Like many other philosophers I am at times inclined to classify philosophers as belonging to two main groups—those with whom I disagree, and those who agree with me.
- C&R, page 309

I shall give here a somewhat unsystematic list of six types of cases in which we should be inclined to say of a theory t1 that it is superseded by t2 in the sense that t2 seems—as far as we know—to correspond better to the facts than t1 , in some sense or other.

• t2 makes more precise assertions than t1 , and these more precise assertions stand up to more precise tests.
• t2 takes account of, and explains, more facts than t1 (which will include for example the above case that, other things being equal, t2 ’s assertions are more precise).
• t2 describes, or explains, the facts in more detail than t1 .
• t2 has passed tests which t 1 has failed to pass.
• t2 has suggested new experimental tests, not considered before t 2 was designed (and not suggested by t1 , and perhaps not even applicable to t1 ); and t 2 has passed these tests.
• t2 has unified or connected various hitherto unrelated problems.

- C&R, page 315

Let me first say that I do not suggest that the explicit introduction of the idea of verisimilitude will lead to any changes in the theory of method. On the contrary, I think that my theory of testability or corroboration by empirical tests is the proper methodological counterpart to this new metalogical idea. The only improvement is one of clarification.
- C&R, page 318

Consciousness, world 2, was presumably an evaluating and discerning consciousness, a problem-solving consciousness, right from the start. I have said of the animate part of the physical world 1 that all organisms are problem solvers. My basic assumption regarding world 2 is that this problem-solving activity of the animate part of world 1 resulted in the emergence of world 2, of the world of consciousness. But I do not mean by this that consciousness solves problems all the time, as I asserted of the organisms. On the contrary. The organisms are preoccupied with problem-solving day in, day out, but consciousness is not only concerned with the solving of problems, although that is its most important biological function. My hypothesis is that the original task of consciousness was to anticipate success and failure in problem-solving and to signal to the organism in the form of pleasure and pain whether it was on the right or wrong path to the solution of the problem.

• In Search of a Better World, p.17 (emphasis added)

The criterion of potential satisfactoriness is thus testability, or improbability: only a highly testable or improbable theory is worth testing, and is actually (and not merely potentially) satisfactory if it withstands severe tests—especially those tests to which we could point as crucial for the theory before they were ever undertaken.
- C&R, Chapter 10

Consequently there is little merit in formalizing and elaborating a deductive system (intended for use as an empirical science) beyond the requirements of the task of criticizing and testing it, and of comparing it critically with competitors.
- C&R, Chapter 10

Admittedly, our expectations, and thus our theories, may precede, historically, even our problems. Yet science starts only with problems. Problems crop up especially when we are disappointed in our expectations, or when our theories involve us in difficulties, in contradictions; and these may arise either within a theory, or between two different theories, or as the result of a clash between our theories and our observations.
- C&R, Chapter 10