I hold that the propositions embodied in natural science are not derived by any definite rule from the data of experience, and that they can neither be verified nor falsified by experience according to any definite rule.

My title is intended to suggest that the community of scientists is organized in a way which resembles certain features of a body politic and works according to economic principles similar to those by which the production of material goods is regulated.

Admittedly, scientific authority is not distributed evenly throughout the body of scientists; some distinguished members of the profession predominate over others of a more junior standing.

We could not, for example, arrive at a principle like that of entropy without introducing some additional principle, such as randomness, to this topography.

And the actual achievements of biology are explanations in terms of mechanisms founded on physics and chemistry, which is not the same thing as explanations in terms of physics and chemistry.

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.

But even physics cannot be defined from an atomic topography.