An Enquiry Concerning Human Understanding Background David Hume published An Enquiry Concerning Human Understanding in 1748. He was a respected empiricist philosopher, meaning he believed that all thought is based upon experience. Credited with founding the rational processes of cognitive science, Hume holds a prominent place among the great philosophers. Although he rejected many of the ideas of his predecessors - including Descartes, Darwin, and Locke - he was hugely influential in the ideas of many successive generations of philosophers. In fact, Immanuel Kant credits his pursuit of philosophy to Hume's work.
Hume wrote An Enquiry as a follow-up to his first book A Treatise of Human Nature. A Treatise was poorly received upon its publishing, much to Hume's disappointment. Consequently, in An Enquiry Hume presented the same conclusions but in more direct terms, having removed some sections and simplified his arguments. He thought perhaps people didn't appreciate his first book simply because they didn't possess the patience to read it thoroughly. Apparently, he did something right because An Enquiry has been widely accepted and revered ever since it was first published.
An Enquiry is Hume's attempt to explain thought. He was an epistemologist, so he was concerned with describing what can be known and the processes by which it is known. In this book, he first dedicates a section to explaining how he defines epistemology. Then he logically orders his arguments in sections which progress and compound to create a complete picture of human experience.
He differentiates between relations of ideas and fact. Impressions are experiences that we get through our five senses, i.e., sense of touch, taste, smell, sight and sound. Ideas are notions related to these impressions. Mostly, relations of ideas are conceptual truths, so their negation results in contradiction. Facts are common truths that we get from sensory experience. Negation of fact is not contradictory.
He further suggests habit enforces an observation of necessary relation between events. Our references about fact are based on probability. Suppose that experience teaches that two events are conjoined, the mind infers a causal link between them.
Hume argues that all meaningful terms must be reducible to the simple impressions from which they are built. There is no simple impression of cause and effect, hence they appear meaningless. He turns these conclusions to the view of free will and determinism. If we do not see any relation between events, then we do not worry that our actions are predetermined. We view free will as the freedom to act according to our will.
At the end of the enquiry, he argues that human and animal reasons are similar. He further says impulsive beliefs formed by tradition help us to succeed in the world, and we should reject abstract and metaphysical speculations as absurd and unnecessary.