Chapter 1: Introductory Remarks on Explanation, Idealization, and Ineliminability

For the most part, scientific explanations are answers to why-questions. A scientific explanation of some phenomenon P answers the question ‘Why is it the case that P obtains? ’ One might ask why straight sticks appear to be bent when immersed in water, why some metals become magnetic, why the moon eclipses the sun, etc. Science aims to answers these questions. This explanatory task goes beyond the descriptive task of science, because explanations do not merely describe what is the case; they also show why it is the case. A scientific explanation can be thought of as a set of sentences, one of which – the explanandum – stands in a certain relation to the others – the explanans. The explanandum is a sentence to the effect that the phe-nomenon to be explained obtains; there is always a presupposition that the explanandum is true, because there is no explanation of why a false sen-tence is true nor of why a phenomenon that does not obtain obtains. The explanans is the set of sentences that purport to explain the explanandum