Uncertainty Problems In Modern Philosophy

In the history of the western philosophy,the philosopher who first used "Certainty" as a philosophical concept is Descartes.And then the problem of certainty became a very important problem in the epistemology.This article is going to discuss the problem of certainty from two aspects:1,the certainty of external world;2,the certainty of knowledge.The former comes from the skepticism of Descartes,Berkeley and Hume, which claims that the existence of external world is inferred from our perceptions, thus its existence is doubtful.This claim not only relates to the existence of external world,but also relates to our knowledge of external world.The latter comes from Descartes' attempt to establish the Knowledge Tree.Descartes used the concept "Certainty" to discuss the problem of knowledge,and tried to make distinctions between different kinds of knowledge.Philosophers after Descartes,like Locke, Spinoza,Leibniz and Hume,usually divided our knowledge into knowledge of sense, knowledge of reason and knowledge of intuition,according to different degrees of certainty.This article is going to discuss the correlative theory of Descartes,Hume and Kant from the angle of "certainty".And the starting point is Descartes' doubt of the external sense,namely,doubt of the existence of external world,which was further elaborated in the theory of Berkeley and Hume.Kant named this skepticism as "the fourth paralogism of transcendental psychology".And he critiqued this skepticism through distinguishing phenomena from thing-in-itself,by which he affirmed not only the reality of phenomena,but also the existence of thing-in-itself.Actually speaking,certainty is not only a problem referring to rationalistic area,but also referring to practical area,namely,the problem of belief and moral,which was absolutely the main point in the theory of Descartes and Kant.Thus,the practical area should be another aspect of the problem of certainty.