Carnap was driven from Germany by Hitler, and his position has been condemned in the Soviet Union as 'subjective idealism*. Even in the United States, there have been a great many who could not understand this attempt to turn philosophy into a scientific discipline with substantive scientific results, and who have been led to extreme and absurd misinterpretations of the work I have been reporting to you here. Few, perhaps, would have expected traditional empiricism to lead to the development of a speculative theory of ' universal learning machines'; and yet, in retrospect, a concern with systematizing inductive logic has been the oldest concern of empiricist philosophers from Bacon on. No one can yet predict the outcome of this speculative scientific venture. But it is amply clear, whether this particular venture succeeds or fails, that the toleration of philosophical and scientific speculation brings rich rewards and that its suppression leads to sterility.

Put in a nut-shell, my thesis amounts to this. The repeated attempts made by Rudolf Carnap to show that the demarcation between science and metaphysics coincides with that between sense and nonsense have failed. The reason is that the positivistic concept of 'meaning' or 'sense' (or of verifiability, or of inductive confirmability, etc.) is inappropriate for achieving this demarcation — simply because metaphysics need not be meaningless even though it is not science. In all its variations demarcation by meaninglessness has tended to be at the same time too narrow and too wide: as against all intentions and all claims, it has tended to exclude scientific theories as meaningless, while failing to exclude even that part of metaphysics which is known as 'rational theology'.

Carnap, who has so far probably advanced the work of the Vienna Circle the most towards empiricism, made an attempt to create a constitutive constructive system; in this he distinguished two languages: a ‘monologizing’ (phenomenalist) one and an ‘intersubjective’ (physicalist) one. He tries to deduce the physical one from the phenomenalist.

Carnap : a language, as e.g. English, is a system of activities or, rather, of habits, i.e., dispositions to certain activities, serving mainly for the purposes of communication and of co-ordination of activities among the members of a group.

Gauss's aim was always to give his investigations the form of perfect works of art. He would not rest sooner and never gave a piece of work to the public until he had given it the perfection of form he desired for it. A good building should not show its scaffolding when completed, he used to say. In his demonstrations he used almost entirely the synthetic method, which he had come to prize through his studies of Archimedes and Newton. It is distinguished from the analytic method by its brevity and comprehensiveness. But the road leading to the discovery remains veiled; and indeed it often seems that Gauss frequently and intentionally turned aside from the road that led to mere instruction.

To sum up: we have seen that of the three notions of 'partial interpretation' discussed, each is either unsuitable for Carnap's purposes (starting with observation terms), or incompatible with a rather minimal scientific realism; and, in addition, the second notion depends upon gross and misleading changes in our use of language. Thus in none of these senses is 'a partially interpreted calculus in which only the observation terms are directly interpreted' an acceptable model for a scientific theory.

I have five minutes left to give you a message to take home. The message is simple. "God forbid that we should give out a dream of our own imagination for a pattern of the world". This was said by Francis Bacon, one of the founding fathers of modern science, almost four hundred years ago. Bacon was the smartest man of his time, with the possible exception of William Shakespeare.

Obsolescence is a fate devoutly to be wished, lest science stagnate and die.

Everything is theoretically impossible, until it’s done. One could write a history of science in reverse by assembling the solemn pronouncements of highest authority about what could not be done and could never happen.

His real dream was to make movies.

The members of the Vienna Circle (Moritz Schlick, Rudolf Carnap, , Hans Hahn, , Fritz Waismann, Kurt Godel, Otto Neurath and others) are working out a ‘Logical Empiricism’. Following Ernst Mach and Poincaré, but above all Russell and Wittgenstein, all the sciences are treated uniformly. Carnap’s Logischer Aufbau der Welt (1928) shows in which direction future systematic work will move. Wittgenstein’s Tractatus Logico-Philosophicus (1921) clarified, among other things, the position of logic and mathematics; besides the statements that make additions to what is meaningful, there are the ‘tautologies’ that show us which transformations are possible within language. By its syntax the language of science excludes anything that is meaningless from the very beginning.

Everything is theoretically impossible, until it is done. One could write a history of science in reverse by assembling the solemn pronouncements of highest authority about what could not be done and could never happen.

...I cannot conceive that a day will come when science will be complete and achieved. There will always be new problems, and exactly at the same pace as science is able to solve problems which were deemed philosophical a dozen years or a century ago, so there will appear new problems which had not hitherto been not perceived as such.

I do remember one formative influence in my undergraduate life. There was an elderly professor in my department who had been passionately keen on a particular theory for, oh, a number of years, and one day an American visiting researcher came and he completely and utterly disproved our old man's hypothesis. The old man strode to the front, shook his hand and said, "My dear fellow, I wish to thank you, I have been wrong these fifteen years". And we all clapped our hands raw. That was the scientific ideal, of somebody who had a lot invested, a lifetime almost invested in a theory, and he was rejoicing that he had been shown wrong and that scientific truth had been advanced. (Part 1, 00:13:32)