The new era of philosophy rose against the background of the great social changes. The new theories and discoveries in the scientific field had a great impact on the development of all spheres of life. Philosophy was not an exception. One of the greatest philosophers of those days René Descartes offered a revolutionary new perspective on the subject. In his work Meditations on First Philosophy, Descartes built knowledge on a new foundation, based on the strategy of defeating skepticism on its own ground. This strategy is known as the method of doubt.
The Meditations on First Philosophy consists of six parts (Meditations), where the philosopher broke all knowledge by doubting, down to the elementary pieces of knowledge that are impossible to doubt. His masterpiece of philosophy starts with doubts about the information he gets with all senses because they could be false, as an illusion or a dream. Descartes doubts the existence of God because he could be deceived by his teachers. Furthermore, the philosopher even doubts arithmetical and geometrical fundamental knowledge. He explains this doubt by the possibility of being deceived by an “evil genius.” René Descartes casts doubt on the world that exists outside his thinking, as it could be only a dream, created by a demon. Eventually, the philosopher even doubts the reality of his own body. Thus, Descartes sweeps all his beliefs and knowledge to rebuild it again based on undoubted fact. According to René Descartes, the only absolute truth that is impossible to doubt is his own existence.
Descartes states that his own existence is undoubtful because he is thinking. He sees himself as a thinking being. However, he questions whether his body exists the way he sees it, or it is a result of being deceived by a demon. Thus, the philosopher takes his existence as a thinking being as a start point of rebuilding the foundation of all knowledge. He offers the theory of ideas. According to this theory, ideas are the result of thinking, and they can be generated by the only three possible sources. The first source is the outside world (adventitious), the second is the mind (factitious), and the last source is God (innate). However, that does not prove the existence of the outside world, and as it is possible to imagine anything, everything depends on the existence of God. Therefore, after Descartes proved his own existence the next step the philosopher takes is proving the existence of God. He uses for this purpose the cosmological and the ontological arguments. According to these arguments, the source of the idea about God can be neither adventitious, nor factitious, but can only come from God because any idea must bear as much reality as the content of the idea itself. The idea about God’s existence has unlimited content; hence, the source of this idea is infinite, which is God. Therefore, God exists. He confirms this argument with pointing out his own imperfection. In other words, Descartes states that he could not cause himself. Despite the fact, his appearance in this world was caused by his parents, the chain of causes must have an end. Thus, the original cause of everybody is self-caused being, which is God.
These two proofs of existence have led Descartes to the conclusion that people cannot be deceived about their existence and the material world around them. He states that people can be deceived, however, everything that people comprehend have to be true because of the existence of a perfect, merciful God, who does not let people be deceived so much. Thus, from Descartes’ point of view, people are created with an ability to comprehend a thing when they are clearly aware of it, understand its nature and qualities by which a thing can be differentiated from others. As a result, if people can clearly comprehend the trustworthiness of mathematics, an external world, and the existence of their bodies they can be sure that all this things as real as they look. According to Descartes, knowledge forms an inferential system that is based on undoubtful axioms, which are the foundation of the truths of the sciences.
John Locke is a famous philosopher, who took over a number of ideas from Descartes. However, he disagrees with Descartes’ separation between knowledge and experience. Unlike Descartes, Locke claims that sensations and reflections are the only sources of knowledge. According to this philosopher, the mind is a blank slate, and any experience leaves a mark on it. Thus, people are not born with any ideas but get them from the experience. All ideas are representative of subjects as they really are. Nevertheless, he draws the line between physical objects and the way people see things. Locke explains it by the fact that things have primary and secondary qualities. Primary qualities such as weight, size, and shape are possible to measure, and secondary qualities, such as smell and color, cause certain sensations and they cannot be measured. According to Locke, humans’ ideas are the copies of physical objects.
Comparing Descartes to Locke, it is possible to see that the Descartes’ rationalist account of knowledge of external objects cannot withstand criticisms of Locke’s empiricism. According to Locke, it is impossible to get any knowledge of the surrounding world by sitting and thinking, while Descartes states it is possible. If to take as an example the taste of a lemon, one could never come up with an idea that it is sour without tasting it. Moreover, thinking by itself requires such knowledge as language or associations that come from hearing, seeing, and observing the surrounding world. Thus, Descartes’ statement that thinking proves the existence can be disputed because, for instance, newborn babies cannot think yet; however, they exist and can sense. Furthermore, in contrast to Locke, Descartes based his philosophy on the proof of God’s existence. Thus, if one finds any faults in this prove the whole structure of the philosophy will be destroyed. These arguments make Locke’s empiricist account more plausible.
The Problems of Induction
David Hume was the first empiricist philosopher, who proposed the usage of a term “the problem of induction.” In his works, the philosopher modified Locke’s empiricism by stating that perceptions have two forms, which are impressions and ideas. From Hume’s point of view, these two forms are mental events, and the only difference between them lies in the extent of their vividness. The philosopher states that impressions, which are considered the original perceptions, are more vivid than ideas. Moreover, he claims that any idea is a weakened impression. According to Hume, imagination generates new ideas that have no direct connection with sense experience, by integrating simple ideas.
David Hume formulated two problems of the induction. The first one is the logical problem. Referring to this problem, the philosopher raises the question whether people can rationally justify their inferences based on previous experiences. Hume argues that human opinion with regard to what was not observed have no justification. The second problem of the induction is psychological. Regarding this problem, He asks about the reason why people believe and expect that experiences that they had in the past are connected to the unobserved experiences. In other words, he is looking for an explanation of the reason why people are so sure in their expectations. The philosopher explains it by creating a habit. He claims that if people find out that some events are connected to each other, the human mind will assume by the inductive belief-generating mechanism that one causes another.
The problems of induction are problematic for the empiricist accounts of knowledge. From Hume’s perspective, the induction’s principle is not the result of inductive reasoning. According to the empiricist accounts of knowledge, the foundation of knowledge about the real world is based on senses. Thus, experience plays a predominant role in the accumulation of knowledge, which is contrary to the Hume’s theory described above. This contradiction can be considered a serious problem not only from an empiricist point of view but also from the perspective of common sense. David Hume states that every link with the reality is purely based on an accident. He says that even if the premise of a prognostic inductive inference is true, the deduction might be false. Such statements create problems of common beliefs about how the surrounding world functions. Therefore, all kinds of knowledge have no foundation, which makes people trust in science and its methods unreliable. Scientists would not be able to move forward in their discoveries without having the results of their past experiences as a base.
In accordance with Hume’s problems of induction, the formation of habits is controlled by the expectations. In order for any impression to be repeated people should define it as a replication of the previous events. However, expectations define what will count as a repetition of a previous event. Consequently, expectations are not the result of repetitions of experience. Inversely, they precede experience. Thus, Hume’s explanation of expectations cannot be applied to such facts, as the sun will rise tomorrow.
Summarizing Hume’s theory, it is possible to say that if people could not predict the future outcomes of their actions by relying on the previous experiences, the world would be in chaos. Certainly, the theory of probability and various possible circumstances must be taken into consideration when one makes a prediction. However, it does not mean that people cannot learn from the past.