On An Enquiry Concerning Human Understanding, Section V by David Hume

Suppose a person, though endowed with the strongest faculties of reason and reflection, to be brought on a sudden into this world; he would, indeed, immediately observe a continual succession of objects, and one event following another; but he would not be able to discover anything farther. He would not, at first, by any reasoning, be able to reach the idea of cause and effect; since the particular powers, by which all natural operations are performed, never appear to the senses; nor is it reasonable to conclude, merely because one event, in one instance, precedes another, that therefore the one is the cause, the other the effect. Their conjunction may be arbitrary and casual. There may be no reason to infer the existence of one from the appearance of the other. And in a word, such a person, without more experience, could never employ his conjecture or reasoning concerning any matter of fact, or be assured of anything beyond what was immediately present to his memory and senses.

-David Hume, from An Enquiry Concerning Human Understanding, Section V

In this passage, Hume formulates the problem of induction by arguing that there is no deductive justification for inductive reasoning, or holding any belief about the unobserved after assuming a regularity holds generally because said regularity holds in experience. Hume provides the example of a person capable of memory and reasoning suddenly coming into existence, contending that although this person would surely observe events happening in succession, he cannot deductively reach any cause and effect relationships between observed events. The fundamental powers which propel nature cannot be directly observed, thus it would be unreasonable to conclude any particular event is the cause of another. Consequently, a logical person has no reason to assume the qualities of something because of the appearance of another and cannot be sure of anything that is not immediately perceived by senses.

Hume’s own skeptical solution arrives at the conclusion that there is no justification for induction, later claiming that inferences from experience are the result of an instinctual “Custom,” a natural propensity to expect an event after experiencing repetition of said event, not of reasoning.

Strawson rejects the problem completely by pinpointing two blunders in Hume’s argument. The first flaw is the supposition that induction relies on an assumption that the future will resemble the past. This is a troublesome assumption since that the future will resemble the past does not apply universally to all inductive reasoning, instead we project regularity selectively. Another point of contention is that induction need not be justified in the first place. The problem of induction arises when we attempt to deductively justify inductive thinking; however, there is no sense in justifying induction because induction is paradigm case of rational inference. Hume’s problem is thusly dissolved.

The first claim doesn’t reject Hume’s problem because an explanation of how we selectively project regularities is not needed to question whether induction is justifiable. Hume’s induction relies on the belief that a certain regularity will hold, not that all past regularities will hold. If we just focus on cases of “good inductive reasoning,” and ignore cases in which we don’t project regularities, the question of whether good inductive reasoning is justifiable remains. For example, we can question why we can assume a rock hit the ground after release because rocks have always fallen without needing to explain why we don’t believe humans will never reach Mars just because humans have never previously reached Mars.

The second point claims that if induction is a paradigm case of rationality, then Hume’s question of is induction justifiable falls apart, similar to how questioning the legality of a law is inane because legality is defined through laws. Assuming that induction were a paradigm case of rationality, which remains debatable, Hume’s question is rendered circular or trivial, but then the discussion transitions to a new, normative question: should we use induction? Different rationalities can be defined by an infinite variety of different types of reasoning, and the question of whether we should use our inherent induction-based rationality arises.