hume did not suspect. Only after this addition is the primacy of reason restored. So we cannot say that Kant has destroyed Humes philosophy, rather he has added to it.
Central to Humes skepticism is his critique of cause and effect, which is spelled out to its most profound depths in chapter VII of the An Enquiry Concerning Human Understanding (1748). The preliminary task is to outline the copy principle. The premise to this is that all knowledge begins from sense experience. Among such we are able to distinguish between primary and secondary sensations. The primary sensations are extension, motion, inertia etc, which are indeed the concepts that physics tackles. Color, taste, smell etc are said to be secondary sensations, composed or derived from the primary ones.
The copy principle says that the primary sensations, though not delivering complete information from the material object which is more poignantly described as the object in itself nevertheless is a faithful copy of it. This is why primary sensations are distinct and forceful presences in our mind. Secondary sensations are in turn copies of the original copy, and due to this derivative nature they lose distinctness to us. We will examine the copy principle of Hume in a moment.
For the time being we accept it as such and consider the consequences. For Humes purposes, it has allowed him to refer to objects and their motions with confidence, and not to be held back by the validity of these concepts. For without the principle we dont know as yet that objects are objects, and motion is motion, and we would have had to deal with a chaos of sense experience, and nothing meaningful to refer to it against (1993, p. 12).
So now, with the copy principle of Hume as foundation, we proceed to talk about objects in motion. Next, we observe interdependence between objects, carried out in space and time. We know that motion in one object is cause to motion in another.
A billiard ball in motion strikes another, and after impact the second acquires a velocity too, and the faculty of our understanding tells us, without the least inkling of doubt, that the impact imparted by the first ball is the cause of the second ball gaining motion. This understanding is so refined that we can, with a little help from Newtons mechanics, predict the exact trajectory of the second ball by analyzing the trajectory of the first. We know it, but how do we know it? This is the crucial question for Hume. For if we do not have the answer we are left with skepticism.
After impact with the first ball the second could have taken any one of an infinite number of trajectories. But it takes only one, and indeed we expect it to take only that one. A physicist may come along and try to convince us that it could not have taken any other trajectory because the laws of motion stipulates that, with the initial conditions given, the path it takes is the only possible one. But this is not an answer to the observer of the billiard ball, because he doesnt care what the laws of physics are. If nature had followed another mathematical law then another outcome would have been just as valid.
The observer could then have framed his conundrum differently: Of the infinite possible mathematical laws why just that one? There is nothing in the inner logic of the situation that dictates that the first ball should produce exactly the prescribed trajectory in the second. Hume said this about the experimental set-up, that we may try an experiment ten times, and may arrive at the exact same result ten times. But this does not prove that the specific outcome is inevitable. Not even if we confirmed the outcome a million times, because we would still only have a statistical probability and not a proof.
Humes conclusion is that there is no rational link between cause and effect. Yet we expect effect to follow cause, immediately and irrevocably. If this is so then, explains Hume, it is a feeling transmitted to us by custom. What exactly he means by custom is left vague. He could not have meant anything other than observing over and over again, even though this fails to take into account new experience.
He himself supplies a famous counterexample in the Enquiry. Some one who has experienced all the shades of blue, except for a tiny strip of the spectrum, is expected to report a gap when looking at the full spectrum of blue. But the fact is that he does not observe a gap at all, and recognizes at once the full spectrum of blue, even though he is experiencing a particular shade on blue for the first time. The recognition was instantaneous, and the eye did require accustoming beforehand. This readily disposes the theory of custom. Hume, however, continues to insist that our convictions regarding cause and effect can have no other source than custom.
That the inference to custom is a vague one is made clear when he comes to consider free will. The very act of consciousness, he says, testifies to the existence of free will. But coming to reflect on how it is possible that we are able to willingly set our limbs into motion, and to move and external object thereby, it appears nothing less than miraculous. The mystery in nothing less than how one immaterial body imparts momentum to another:
For first: Is there any principle in all nature more mysterious than the union of soul with body; by which a supposed spiritual substance acquires such an influence over a material one, that the most refined thought is able to actuate the grossest matter? (Hume, 1993, p. 43)
The upshot is that we cannot explain free will, just as surely as we cannot explain cause and effect. Custom was hesitantly introduced to explain cause and effect, and the same comes to the rescue of free will. As constant observers of nature we come to expect an effect to always follow a cause, and the same analysis ought to be applied to the orbit of human will. In all times and in all places humans have shown a constancy in their day to day affairs, which points to a constancy in human nature. The speculation concerning the scope of free will is overdone by the philosophers, maintains Hume.
The exercise of free will, when looked at through the vista of human history, does not display divergence as much as it displays constancy. Hume broaches on the distinction between freedom and necessity to make this point clear. Inanimate objects convey to us most clearly the quality of freedom. We may describe an inanimate object as indifferent to the rest of the material universe, and in that sense free. But this freedom also entails necessity. The object is subject to the necessary laws of causation, and indeed is bound entirely by them. This is the relationship that binds cause and effect to inanimate objects, and is a relationship that is composed of both freedom and necessity.
Hume transposes the same analysis to the relationship between human beings and free will. The will is indeed free, but being so implies that it conforms to human nature. He proposes the following definition:
By liberty, then, we can only mean a power of acting or not acting, according to the determinations of the will; this is, if we choose to remain at rest, we may; if we choose to move, we also may. (1993, p. 63)
The notion of free will advanced here bears a crucial difference to the popular one, and begs to be spelt out. What Hume describes as free will is not a choice between course A and B. Rather the choice is between A and not A, the latter implying stagnation, not an alternative course. This is the entire extent of our free will. We choose either to move forward, or else to stand still. This is what Hume would describe as freedom to act. Free will, however, is in complete accordance with human nature, and therefore follows the laws of necessity, just as everything else in contingent reality. Free will urges us to act freely. With freedom to act we may respond to this urge, or we may desist.
In the final analysis our understanding of free will hinges on custom, in the same way as does our understanding of cause and effect. The past is guide to the future in the probabilistic sense. Beyond probabilities we have no understanding of either, contends Hume. In order to enforce this skepticism he proceeds to dismantle the Cartesian theories that pretended to explain mind and matter interaction, especially the theory of occasionalism advanced by Father Nicholas Malebranche.
In this theory God is made both motivator and executor of every act or incident that seems to be cause, while the circumstances which we call a cause are only occasions for God to act in such a manner. Hume complained that this not only made God a slave to his own creation, but it also eradicated free will, making everything full of God (1993, p. 47). By disposing summarily the Cartesian explanations of cause and effect Hume makes his skepticism complete.
Kant overcomes this skepticism by revising the premise of Hume. The correction is made most forcefully in the opening to the Critique:
Although all our knowledge begins with experience, it does not follow that it arises entirely from experience. For it is quite possible that our empirical knowledge is a compound of that which we receive through impressions and that which our own faculty of knowing (incited by impressions) supplies from itself¦ (1999, p. 1)
To be fair to Hume, he does consider this possibility, and ponders whether there is a blueprint in the mind where all causes and all effects can be referred back. (1993, p. 44). But he dismisses this idea when he realizes that a static blueprint can never account for the dynamic reality. However, the faculty that Kant is suggesting is not static, rather dynamic and creative, and here lies the crucial difference. In the technical terms of Kant it is the synthetic a priori faculty of the mind. This is distinguished from the analytic a priori faculty, such as logic. The rules of logic are extant in the mind (a priori), but form a self-consistent system (analytical), and therefore do not depend on sense experience.
On the first instance it seems impossible that the mind can have a faculty that is synthetic a priori, where synthetic implies that it is creative. It entails that order is created out of the chaos of sense experience, and order that was not there before. But Kant also provides proof that the mind is capable of synthesis. Mathematical propositions are synthetic a priori, he contended. The proposition 3 + 5 = 8 may sound like self-consistent logic, but it is not really so. 8 is a completely new concept, and is not contained in either 3, 5 or +. If we know that 3 + 5 = 8, it is due to a synthetic a priori faculty in the mind.
As Kant relates in the Prolegomena, when he realized that mathematical propositions are indeed synthetic a priori, it led him to ponder on what other such concepts the mind uses to facilitate understanding, and it appeared to him, in due course, that cause and effect was a concept of understanding that derives from the same faculty. He does not at all concern himself with material reality as a thing in itself, that which the materialist philosophers were after in order to provide a foundation to Newtonian science. Like Hume he maintains throughout that an absolute material reality is beyond knowledge, and to speculate on its existence was futile.
We only need to consider what we perceive and what we do. He also shows that Hume falters at exactly those points where he cannot dismiss material existence in itself. The copy principle is slavish to a material object in itself. The object does not deliver copies to our mind; rather the mind provides the concepts of space in which we are able to conjure up material objects from sensory data. Both space and time are pure concepts of the mind, contends Kant, and like cause and effect are the tools by which we come to understand contingent reality (Prolegomena, 2005, p. 26).
As soon as it is made out that we are the responsible architects of our own reality, and are not passive bystanders to an absolute material reality beyond our control, we suddenly discover ourselves as moral beings. Therefore the subsequent direction of Kants philosophy, after the metaphysics of understanding has been established, is towards a metaphysics of morals.
And so emerges the crucial distinction that Kant makes between practical and transcendental freedom. To say that we have practical freedom implies we are able to understand the world, and by doing so we direct the will accordingly. We will do so of course for practical purposes survival, utility, convenience, happiness etc. this would seem to cover the entire orbit of freedom. But Kant went on to demonstrate, in his Groundwork for the Metaphysics of Morals (1785), that such freedom is not actually freedom at all, and indeed is a binding. Thus far Kant is in concord with Hume.
Now, the metaphysics of understanding, as spelt out in the Critique, is not the entire picture. The synthetic a priori faculty of the mind fashions understanding out of sensory experience. But such understanding does not lead to truth. As pure concepts of understanding space and time are both necessarily infinite. But because they emanate from the finite mind they are also finite. So in their very make-up space and time lead to contradictions. The same end must necessarily meet anything that takes place within space and time. So that matter is both infinitely divisible and also made up of concrete building blocks.
As another example, we have free will, but at the same time everything is caused, so we dont have free will. Such examples are put forward by Kant as pairs of antinomies. According to our understanding both consequences are valid, and yet they mutually contradict each other. All practical reasoning necessarily leads to pairs of antinomies.
This must be so, because we reason by means of subject and predicate, where the subject is the cause of the predicate. But this subject is in turn predicate to another subject, and so on in an infinite chain of causation. If there was an ultimate subject at the beginning of this chain, we could have claimed to have discovered the final cause, and thereby have at hand a pronouncement of truth. But in contingent reality there is no such final cause. So whenever we try to make pronouncements of truth we must face contradiction.
We cannot say that practical reason is false for this reason. Life is ruled by contingencies, and practical reason is to explain the contingent, or to facilitate such understanding. Absolute truth lies beyond all contingencies, and this is ruled by pure reason, explains Kant. It is not within the grasp of the human mind, yet it is the underpinning of the mind, and is the source of all innate faculties.
The same analysis applies to practical freedom, which is but the corollary to practical reason. With practical freedom we choose our course according to practical reason, i.e. we are motivated by self-serving motives happiness, honor, respectability, and so on. But in doing so we bind ourselves to those endless chains of contingencies, so that we are not really free. We chase material acquisition in order to be happy, and yet it always eludes us. The definition of freedom is to escape all contingencies, and yet by the application of practical reason we are mired more and more into contingent reality. Therefore we are not free.
This is indeed a contradiction, one which Hume does not pay heed to. The very act of consciousness tells us that we are free, that out will is free. If practical reason does not embody this freedom, then surely pure reason must do so. By the same token, we are in possession of a transcendental freedom, which is a path that overcomes all contingencies, and is dictated by pure reason. Kant describes this path as the moral one. We recognize and follow this path from a sense of duty.
To clarify what it is, duty is done for its own sake. There is no material motive whatsoever attached to it. Not for any particular good, it is done for the universal good. It is a categorical imperative, meaning that the very make-up of our being, or pure reason, dictates that we follow it. As an aid to identifying ones duty Kant devised the following wording for the categorical imperative: I ought never to act except in such a way that I could also will that my maxim should become a universal law (Moral Law, 2005, p. 74).
Kant is described as overcoming Humes skepticism. But it is questionable whether the latter is a skeptic at all. According to a contemporary, Humes philosophical paradoxes are delivered with a confidence that belies skepticism: Never has there been a Pyrrhonian more dogmatic (qtd. in Mossner, 1936, p. 129). A more recent reassessment of Hume is carried out by the German Neo-Kantian philosopher Ernst Cassirer, who opines, Humes doctrine is not to be understood as an end, but as a new beginning (1951, p. 59).
The nature of this new beginning is well articulated by Hume himself. Indulge your passion for science, nature tells us, according to Hume, but let your science be human, and such as may have a direct reference to action and society (Hume, 1993, p. 3). If we listen carefully, the moral note that Hume is sounding is hardly different from that of the categorical imperative of Kant. Not for the persons sake, but for humanitys sake. Not for the particular good but for the universal good. This is the essence of Humes projected science of man, as it is also the heart of Kants metaphysics of morals.
Cassirer, E. (1951). The Philosophy of the Enlightenment. Trans. Fritz C. A. Koelln and James P. Pettegrove. Boston: Beacon Press.
Hume, D. (1993). An Enquiry Concerning Human Understanding. E. Steinberg (Ed.) Boston: Hackett Publishing.
Kant, I. (1999). Critique of Pure Reason. W. S. Pluhar (Trans.), E. Watkins (Ed.) Boston: Hackett Publishing.
Kant, I. (2005). Kants Prolegomena to Any Future Metaphysics. Whitefish, MT: Kessinger Publishing.
Kant, I. (2005). The Moral Law: Groundwork of the Metaphysic of Morals. Translated by H. J. Paton. New York: Routledge.
Mossner, E. C. (1936). Bishop Butler and the Age of Reason: A Study in the History Of Thought. New York: Macmillan.