The diverseness of these writers shows what they gleaned from reading Hume; it reflects not only the richness of their sources but also the wide range of Hume's empiricism. Contemporary philosophers recognize Hume as one of the most thoroughgoing exponents of philosophical naturalism.
David Hume sought to develop more fully the consequences of Locke's cautious empiricism by applying the scientific methods of observation to a study of human nature itself. He was of the opinion that we cannot rely on the common-sense pronouncements of popular superstition, which illustrate human conduct without offering any illumination, nor can we achieve any genuine progress by means of abstract metaphysical speculation, which imposes a spurious clarity upon profound issues- that we are entirely unjustified in thinking that we can ever know anything about matters of fact. He thought that the alternative is to reject all easy answers; employing the negative results of philosophical skepticism as a legitimate place to start.
Hume felt that since human beings live and function in the world, we should try to observe how they do so. The key principle to be applied to any investigation of our cognitive capacities is, then, an attempt to discover the causes of human belief. According to Hume, the proper goal of philosophy is simply to explain why we believe what we do. His own attempt to achieve that goal was the focus of Book I of his book, the Treatise of Human Nature and all of the first Enquiry.
. He defines these terms thus in his An Enquiry Concerning Human Understanding: "By the term impression, then, I mean all our more lively perceptions, when we hear, or see, or feel, or love, or hate, or desire, or will. And impressions are distinguished from ideas, which are the less lively perceptions, of which we are conscious, when we reflect on any of those sensations or movements above mentioned." He further specifies ideas, saying, "It seems a proposition, which will not admit of much dispute, that all our ideas are nothing but copies of our impressions, or, in other words, that it is impossible for us to think of anything, which we have not antecedently felt, either by our external or internal senses." This forms an important aspect of Hume's skepticism, for he says that we cannot be certain a thing, such as God, a soul, or a self, exists unless we can point out the impression from which the idea of the thing is derived.
Hume's analysis of human belief begins with a careful distinction among our mental contents: impressions, which are the direct, vivid, and forceful products of immediate experience; ideas are merely feeble copies of these original impressions. (Enquiry II) for example, the color of the ink on which this script is printed is an impression, while the memory of the color of my former car is merely an idea. Hume assumed every idea must be derived from an antecedent impression, thus it always makes sense to inquire into the origins of our ideas by asking from which impressions they are derived.
Hume went further in Enquiry IV i to distinguished between two sorts of belief. Relations of ideas are beliefs grounded wholly on associations formed within the mind; they are capable of demonstration because they have no external referent. Matters of fact are beliefs