As I said in the introduction, I do not intend in this book to add to the existing literature on positivist philosophies of science. We need, however, to look at them briefly in order to set the scene for the growth of the hermeneutic, critical and realist alternatives. One of the best recent books on positivism distinguishes no fewer than twelve senses of the term.¹ For present purposes, however, we can get by with three variants.