What is science?

Here are some excerpts about the nature of science:

The old scientific ideal of episteme--of absolutely certain, demonstrable knowledge-has proved to be an idol. The demand for scientific objectivity makes it inevitable that every scientific statement must remain tentative for ever. It may indeed be corroborated, but every corroboration is relative to other statements which, again, are tenative. Only in our subjective experiences of conviction, in our subjective faith, can we be 'absolutely certain'.

The wrong view of science betrays itself in the craving to be right; for it is not his possession of knowledge, of irrefutable truth, that makes the man of science, but his persistent and recklessly critical quest for truth.

Sir Karl Popper, The Logic of Scientific Discovery 

So I left him, saying to myself as I went away: Well, although I do not suppose that either of us knows anything really beautiful and good, I am better off than he is--For the knows nothing, and thinks that he knows . I neither know nor think that I know. In this latter particular, then, I seem to have sightly the advantage of him.


Socrates, in Plato's Apology 


Test everything. Keep what is good.


Saint Paul, First Letter to the Thessalonians