Critical thinking evaluates the validity of propositions. It is the hallmark and the cornerstone of science because science is a community that aims to generate true statements about reality. The goals of science can be achieved only by engaging in an evaluation of statements purporting to be true, weeding out the false ones, and limiting the true ones to their proper contexts. Its centrality to the scientific enterprise can be observed in the privileges accorded to critical thinking in scientific discourse. It usually trumps all other considerations, including tact, when it appears in a venue that considers itself to be scientific.

A proposition is a statement that claims to be true, a statement that claims to be a good guide to reality. Not all statements that ...