David Hume, as Bertrand Russell suggests in the History of Western Philosophy, represents a kind of ‘dead end’ in a certain avenue of philosophical skepticism. Russell argues that it is impossible to go further in Hume’s direction and one can only hope for a relatively less skeptical construct.
Hume’s proposition adds considerably to the complexity of the problem while breaking it into two dimensional fractures. Namely metaphysical, which is rationalism and epistemological, which is empiricism.
A large part of 17th and 18th centuries saw notable philosophers struggling with this intriguing problem. It was Immanuel Kant, who for the first time, tried to reduce both these fractures to some extent. Nature of the world, according to Kantian construct, can be appreciated as a duality at two levels; namely noumenon (as it is) and phenomenon (as it appears to be). The causality, how we perceive it, only reigns in the world as it appears to us and cannot be conceived in the domain where things exist as they are. Human mind, as it cannot go beyond the phenomenal world, has no option but to concede to this cause-effect duo. We always need to beg causes in order to have a coherent experience. However, knowledge, even though based on this experience, is not derived from it.
Contrary to rationalists, we cannot explain the world without resorting to causality; contrary to empiricist, we must not derive the knowledge of noumena from experience.
Kant’s solution, though seemingly plausible, can be deemed problematic as far as application of Hume’s initial proposition to scientific episteme is concerned. Science’s claim, as I have already contended, is to yield knowledge (i.e. explain and predict) and if it is only concerned with the world as it appear to us, its claim is not justified. At maximum, it can claim to be descriptive; for it is through science that we can describe the phenomenon of sun rise but cannot reasonably justify the contention that sun will surely rise tomorrow. It is due to scientific certainty that we do not have any qualms in stating that ‘water gives life to plants’, but reason alone cannot be the basis of our expectation that water would keep on doing so in future.
What then are the bases for unflagging beliefs like these?
Excluding psychological and social domains, as I restrict myself to science, most contemporary solutions to the problem of causation put forth alternatives, which stem from the induction and probability theories. Bertrand Russell brilliantly posits his views on induction in the Problems of Philosophy. He writes:
The question we really have to ask is: ‘When two things have been found to be often associated, and no instance is known of the one occurring without the other, does the occurrence of one of the two, in a fresh instance, give any good ground for expecting the other?’ On our answer to this question must depend the validity of the whole of our expectations as to the future, the whole of the results obtained by induction, and in fact practically all the beliefs upon which our daily life is based.[…] The principle we are examining may be called the principle of induction, and its two parts may be stated as follows:
(a) When a thing of a certain sort A has been found to be associated with a thing of a certain other sort B, and has never been found dissociated from a thing of the sort B, the greater the number of cases in which A and B have been associated, the greater is the probability that they will be associated in a fresh case in which one of them is known to be present;
(b) Under the same circumstances, a sufficient number of cases of association will make the probability of a fresh association nearly a certainty, and will make it approach certainty without limit.
It is pretty obvious that Russell is trying here to circumvent Hume’s dilemma rather than resolving it. Inductive inference, as it is obvious from the above articulation, does not claim to bring about true conclusions from true premises; rather its objective is to yield probable conclusions from true premises. Hume’s argument, on the other hand, established two things beyond doubt; one, that it is impossible to prove that any inductive inference with true premises will have a true conclusion and two, that every inductive inference in future with true premises may yield a false conclusion.
The initial question therefore pops up in a new garb: Is it rational to accept an inductive inference?
to be continued…