The Question of Certainty
We are living in a world where there are various theories, views and opinions about many different issues. These theories, views and opinions are changing, as everyday new scientific discoveries are made and new theories conducted. Consequently, our knowledge and what we know for certain, or in other words what we think that we know for certain today might change tomorrow. This raises the question whether there is anything certain and what we can know with certainty. Some philosophers have searched for the answer of this question. Descartes and Hume are among them who are concerned with the problem of certainty. Both Descartes and Hume have tried to find a basis for certain knowledge. However, they differ from each other in their point of view on the foundation of this certain knowledge.
Descartes’ aim is to find out a system of thought, which will be the foundation of the principles of absolute certainty. Descartes starts with rejecting any idea as certain and he tries to discover the basis of certainty. Descartes uses the method of doubting in order to find principles, which cannot be doubted. He starts doubting every item of knowledge he previously believed in order to arrive at certain knowledge
Moreover, Hume makes a distinction between relations of ideas and matters of fact. He divides his ideas into three categories: innate, adventitious, and factitious. Accordingly, he believes that ideas are effects and their causes should be found out. He investigates his different ideas and he discovers that his ideas differ from each other in their content and cause. Then, Hume questions how we know the principle of cause and effect. For example, the square of the hypotenuse is equal to the sum of the squares of the two sides and denial of these mathematical truths would result in a contradiction. This means our sense perception about wax changes, however it is still called wax because our reason tells us that it is still the same wax. As a result of doubting, Descartes finds out that our senses can deceive us and they are not reliable because they can be imaginary, illusionary and deceptive. For Hume, these ideas are true by definition. Descartes argues that things that are certain appear in his mind clearly and distinctly. Consequently, Descartes concludes that certain knowledge contains clarity and distinctness. In fact, there is not any logical contradiction in stating that the sun will not rise tomorrow. On the other hand, Hume believes this idea is wrong because he thinks cause and effect arises from past experience. Hume considers cause and effect as the most important element in knowledge.