Immanuel Kant on Skepticism
Immanuel Kant was bom in 1724 in Königsberg, which then was the capital of East Prussia and mainly Gemtan speaking, but which nowadays is called Kaliningrad and is part of Russia. He did not grow up in poverty but his parents were harness makers and had a very modest income. They were pietists, which is a version of Lutheranism. Kant also attended a pietist school between the ages of 8 and 15. He supposedly hated his time there and instead devoted much of the time to reading the Ancient classics.
His time at the University of Königsberg was, however, much better and his interest in classical literature was soon transferred to philosophy. Kant studied mathematics and physics together with philosophical subjects like metaphysics, logic, ethics, and natural law. The philosophers that were Kant’s teachers were deeply influenced by Christian Wolff (1679-1750), who defended a systematized version of Leibniz’s philosophical thinking, but Kant was also exposed to Aristotelian philosophy and the British empiricists’ criticism of Wolff.
After he finished university in 1748, he spent the next six years as a private tutor to young children. He returned to the university in 1754 and began teaching. Upon returning, Kant published several scientific works. His position at the university was as an unpaid lecturer, which meant that he had to get paid directly by the students. To be able to earn a decent living, he had to teach a very high course load and also work to attract students to his classes. During this time, he lectured about 20 hours a week. He held this position until 1770. He was, however, quite successful and his reputation as a brilliant philosopher grew steadily during this time.
Between 1762 and 1764, Kant published several works, which by scholars nowadays are counted as belonging to an earlier period in Kant’s philosophical development. They more or less contribute to the kind of philosophy he grew up with and was taught during his time as a student in Königsberg. In 1770, Kant was appointed to the Chair of Logic and Metaphysics at the University of Königsberg, a position he held until 1796 when he retired from teaching at the age of 72.
A few years before his appointment as Professor, in 1766, Kant had published his first work that asked questions about the possibility of metaphysics. It is Dreams of a Spirit-Seer Elucidated by Dreams of Metaphysics, which is first and foremost a criticism of Emanuel Swedenborg (1688-1772), the Swedish visionary, who claimed to have insights into the spirit world and made a series of predictions that got enormous attention and a large following - a following which continues even today — but it is also a criticism of traditional metaphysics. Kant had a few years before this book was written read Hume’s first Enquiry, which had been translated into French.
As part of his new position as Chair of Logic and Metaphysics, Kant got more time to write and it is now he begins to develop the thinking that was to make him one of the foremost philosophers to have ever lived. In 1781, he published Critique of Pure Reason, in which he argued that our understanding supplies the forms by which we structure our experience of the world, and to which human knowledge is limited, while the world of things in themselves is totally unknowable. He spent over a decade developing this completely new way of approaching knowledge and experience. Having published the first Critique, Kant published a number of groundbreaking works in a very short period of time. In 1783, he published A Prolegomena to Any Future Metaphysics; in 1785, Groundwork of the Principles of Morals; in 1786, Metaphysical Foundations of Natural Science; in 1787, a second, substantially revised edition of Critique of Pure Reason; in 1788, Critique of Practical Reason; and in 1790, Critique of the Power of Judgment. He continued to publish and to develop his new version of philosophy until 1798. This period of hrs philosophical thinking is often referred to as the critical period. Kant died in 1804, almost 80 years old.
We cannot here give a general presentation of Kant’s philosophical thinking, but instead merely look at how he dealt with skepticism and what kind of influence skepticism could have had on him. There are, foremost, three aspects of Kant’s later philosophical thinking that relate to skepticism. First of all, there is the influence of Humean skepticism on Kant, which was substantial. Secondly, there is a curious influence of Pyrrhonian thinking as well. Thirdly, there is Kant’s famous refutation of idealism or refutation of Cartesian external world skepticism.
In the Preface of the Prolegomena to Any Future Metaphysics (henceforth. Prolegomena), Kant writes that it was Hume that “first interrupted my dogmatic slumber and gave a completely different direction to my research in the field of speculative philosophy” (Prolegomena: 10). As he admits in the passage, where this sentence is embedded, it was Hume’s skepticism towards, in particular, causality that motivated Kant to rethink metaphysics. In the Preface, he also objects to the common sense philosophers who, in his words, never realized that to come to terms with the problem Hume had pointed to one would have to “penetrate very deeply into the nature of reason”, but instead they simply appealed to common sense “as an oracle when one knows of nothing clever to advance in one’s defense”. Instead, what was needed, according to Kant, was what is really the basis of the whole critical philosophy, namely, the realization that concepts like causality are not derived from experience, but are instead a priori (before experience) categories through which our understanding thinks about things and which really construct our experience. These categories are what Kant calls synthetic a priori and the metaphysical question motivated by Hume’s skepticism is: how is synthetic a priori knowledge possible? The answer to this question encompasses much of Kant’s theoretical philosophy.
The topic of the Prolegomena is this very question and for Kant only a positive answer to it stops Humean skepticism in its tracks and also makes metaphysics possible. Throughout his life, Kant seems, foremost, to have thought about skepticism as an attack on metaphysics. Already in Dreams of a Spirit-Seer that view of skepticism appears. There is a scholarly debate as to whether the kind of skepticism Kant was influenced by in that work was Pyrrhonian or Humean in nature. The work certainly coincides with Kant’s reading of Hume, but neither Hume nor Pyrrho is mentioned in the book. He, however, expresses a Humean view of causality in the work. He writes, “Questions like ‘How something can be a cause, or possess a power’ can never be decided by reason, but these relations must be taken from experience alone.” Such consideration provides him with grounds for rejecting metaphysics, and what his rejection of Swedenborg’s spiritual world reveals is exactly this lack of justification or rational grounds for metaphysics. How can metaphysics be given a firmer foundation and clearer focus than the spirit world of Swedenborg? It is this skeptical question that motivates Kant going forward and his answer becomes synthetic judgments a priori.
The discussion in the Prolegomena, which is a more easily readable summary of what he already developed in the first Critique, is divided into four sub-questions, namely (1) how is pure mathematics possible?, (2) how is pure natural science possible?, (3) how is metaphysics in general possible?, and (4) how is metaphysics as a science possible? All four of these are versions of the overall question about synthetic judgments a priori and their answer provides answers to the general questions. The issue of causality comes up, foremost, in the answer to the second question. According to Kant, natural laws and causality are synthetic a priori. He writes:
The concept of cause is therefore a pure concept of the understanding, which is completely distinct from all possible perception, and serves only, with respect to judging in general, to determine that representation which is contained under it and so to make possible a universally valid judgment.
(Prolegomena: 52)
On this view, causality is a concept distinct from and prior to all experience, and, hence, not derived from experience, as Hume argued and Kant himself thought in Dreams of a Spirit-Seer. It is in this sense that it is a priori, according to Kant, that is, before experience. It is a condition on experience, which also makes it necessary, since it is the way we have to experience the world. We are bound by concepts like causality to experience the world in a certain way. Kant’s response to skepticism about causality is to say that it is not derived from experience but a condition on experience. This is what is called Kant’s Copernican turn in philosophy. It is quite ingenious, but, before he can declare mission accomplished, he needs to prove or deduce these categories, that is, prove that they exist and do the job that they are supposed to do, which he also does in the first Critique. This deduction is very controversial, however, and one of the most difficult parts of Kant’s later philosophy. We cannot go into it here.
The second influence of skepticism on Kant is a bit curious. It is here labeled as the influence of Pyrrhonism on him, but Pyrrhonism is very little talked about in Kant’s philosophical works. Let us firstly dwell a little on what he says about skepticism. In a longer passage from Die Blomberg Logic, which brings together Kant’s lectures on logic from the early 1770s, he develops his view on skepticism and its history. He begins by contrasting dogmatic and skeptical philosophy. He sees himself, foremost, as a dogmatic thinker, but he is not entirely dismissive of skepticism. With an eye to Sextus Empiricus, he notes that skepticism or doubt — he seems to equate those - can also be dogmatic. The contrast he has in mind is the one between the Academics and the Pyrrhonists. The Academics are dogmatic skeptics, according to him, whereas a Pyrrhonist on the other hand is a skeptical doubter, who holds that each and every one of our judgments may be opposed. Dogmatic doubt consists, for Kant, in judging that one can never attain complete certainty with a cognition. Skeptical doubt consists in being conscious of the uncertainty of one’s cognitions. The latter compels one to inquire more about it and perhaps arrive at certainty. He makes a lot of the meaning of the Greek word for skeptic, which as we saw in Chapter 1 means ‘to inquire’ or ‘to investigate’.
It is in this positive vein that one might argue that Pyrrhonism had some influence on Kant’s later philosophy. In the first Critique, the part on the ‘Transcendental Dialectic’, chapter 2, Kant develops what he calls ‘The Antinomy of Pure Reason’. The antinomies are contradictions or equipollences, as the Pyr-rhonian skeptic would call them. Kant writes in the Critique:
Here a new phenomenon of human reason shows itself, namely a wholly natural antithetic, for which one does not need to ponder or to lay artificial snares, but rather into which reason falls of itself and even unavoidably; and thus it guards reason against the slumber of an imagined conviction, such as a merely one-sided illusion produces, but at the same time leads reason into the temptation either to surrender itself to a skeptical hopelessness or else to assume an attitude of dogmatic stubbornness, setting its mind rigidly to certain assertions without giving a fair hearing to the grounds for the opposite. Either alternative is the death of a healthy philosophy, though the former might also be called the euthanasia of pure reason.
(Critique: 460)
These are true conflicts within reason itself and it is faced with a skeptical stalemate or “slumber”. Kant distinguishes what he is doing from skepticism, however. He writes that:
this procedure, I say, can be called the skeptical method. It is entirely different from skepticism, a principle of artful and scientific ignorance that undermines the foundation of all cognition, in order, if possible, to leave no reliability or certainty anywhere. For the skeptical method aims at certainty, seeking to discover the point of misunderstanding in disputes that are honestly intended and conducted with intelligence by both sides, in order to do as wise legislators do when from the embarrassment of judges in cases of litigation they draw instruction concerning that which is defective and imprecisely determined in their law.
(Critique: 468—469)
It is the skeptical method of the Pyrrhonists that Kant is using, and his goal is to find certainty through it.
Kant’s antinomies are famous and have been a central part of philosophy ever since he formulated them, and before him as well, since they, for that matter, are old philosophical problems. The third antinomy is the conflict between the thesis: “Causality in accordance with laws of nature is not the only one from which all the appearances of the world can be derived. It is also necessary to assume another causality through freedom in order to explain them,” and the anti-thesis: “There is no freedom, but everything in the world happens solely in accordance with laws of nature.” At the same time that there is an absolute need for freedom and free will to account for moral responsibility and the existence of morality in general, Newtonian mechanics excludes freedom, since everything follows from a set of laws of nature. According to Kant, reason is transfixed by this contradiction and the skeptic’s way out to simply suspend judgment is not an option for Kant. There has to be a way forward, otherwise reason itself has collapsed and failed. Kant’s famous solution is to make freedom a postulate - a practical postulate -which we cannot know exists, but that we have to postulate to exist as a thing-in-itself, that is, it is beyond experience and serves as a condition for our existence.
The fourth antinomy is very similar and equally famous. It is about the existence of God, and the antinomy arises in a conflict between the following statements:
Thesis: “To the world there belongs something that, either as part of it or as its cause, is an absolute necessary being.”
Anti-thesis: “There is no absolute necessary being existing anywhere, either in the world or outside the world as its cause.”
In his discussion of this antinomy, he develops arguments for and against a cosmological argument for the existence of God. It is a classical piece of philosophy. Again, his solution ultimately becomes to make God a postulate as well and part of the thing-in-itself. God becomes necessary, but beyond experience.
The third discussion of skepticism in Kant is perhaps the most famous one, namely, his rejection of idealism or, which for him amounts to the same thing, rejection of Descartes’ skepticism about the external world. Kant distinguishes his own idealism, that is, what he calls transcendental idealism, from what he names material idealism. There are two kinds of such idealism, namely, one that declares the existence of objects outside us to be doubtful or indemonstrable, and another that declares objects outside to be false and impossible. The second kind is the idealism of Berkeley. He calls it dogmatic idealism and writes that it:
declares space, together with all the things to which it is attached as an inseparable condition, to be something that is impossible in itself, and who therefore also declares things in space to be merely imaginary. Dogmatic idealism is unavoidable if one regards space as a property that is to pertain to the things in themselves; for then it, along with everything for which itserves as a condition, is a non-entity. The ground for this idealism, however, has been undercut by us ...
(Critique: 326)
He thinks his own philosophy has proven dogmatic idealism to be false. It is the first kind of idealism he is concerned with in his refutation. He calls this kind of idealism problematic and attributes it to Descartes. He writes that:
Problematic idealism, which ... professes only our incapacity for proving an existence outside us from our own by means of immediate experience, is rational and appropriate for a thorough philosophical manner of thought, allowing, namely, no decisive judgment until a sufficient proof has been found. The proof that is demanded must therefore establish that we have experience and not merely imagination of outer things, which cannot be accomplished unless one can prove that even our inner experience, undoubted by Descartes, is possible only under the presupposition of outer experience.
(Critique: 326)
Kant sets out to prove the existence of an external world, and, hence, also reject Descartes’ doubt.
The proof itself is very controversial and much discussed. It is fairly short. The theorem to prove is the following:
The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me.
The proof is in Kant’s words the following:
I am conscious of my experience as determined in time. All time-determination presupposes something persistent in perception. This persistent thing, however, cannot be something in me, since my own existence in time can first be determined only through this persistent thing. Thus the perception of this persistent thing is possible only through a thing outside me and not through the mere representation of a thing outside me. Consequently, the determination of my existence in time is possible only by means of the existence of actual things that I perceive outside myself. Now consciousness in time is necessarily combined with the consciousness of the possibility of this time-determination: Therefore it is also necessarily combined with the existence of the thing outside me, as the condition of time-detennination; i.e., the consciousness of my own existence is at the same time an immediate consciousness of the existence of other things outside me.
(Critique: 321)
There have been many attempts at reconstructing this argument and they are all slightly different. A common and oft-used way of summarizing the argument is the following:
- 1. I am conscious of my own existence in time; that is, I am aware, and can be aware, that I have experiences that occur in a specific temporal order, (premise)
- 2. I can be aware of having experiences that occur in a specific temporal order only if I perceive something permanent by reference to which I can determine their temporal order, (premise)
- 3. No conscious state of my own can serve as the permanent entity by reference to which I can determine the temporal order of my experiences, (premise)
- 4. Time itself cannot serve as this permanent entity by reference to which I can determine the temporal order of my experiences, (premise)
- 5. If (2), (3), and (4) are true, then I can be aware of having experiences that occur in a specific temporal order only if I perceive persisting objects in space outside me by reference to which I can determine the temporal order of my experiences, (premise)
- 6. Therefore, I perceive persisting objects in space outside me by reference to which I can determine the temporal order of my experiences. (From (1)—(5))
The idea behind the proof is to turn the table on the idealist. Kant wants to show that the idea of an inner experience, which is not doubted by Descartes, actually presupposes the experience of external objects, that is, the experience itself is conditioned upon the experience of something as external. The way Kant seems to do this is to talk about past experience that we can order in time. Given that I can do this there must be something that I do this against or from. Now, this something cannot be something in me, it must be something outside of me. Hence, my past experience ordered in time is conditioned upon the existence of things outside of me.
The argument seems to have a serious flaw, however, that many commentators have pointed out. The temporal order mentioned in (2) seems simply to be the order in which I had those experiences. It seems relevant to ask why I should need any “persisting element” or something external to me to know what this order is. There have been several attempts at rescuing the argument. Some have suggested that the mere occurrence of this temporal order is not the same as the recognition of the temporal order as an ordering and that it needs something more persisting or external to my experience, but this does not seem sufficient. There are other more elaborate attempts to save the argument, but we cannot get into those here.
A persistent feature of Kant’s view of skepticism is its metaphysical nature. Throughout his life, he seems to view skepticism, foremost, as a challenge to metaphysics. This seems to be the way he interprets Hume’s skepticism, that is, as an argument against traditional metaphysics. It is not wrong to think of Hume in that way. His repeated emphasis on empiricism and the starting point of all philosophy in impressions poses special problems for traditional metaphysical views about substance, immortality, God, and causality, as we have seen. It is that challenge that Kant took up in his critical philosophy and mounts a defense of — a defense that became enormously influential in the following centuries.
