The title misled me into thinking that this book would offer a careful consideration of what made some scientific ideas "seem good at the time." Unfortunately, this is only true of a few of the vast number of outdated ideas considered in this book. The author intends, apparently, to be encyclopedic--everything is considered here, even things no one would claim were ever thought to be scientific hypotheses (e.g., cannibalism to acquire the powers of one's enemies). However, like an encyclopedia, most entrees are brief, the exceptions being the ones the author seems a little obsessed by (intelligent design and religion in general get bashed repeatedly, sometimes amusingly, but usually in a way that makes you embarrassed for the author). George Bush gets beat up a fair number of times too, for related reasons, but this betrays the polemic character of the book, which is often condescending (in the spirit of "look at these quaint or irrational ideas... we know so much better now, unless you're a Christian fundamentalist moron!") (Incidentally, I'm not.) As a scientist myself--I teach physics at the College level--I expected more rigor to the criticisms and more scholarship. For example, not a single quotation comes with a page citation, and several quotations are not mentioned at all in the Bibliography). In short, an easy read, but disappointing.