The Difference Between Science and Pseudoscience

What I had in mind was that his previous observations may not have been much sounder than this new one; that each in its turn had been interpreted in the light of "previous experience," and at the same time counted as additional confirmation. What, I asked myself, did it confirm? No more than that a case could be interpreted in the light of a theory. But this meant very little, I reflected, since every conceivable case could be interpreted in the light Adler's theory, or equally of Freud's. I...

 Karl Popper's Conclusions About Good Theories

It is easy to obtain confirmations, or verifications, for nearly every theory — if we look for confirmations.     Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory — an event which would have refuted the theory.     Every "good" scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the ...