Should we care about fine-tuning?

There is an ongoing debate over cosmological fine-tuning between those holding that design is the best explanation and those who favor a multiverse. A small group of critics has recently challenged both sides, charging that their probabilistic intuitions are unfounded. If the critics are correct, then a growing literature in both philosophy and physics lacks a mathematical foundation. In this paper, I show that just such a foundation exists. Cosmologists are now providing the kinds of measure-theoretic arguments needed to make the case for fine-tuning. Introduction Probability and infinite sets 2.1 No probability function 2.2 Arbitrary and wrong probability functions The measure of the universe The coarse-tuning objection Arbitrariness and error Conclusion.