Prior probabilities and confirmation theory: a problem with the fine-tuning argument

Abstract

Fine-tuning arguments attempt to infer God’s existence from the empirical fact that life would not be possible if any of approximately two-dozen fundamental laws and properties of the universe had been even slightly different. In this essay, I consider a version that relies on the following principle: if an observation O is more likely to occur under hypothesis H1 than under hypothesis H2, then O supports accepting H1 over H2. I argue that this particular application of this principle is vulnerable to straightforward counterexamples and attempt to explain the proper application conditions for this principle.