“Fine-Tuning and the Problem of Old Evidence”

The fine-tuning argument is one of the most important arguments for the existence of God. By and large, it relies on two key claims. First, we allegedly have evidence that the fundamental constants of our Cosmos are fine-tuned. More precisely, the proponents of this argument claim that those constants described by laws of physics should be within some narrow range of values in order to allow the emergence of intelligent life. If those fundamental constants were otherwise different to some degree, then the universe would not be life-permitting. Second, apparently it is very improbable that our Cosmos supports life merely by chance. So, it is more probable that our Cosmos is hospitable to life given that there is a God than given that there is no God. In this paper, assuming that the fine-tuning argument is better modeled by using the formal machinery of Bayesian confirmation theory, I examine a problem of great significance against it, the so-called problem of old evidence. In the face of this problem, I survey some potential responses to it by exploring a set of alternative measures of confirmation available in the technical literature, such as the log-ratio measure and the log-likelihood ratio measure. I also discuss some objections against a thesis that the proponents of the fine-tuning argument usually argue for, namely that the proposition that there is a God increases the probability that the universe is life-permitting.