Since our perception is easily deceived, as Plato also argued, true knowledge can not be achieved through perception of the world (experience). Furthermore, according to Descartes, even when perception may be trusted due to not being obscured by distance or other factors one can never be sure that one is not dreaming. “I see so manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep that I am lost in astonishment.” (Descartes, 146) By this skepticism Descartes places a veil between oneself and the world. Everything observed must always be doubted and no true knowledge can be deduced from perception or experience; true knowledge can only be acquired through reason, this is the philosophy of rationalism.
Hume created a philosophy of knowledge in direct opposition to Descartes rationalism. He starts by dividing knowledge into two parts; relations of ideas (geometry, mathematics) and matters of fact. Relations of ideas are principles and ideas that are intuitively or demonstratively certain. Relations of ideas are not really knowledge though, in that they give us no better understanding of the world or philosophy. The second type of knowledge, matters of fact, coming exclusively from cause and effect. “Heat and light are collateral effects of fire, and the one effect may justly be inferred from the other.” (Hume, 26) If one eats a loaf of bread then one can expect to derive nourishment from bread; there is nothing inherent in the observation of a loaf of bread that would tell a person that he would derive nourishment from it. It is only through the experience of having eaten bread that one will find that, indeed, it is nourishing. Hume states: “When we reason a priori, and consider merely any object or cause, as it appears to the mind, independent of all observation, it never could suggest to us the notion of any distinct object, such as its effect much less, show us the inseparable and inviolable connexion between them.” (Hume, 32) The connection between food and nourishment is not self evident, only through experience can it be established.
Hume argues that all knowledge is derived from cause and effect. Furthermore he states; “This proposition that causes and effects are discoverable, not by reason but by experience, will readily be admitted.” (Hume, 27) Where Hume diverges from the common philosophy of his time is in the area of the natural sciences. Many before him considered laws of nature to be a priori knowledge. That an object has weight (gravity) was considered to be true knowledge and a priori knowledge as well. Hume refutes this by pointing out that if one had never observed the interaction of bodies, one would never have assumed that it would fall. If an observer were observing an object from a height, it would be just as likely in that persons mind that the object would go upwards, or downwards, or even sideways. Reason alone would never come to the conclusion that gravity exists without having experienced it.
Where Hume encounters trouble is in predicting the future. Just because all past experience would make one believe that the sun will rise tomorrow, it is just as likely that the sun will not rise. Empiricism is incapable of creating laws; it only states what has always happened in the past. Hume recognizes that people act as if nature does have laws and will continue to act in a predictable manner. He justifies this by custom, the inherent human desire for continuity. We assume that things will always happen in the future the same as they have in the past due to our desire for things to remain the same. Moreover our desire for continuity actually forces us to perceive things as we expect them. “Or in other words; having found in many instances, that any two kinds of objects- flame and heat, snow and cold- have always been conjoined together; if flame or snow be presented anew to the senses, the mind is carried by custom to expect heat or cold, and to believe that such a quality does exist, and will discover itself upon a nearer approach.” (Hume, 49) Rationalism states that all knowledge derives from experience and that our desire for continuity results in “laws of nature” that in fact do not necessarily exist.
There are problems that arise from both rationalism and empiricism. Rationalism creates a world were nothing is knowable except for science and mathematics, and all perception must eternally be doubted. This places an impenetrable boundary between the mind and the world around it. Empiricism allows for us to know the world around us, but never to know what will happen in the future, since we have not experienced in yet. These are both monumental barriers to overcome, but Kant manages to do so.
Kant divides judgments into two categories synthetic and analytic. Synthetic judgment is where new knowledge is derived, whereas analytic merely serves to reduce something into its constituent parts in order to better understand it. An example of synthetic judgment would be fire and heat, since fire produces heat one can use reason to derive the knowledge that fire will always create heat. Therefore new knowledge is created through an observation of nature. This is how a priori knowledge can come about through experience. An example of analytic judgment would be a statement; I am myself, or a=a, all analytic judgments are a priori knowledge, they are self evident.
Kant disagreed with Descartes and philosophers prior to him in his acknowledgment that a priori knowledge in many forms is derived from experience, but disagreed with Hume by stating that it is possible to create laws from empirical data. “All mathematical judgments, without exception, are synthetic.” (Kant, 52) 5+7=12 was considered prior to Kant to be an a priori statement that required no experience to prove. He shows though that merely thinking about the figures 5 and 7 would never result in the sum of 12, rather only through intuition and experience (such as counting fingers), can one arrive at this solution. Therefore this knowledge while yes is a priori, is synthetically created based on experience. Kant goes further by attacking the views of natural science. “Natural science (physics) contains a priori synthetic judgments as principles.” (Kant, 54) Here Kant agrees with Hume that no laws about nature would arise merely from thinking about it. Gravity is only evident when one observes its effects, but he disagrees in not being able to derive natural laws from this experience. Kant fixes the problem Hume created of not being able to derive laws from experience by using synthetic judgment.
Kant actually directly addresses Hume’s argument that nature does not obey laws only appears to due to our desire for continuity.
He occupied himself exclusively with the synthetic proposition regarding the connection of an effect with its cause (principium causalitatis), and he believed himself to have shown that such an a priori proposition is entirely impossible. If we accept his conclusions, then all that we call metaphysics is a mere delusion whereby we fancy ourselves to have rational insight into what, in actual fact, is borrowed solely from experience, and under the influence of custom has taken the illusory semblance of necessity. (Kant, 55)
He basically states that the conclusion that nature obeys no laws is ridiculous, in that it cripples our ability to predict the future, and makes virtually everything unknowable.
The role of experience in knowledge is a never question that really can not be answered. Kant created a theory of knowledge that allows for new a priori knowledge to be created from rational interpretations of experience, but exist independently of it. His epistemology solves the problem of predicting future outcomes that Hume is stuck in, and allows for new knowledge to be created from experience; an area where Descartes is lacking. Kant provides a working day to day way of viewing the world that fits all the purposes of mankind. His only fault is in being unable to prove Descartes wrong; for while Kant’s theories are far more workable and useful than any others, he is still unable answer Descartes’ skepticism. We all could be dreaming, or brains in vats, and if that is true than experience is indeed unable to create true knowledge. I for one choose to believe that my perception is accurate, and if I am wrong it really doesn’t matter anyway because I will never know the difference.
Works Cited
Haldane and Ross. The Philosophical Works of Descartes, Volume 1. pgs. 132-199
Hume, David. An Enquiry concerning Human Understanding and A Treatise of Human Nature. Pgs. 24-41, 42-59, 60-63.
Kant, Immanuel. Critiques of Pure Reason. Pgs 41-62
