This chapter contains the text of two radio talks for the Free Radio-University, Berlin, delivered in the late 1950s. These were prepared while Popper was working on The Postscript to The Logic of Scientific Discovery: After 25 Years, which was to appear shortly after The Logic of Scientific Discovery (1959). The 25 years referred to the period from 1934 (when the German version of the book was published) to 1959. When the postscript eventually appeared after fifty years it contained a fascinating epilogue on metaphysical research programs which was substantially written in the 1950s. This topic was briefly mentioned in his autobiography for the Schillp volume (published separately as Unended Quest) and it clearly signals his radical departure from the anti-metaphysical positivism of the Vienna Circle.
Part 1. Kant and the logic of experience.
This section contains a passage that Bryan Magee identified as the key to "locating" Popper in relation to the western tradition (that was in the chapter on Popper in Magee's Confessions of a Philosopher). Magee regards him as a reconstructed Kantian and this passage brings that out rather well, as Popper agreed although that was not the original purpose of the text.
"In order to solve the riddle of experience, and to explain how natural science and experience are at all possible, Kant constructed his theory of experience and of natural science. I admire this theory as a truly heroic attempt to solve the paradox of experience, yet I believe that it answers a false question and hence that it is in part irrelevant. Kant, the great discoverer of the riddle of experience, was in error about one important point..."
"What was this error? As I have said, Kant, like almost all philosophers and epistemologists right into the twentieth century, was convinced that Newton's theory was true... before Einstein."
"Even those who do not accept Einstein's theory of gravitation ought to accept that his was an achievement of truly epoch-making significance. For his theory established at least that Newton's theory, no matter whether true or false, was certainly not the only possible system of celestial mechanics that could explain the phenomena in a simple and convincing way..."
"Now if, unlike Kant, we consider Newton's theory as a hypothesis whose truth is problematic, then we must radically alter Kant's problem. No wonder that his solution no longer suits the new post-Einsteinean formulation of the problem, and that it must be amended accordingly."
"Kant's solution to the problem is well known. He assumed, correctly I think, that the world as we know it is our interpretation of the observable facts in the light of theories that we ourselves invent. As Kant puts it: 'Our intellect does not draw its laws from nature... but imposes them upon nature.' While I regard this formulation of Kant's as essentially correct, I feel that it is a little too radical, and I should therefore like to put it in the following modified form: 'Our intellect does not draw its laws from nature, but tries -- with varying degrees of success -- to impose upon nature laws which it freely invents.'..."
"We invent our myths and our theories and we try them out: we try to see how far they take us. And we improve our theories if we can. The better theory is the one that has the greater explanatory power; that explains more; that explains with greater precision; and that allows us to make better predictions."
"Since Kant believed that it was our task to explain the uniqueness and the truth of Newton's theory, he was led to the belief that this theory followed inescapably and with logical necessity from the laws of our understanding. The modification of Kant's solution which I propose, in accordance with the Einsteinian revolution, frees us from this compulsion. In this way, theories are seen to be the free creations of our own minds, the result of an almost poetic intuition, of an attempt to understand intuitively the laws of nature. But we no longer try to force our creations upon nature. On the contrary, we question nature, as Kant taught us to do, and we try to elicit from her negative answers concerning the truth of our theories: we do not try to prove or to verify them, but we test them by trying to disprove or falsify them, to refute them."
"In this way the freedom and boldness of our theoretical creations can be controlled and tempered by self-criticism, and by the severest tests we can design. It is here, through our critical methods of testing, that scientific rigor and logic enter into empirical science."
Part 2. The problem of the irrefutability of philosophical theories.
Somewhere in Popper's writing prior to this time there is a passage where he stated that early in his career he considered that the domain of rational discussion was limited to "scientific" matters. Certainly he had given up that view by the time he wrote The Open Society and quite likely by the time he finished Logic der Forschung because that contains rational discussion of principles of method which cannot be empirically tested.
In this section of the paper he demonstrated how philosophical doctrines can be subjected to criticism even though they cannot be refuted by facts. He nominated a number of philosophical theories, all of which he considers to be false.
First, determinism: the future is contained in the present, inasmuch as it is fully determined by the present.
Second, idealism: the world is my dream.
Third, irrationalism: we have irrational or supra-rational experiences in which we experience ourselves as things-in-themselves; and so we have some kind of knowledge of things-in-themselves.
Fourth, voluntarism: in our own volitions we know ourselves as wills. The thing-in-itself is the will.
Fifth, nihilism: in our boredom we know ourselves as nothings. The thing-in-itsself is Nothingness.
After some discussion of the logic of testing and refutation, he approached his problem: If all philosophical theories are irrefutable, how can we distinguish between true and false philosophical theories? He then specified three types of theory.
Logical and mathematical theories.
Empirical (scientific) theories.
Philosophical or mataphysical theories.
Theories of type 1 are tested by attempted refutation, especally by finding internal contradictions. Decisions in these cases are usually final.
Scientific theories are similarly tested by the process of criticism and in this case observations can fit into the critical discussion.
For the third kind of problems, he proposed a solution that is based on a situational analysis to asses the adequacy of the theory as a solution to a problem. Actually he didn't use the term situational analysis but that is an important concept that will come in useful anytime we are contemplating the reasons for human actions or the rationality/adequacy of human decisons.
"My solution is this: if a philosophical theory were no more than an isolated assertion about the world, flung at us with an implied 'take it or leave it' and without a hint of any connection with anything else, then indeed it would be beyond discussion. But the same might be said of an empirical theory... A theory is comprehensible and reasonable only in its relation to a given problem-situation, and it can be rationally discussed only by discussing this relation."
The critical approach in its widest ramifications can then be said to involve five kinds of criticsm:
The check on the problem.
The check of internal consistency.
The check of consistency with other well-tested theories.
The check of evidence -- observation and experiment.
The check on the metaphysics.