Nicolas Malebranche
He was a philosophical rival of Hume. Malebranche was a Catholic priest, and his ideas about thought and experience were based upon his religious convictions. His premise was that every cause is a manifestation of the predestination of God. In his section "Of the idea of necessary connection (in two parts)," Hume rejects Malebranche's conclusion. Instead, Hume proposes, that causes are seen as the conjunction of repeated impressions.
Queen Elizabeth
The Queen of England who reigned during Hume's day makes an appearance in his book. He uses her to illustrate an example of just how reliable or unreliable witnesses must be considered. If all historians said Queen Elizabeth was witness to be alive and well after her funeral, then people must conclude that she had been raised back to life from death. Hume argues that, despite the supposed reliability of the historians due to their credibility and numbers, an intelligent man must question this report because it violates the natural laws.
The Friend
In his section "Of a particular providence and of a future state" Hume writes about a supposed argument made by his friend. The friend remains unnamed. Use of a third party to present certain difficult conclusions is common among philosophers because it allows them to remain outside of the argument and pose questions to the orator. In fact, Hume does this very thing at the end of his friend's discussion of providence. His friend presents his own argument through an additional party, a speech by Epicurus.
Epicurus
He is an ancient Greek philosopher. Hume's friend uses an imaginary speech by Epicurus to discuss his own views on the topic of providence. In this context, then, Hume is using three layers of ownership to distance himself from the actual arguments being made: himself as a witness, his friend as the speaker, and Epicurus as the fictional orator. The basic argument which his friend makes and credits (falsely) to Epicurus, is that effects can be accredited to specific causes but that the process cannot be reversed to use causes to predict effects.
Rene Descartes
Hume addresses Descartes' views upon epistemology in his section entitled "Of the academical or skeptical philosophy (in three parts)." He disagrees with Descartes conclusions, insisting that skepticism is a logical but extremely destructive pattern of thought which can be broken. Descartes was a French philosopher of the 17th century who is regarded as the Father of Modern Western Philosophy.
John Locke
Hume refutes Locke's view of epistemology in his section "Of the academical or skeptical philosophy (in three parts)." Locke was a 17th century philosopher from England. He is considered the Father of Liberalism and was a major figure during the Enlightenment. While Human believes in epistemology based upon experience, Locke proposes knowledge through consciousness.
