 The general recipe for realism just described is accurate so far as it goes, but still falls short of the degree of precision offered by most realists. The two main sources of imprecision thus far are found in the general recipe itself, which makes reference to the idea of “our best scientific theories” and the notion of “approximate truth”. The motivation for these qualifications is perhaps clear. If one is to defend a positive epistemic attitude regarding scientific theories, it is presumably sensible to do so not merely in connection with any theory (especially when one considers that, over the long history of the sciences up to the present, some theories were not or are not especially successful), but rather with respect to theories (or aspects of theories, as we will see momentarily) that would appear, prima facie, to merit such a defense, viz. our best theories (or aspects thereof). And it is widely held, not least by realists, that even many of our best scientific theories are likely false, strictly speaking, hence the importance of the notion that theories may be “close to” the truth (that is, approximately true) even though they are false. The challenge of making these qualifications more precise, however, is significant, and has generated much discussion.