Notes on epistemology
Two kinds of objects occupy our minds: relations of ideas and matters of fact. The former are propositions that can be arrived at by the mere use of the intellect (mathematical formulas for instance), through the application of the principle of non contradiction. The latter cannot be derived in the same way because the opposite of any matter of fact is always possible, for instance, that the sun will rise tomorrow does not imply a logical necessity, it is something we infer because of habit.*
On custom and habit.We infer, infer, infer. Habit allows us to exit the realm of experience and immediacy. But any proposition concerning the future has no other foundation than habit. Contiguity and succession of events to not imply any necessary connections. Customs create beliefs. What is belief? 'Belief distinguishes ideas of judgement from fictions of the imagination and is something felt by the mind'. Hume claims that belief is a more intense conception than what attends the fictions of the imagination, reinforced by objects and memories. Here note that belief is a feeling, and Hume moves from the logico-rational explanation (objective) to an emotive-rational explanation (subjective). Imagination and memory, together with experience, are the foundations of knowledge. He negates the ontological and substantial value of the principle of cause and effect, thus questioning the whole foundations of metaphysics. 'We have no other notion of cause and effect, but that of certain objects, which have been always conjoin'd [sic] together, and which in all past instances have been found inseparable. We cannot penetrate into the reason of the conjunction. We only observe the thing itself, and always find that from the constant conjunction the objects acquire an union in the imagination.' - David Hume, A Treatise of Human Nature (1740). To this he opposes his theory of passions, to which reason is subservient. Hume is a moderate sceptic in so far as he believed that we ought to limit out research to the limited fields that human understanding can investigate. These constitute the knowledge of relations between ideas (maths). All matters of fact can only be ascertained by experience, they cannot be demonstrated (nor predicted). He was a great influence on Immanuel Kant.