Universes Paperback – 3 Jul 1996

This is a beautiful little book. Though I can't imagine paying £71.25 for it I also wouldn't sell my own copy for £71.25.Popular science writers and even the occasional professional scientist have written much on the philosophical aspects of frontier physics and cosmology. But curiously, few professional philosophers have much to say these days about where cosmology has been taking us in terms of the truly fundamental questions. Leslie is more or less a lone exception, and in this book he works through the significance and implications of the anthropic cosmological principle in rigorous and systematic terms.The book is a proper philosophical text in that it requires careful reading. but is in no way dense, impenetrable or obscure, and is in fact a model of clarity and could be read by a determined layman. Furthermore the book is illustrated throughout with charming thought experiments that make it a delight to read. The book is self-contained insofar as the basic facts and observations that underlie anthropic thinking are presented briefly and cogently. I in fact read it after reading Barrow and Tipler's far more scientifically technical masterpiece The Anthropic Cosmological Principle (Oxford Paperbacks). As such, Universes helped me to summarise the wealth of detail presented in Barrow and Tipler. However one might just as well read this preparatory to Barrow and Tipler or to some of Leslie's later books that develop his cosmological themes, Modern Cosmology and Philosophy and Infinite Minds: A Philosophical Cosmology.So the essence of the anthropic principle is that we find ourselves in a universe that is 'finely tuned' to an extraordinary degree, and in multiple ways, to support living observers that ultimately, after all the implications have been carefully worked through, leads them to the conclusion that either the single perfect universe was created by a fine tuner, i.e. God in a strictly defined sense as creator, or there are a very large number of universes with random fundamental properties and constants and we living observers inevitably find ourselves in one of the tiny subset that support living observers.The premises are worked through meticulously. What is it in the situation that demands an explanation? What ways are there in which there can be multiple universes? And so on. He makes very clear at the outset that if God is involved then we are talking about a purely creational, designer God. The anthropic principle has nothing to say about God or gods who fiddle with their universe(s) on an ongoing temporal basis or takes any interest in the wellbeing or moral proclivities of any minor parts of its creation. Along the way we are introduced to neoplatonist thought and the ideas of Spinoza who argue that the universe exists because it must, through ethical necessity, and if God is anything then it is, at the very least, that ethical necessity.What I personally admire about Leslie is that he is, like myself, a modern agnostic, who requires that we be very rigorous about what we do know, what we don't know, what we can and can't know, and as such resists the contemporary uges of militant atheism to dismiss the great mystery of the Universe, out of hand, as solved in the name of science. It may be that theoreticians one day come up with a testable hypothesis to determine the existence of other universes. Were it to be proven that there were none then we would be required to live with the alternative, that the universe we inhabit is very, very special and extermely non-random in quantifiable ways. In the meantime anthropic thinking demands that theoreticians take these possibilities into account.