A Critical Assessment of Immanuel Kant's Epistemological Alternative to Hume's Fork
All the objects of human reason or enquiry may naturally be divided into two kinds, to wit, Relations of Ideas and Matters of Fact. Of the first kind are the sciences of Geometry, Algebra, and Arithmetic; and in short, every affirmation which is either intuitively or demonstratively certain. That the square of the hypotenuse is equal to the square of the two sides, is a proposition which expresses a relation between these figures. That three times five is equal to the half of thirty, expresses a relation between these numbers. Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is anywhere existent in the universe. Though there never were a circle or triangle in nature, the truths demonstrated by Euclid would forever retain their certainty and evidence (Hume, Section II).
Matters of fact, which are the second objects of human reason, are not ascertained in the same manner; nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. That the sun will not rise tomorrow is no less intelligible a proposition, and implies no more contradiction than the affirmation, that it will rise. We should in vain, therefore, attempt to demonstrate its falsehood. Were it demonstratively false, it would imply a contradiction, and could never be distinctly conceived by the mind (Hume, Section IV, Part 1).
This portrayal of human reasoning has become known as Hume's fork. It is an allegory that has been developed by philosophers that depicts David Hume's fundamental distinction between propositions stating or purporting to state the “relations of ideas” and propositions stating or purporting to state “matters of fact and real existence” (Flew, 156). Hume recognizes that with respect to propositions that can be made, that they fall into one of two categories.
It is important here, to define some additional terms that will aid in our understanding of this subject matter before describing the two categories. A priori is something that is knowable before experience (prior = before). A posteriori is something that is knowable after experience (posterior as in behind . . . which is like after). Something that is a posteriori means that in order to determine the true functionality of the proposition it needs to be determined within experience. It requires setting the observer into experience for justification of the claims. A posteriori claims are counter to a priori claims which are independent to experience versus a posteriori claims which are dependent on experience. The truth of the proposition is dependent on experience. Analytic is something found to be true by analyzing the meaning of the concepts involved. Synthetic is found to be true by comparing the statement to the contents of the world (Differences).
So Hume says that there are those propositions that are synthetic propositions. In a synthetic a priori proposition, the predicate is not logically or analytically contained in the subject, i.e., synthetic, and the truth of which is verifiable independently of experience, i.e., a priori. Thus the proposition “Some bodies are heavy” is synthetic because the idea of heaviness is not necessarily contained in that of the bodies. In general, the truth or falsity of synthetic statements is proved only by whether or not they conform to the way the world is and not by virtue of the meaning of the words they contain (Encyclopedia Britannica). Another classic philosophical example of this is ‘the cat is on the mat’. This is a synthetic statement. The validity of the statement can be made by observing it. We can recognize that this statement has true functionality. A proposition has true functionality if it can be verified to be true. So why is this claim true? It’s true from observation or verification. I can see the cat on the mat. It’s true by observation. Hume then talks about an analytic statement which would be the antithesis to the synthetic statement. The classic example is ‘a bachelor is an unmarried man’. Analytic statements have true functionality and are true by definition. The fact that I’m defining an unmarried man means that an unmarried man is also a bachelor. They are interchangeable and mean the same thing either way. Analytic statements are tautological. i.e. A=A. This is known as a tautology. A tautology is a statement that is necessarily true because by virtue of its logical form it cannot be used to make a false assertion (Flew). With respect to the notion of meaning though, tautological statements are essentially meaningless. There isn’t any meaning to be had in a tautological claim (Keterling). Analytic statements still have true functionality, but they really don’t tell us anything. Hume looks at synthetic claims as being more meaningful. They are very rich with data and information. Hume was an empiricist looking to the world for empirical claims that were verifiable and as being the most meaningful as opposed to those of the rationalists.
Analytic sentences are true by definition, and are generally self-explanatory. Additionally, they often have little to no informative value. Examples of analytic sentences include: * Frozen water is ice. * Bachelors are unmarried men. * Two halves make up a whole.
No additional meaning or knowledge is contained in the predicate that is not already given in the subject. Analytic sentences are redundant statements whose clarification relies entirely on definition. They do not give meaningful information about the world. Synthetic statements, on the other hand, are based on our sensory data and experience. The truth-value of a synthetic statements cannot be figured out based solely on logic. If one had had no sensory input from the world, then studying the statement would not yield the meaning of the sentence, as it would for an analytic sentence. Examples of synthetic sentences are: * Children wear hats. * The table in the kitchen is round. * My computer is on.
Synthetic sentences are descriptions of the world that cannot be taken for granted. Sentences that are possibly true but not necessarily true are synthetic.
Going back to the statement ‘the cat is on the mat’ is a synthetic proposition because it required observation in order for the observer to assess its true functionality. In order to assess its true functionality, I had I had to check whether or not the cat was actually on the mat and if the cat is on the mat, then I realize that it is true. It is dependent on experience. All synthetic propositions are a posteriori. In an A priori statement, I don’t have to verify the truth of the claim through experience. It can be verified outside of experience. Going back to the example of the analytic claim that ‘an unmarried man is a bachelor’ I don’t need to go to Bob to verify that he is unmarried and therefore a bachelor. I know by the use of the term bachelor that he is an unmarried man and vice versa that by the use of an unmarried man that he is a bachelor. This is tautological and it doesn’t need to be verified through experience. That’s also what it means to be independent. The truth of it is independent to experience. The converse of that is that all analytic propositions are a priori. They are independent to experience. By the very definition that’s what it means to be independent.
So Hume’s fork shows that all synthetic claims are a posteriori and analytic claims are a priori.
Kant observed that something was missing from all of this. Kant said that a synthetic claim could also be a priori. So that part must be based on experience and the other part of it is independent of experience. It seems like a contradiction. How can both apply? Kant accepted Hume’s analytic/synthetic distinction as the key philosophical tool of analysis. Kant agreed with Hume that all analytic propositions are a priori, and that all a posteriori propositions are synthetic, BUT he disagreed with Hume’s claim that all synthetic propositions are a posteriori and that all a priori propositions are analytic (hence tautological). So, according to Kant, there is such a thing as a SYNTHETIC A PRIORI TRUTH, a meaningful statement about reality whose truth is known independently of observation (Peterson). Kant was trying to develop a compromise between the rationalists and the empiricists. “Thoughts without content are empty, intuitions without concepts are blind.” This statement was meant to grant to the rationalists that sense data alone could not provide knowledge, and to grant to the empiricists that there could be no knowledge in the absence of sensorial contribution (Peterson).
In two of his most famous works, the Critique of Pure Reason and the Prolegomena to any Future Metaphysics, Immanuel Kant tried to resolve the issues of whether and how metaphysics was possible, and by extension, the issue of how synthetic a priori knowledge was possible. Kant says that his purpose in writing the Prolegomena is to get people who think that metaphysics is worth studying to ask themselves whether it is possible at all (Prolegomena, p. 3). And as Kant makes clear later on, he also wishes to present his ideas in a less obscure manner than he did in the Critique of Pure Reason (Prolegomena, p. 9).
Kant's next step is crucial in dealing with the problem of metaphysics. He now takes what he calls the Copernican turn. Like Copernicus, Kant believes that we should not look to what we experience, but rather HOW we experience. Copernicus, in his theory on the apparent motion of the sun, turned away from the accepted belief that the earth revolves around the sun, a belief that seemed to apply to the laws of common sense. Copernicus saw that the movement should not be placed in us, but in something else. His theory was eventually accepted because it had a greater explanatory value than the obvious, common sense statement.
Like Copernicus, Kant felt that we should try to remove ourselves and our influence from the explanation of metaphysics. In other words, he felt that we should look specifically to how we experience things. It was here that Kant turns to his theory of sensibility, or the "form of sensibility" as he calls it (Modern Philosophy, 591). Kant looks not to the exact experience, but rather the act of experiencing. He questions whether we are innately prone to see things in a certain way. Although he concedes that anything we know about the object we are seeing is a posteriori (learned from experience) he goes one step further to assert that the actual act of seeing, how we see, is a form in itself.
This conclusion brought Kant to his next observation that encompasses the consistencies in what we see. Although such descriptive words such as color, shape, or function can change from one person's experience to the next, every experience has both a space and a time. No matter who we are and what lives we lead, everything must have a spatial and temporal origin. Furthermore, Kant also delves into a critique of the Hume cause and effect relationship observation. Unlike Hume, Kant believes that everything must have a cause and an effect. The theory of cause and effect is our attempt to organize and make sense of what is given to us through sensibility (spatially and temporally). It is through this that Kant concludes that general metaphysics is possible.
Here Kant encounters a problem in his theories on metaphysics and the repercussions on his thoughts about sensibility. Spatial and temporal indicators only present the world in terms of human understanding but Kant is aware that there is a world that exists outside of this. He applies matters of faith to believe in things as they are in themselves, but he cannot explain them fully through science. He admits that there is a world that exists independently of our experience, but we also have a need to process things spatially and temporally, so the two cannot exist together (Peterson).
Finally, Kant reaches the conclusion that certain types of metaphysics are possible, while others are not. Transcendental, or general metaphysics is possible if the Copernican turn is applied. Applications of all his theories such as phenomena, spatial, and temporal origins led him to believe that this type of metaphysics, despite what Hume believed, is possible. He admits that transcendent, or special metaphysics is not possible. For us to go beyond our limits of thinking and to get pass spatial and temporal terms is not possible. Essentially, what special metaphysics is asking is to think beyond our limits of thinking, which Kant sees as impossible.
Kant directly deals with the problems presented in Hume's analysis of metaphysics. Where Hume stops his line of thinking and becomes skeptical as to the existence of metaphysics as a science, Kant picks up. He proceeds to analyze both the validity of metaphysics as a science and a force in our lives. Turning to the methods of other credible men in the scientific field such as Copernicus, Kant develops a whole new approach to looking at the world. However, like Hume, Kant encounters an obstacle and does not find a solution for it.

Works Cited
"Difference Between A Priori and A Posteriori."Https://www.reddit.com/r/askphilosophy/. N.p., 12 May 2015. Web. 26 Nov. 2015.
Encyclopedia Britannica Inc., 2015. Web. 30 Nov. 2015
<http://www.britannica.com/topic/synthetic-a-priori-proposition>.
Flew, Antony G. A Dictionary of Philosophy. 2nd ed. New York: St. Martin's, 1984.
Hume, David. An Enquiry Concerning Human Understanding, Harvard Classics Volume 37, n.d. Web. 30 Nov. 2015.
Kant, Immanuel. Critique of Pure Reason, edited by Paul Guyer and Allen W. Wood, Cambridge University Press, 1998
Kant, Immanuel. Prolegomena to Any Future Metaphysics (A revision of the Carus translation with an introduction by Lewis White Beck). The Library of Liberal Arts. Published by Prentice Hall, Inc.: Upper Saddle River, New Jersey 1997
Kemerling, Garth. "Philosophy Pages." Philosophy Pages. 12, 12 Nov. 2011. Web. 26 Nov. 2015.
Peterson, David. "Speedy Lecture: Immanuel Kant (1724 - 1804)." (n.d.): n. pag. Web.