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Karl Popper’s Solution to the Problem of Induction and Hume’s Problem.

The Minimalist Conception of Rationality

by Dmytro Sepetyi

Zaporizhzhya State Medical University, Ukraine

[email protected]


Onĺ of the most important achievements, if not the most important achievement, on which Karl Popper prided himself was his solution to the problem of induction or Hume’s problem. These two names, ‘the problem of induction’ and ‘Hume’s problem’, are used as synonymous by Popper and other participants of the discussion. I suspect that this may be misleading for understanding of Popper’s solution or, rather, solutions. Really, Hume’s problem seems to be the problem of the justification of induction, but there is more to it: it is the problem of the justification of induction, as well as the problem of the justification of any possible alternative with which induction may be replaced. Popper’s solution to the problem of induction is hypothetico-deductivism and falsificationism. Popper’s solution to the problem of justification – now of hypothetico-deductivism and falsificationism instead of induction – is his critical, non-justificationist, minimalist conception of rationality – critical rationalism.


The more specific problem of induction can be formulated as follows: given that we obtain our general theories by inductive generalization from experience, what must be the inductive procedure, inductive method, inductive logics to demonstrate the truth or, at least, high probability of our theories? Popper’s solution to this problem is:

1)     there is no inductive logics, no correct inductive procedure, no way to demonstrate the truth or, at least, high probability of our theories;

2)     the “given” – the theory that we obtain our general theories by inductive generalization from experience – is mistaken. In fact, we obtain our theories as conjectures made in attempts to solve our problems; after this, we should expose these hypotheses (tentative solutions to our problems) to critical discussion and empirical testing, which are attempts to refute, falsify the theory at issue by demonstrating that its predictions contradict with the results of properly made reproducible (usually, experimental) observations; hypotheses that stand these ordeals are to be tentatively accepted as true. (The normative component, expressed by ‘should’ and ‘are to be’, defines favorable conditions for the development of our knowledge, the major factor of the progress in science.)

Though some of Popper’s critics say that his hypothetico-deductive falsificationist theory is in fact a variety of induction, there is very little in common, as we can see from the schemes below, which represent the structure of cognitive process according with the theory of induction and according with Popper’s theory.

Inductivist theory:

Popper’s theory:


Now we turn to the more general problem – Hume’s problem of the justification of induction, or of whatever we put in the place of induction. Hume contended that it is impossible to properly rationally justify induction; hence our reliance on it is irrational. Here, ‘proper rational justification’ can be defined as a logically valid argument without unjustified premises. We obtain a proper rational justification if and only if the argument is logically valid and all its premises are justified. If (some of) the premises aren’t justified, then the conclusion drawn from them is just as unjustified. But such a proper rational justification is obviously impossible! It either involves us into infinite regress or closes us into a vicious logical circle. And this argument hits not only induction but any contender for its place in our general account of how we obtain and develop our theoretical knowledge!

Popper’s solution to this problem is ‘biting the bullet’. Yes, it is impossible to justify, in the way demanded, anything whatever (including, surely, hypothetico-deductivism and falsificationism). But, in the one very important meaning of the word ‘rationality’, this doesn’t mean that it is impossible to be rational (it is inevitable to be irrational) with respect to all, or most, or some our ideas. This meaning – which I will call critical or minimalist or non-justificationist conception of rationality – is that we admit that we may be mistaken in our views, and we keep our views open to critical discussion and are willing to renounce or revise them if some arguments to this end happen to be convincing for us. As far as the content of the notion of rationality is concerned, this is all that can be defended and retained after Hume’s attack. And this is all that needs to be defended and retained.

Popper’s philosophy as a whole can be considered as thorough thinking through the consequences of this conception of rationality. His critical rationalism is the faith in critical discussion as the way to improve our knowledge, as well as to achieve political solutions (whether as a matter of agreement or of compromise), in the force of argument as opposed to violence (which inevitably follows the disdain of arguments).


Written November 26, 2013

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