Theories of evolution must provide for the creative acts which brought such theories into existence.

We know more than we can tell.

Personal participation is the universal principle of knowing.

I shall reconsider human knowledge by starting from the fact that we can know more than we can tell.

Human beings exercise responsibilities within a social setting and a framework of obligations which transcend the principle of intelligence.

The first thing to make clear is that scientists, freely making their own choice of problems and pursuing them in the light of their own personal judgment, are in fact co-operating as members of a closely knit organization.

Our reliance on the validity of a scientific conclusion depends ultimately on a judgment of coherence; and as there can exist no strict criterion for coherence, our judgment of it must always remain a qualitative, nonformal, tacit, personal judgment.