Fine-tuning arguments and biological design arguments: can the theist have both?

There are at least two kinds of design arguments for theism: fine-tuning arguments and biological design arguments. Dougherty and Poston (2008) have argued that the success of one requires the failure of the other, and vice versa. The reason is that the success of these arguments hinges on the following crucial probability: the probability that biological life exists somewhere in the universe given that (a) our universe is finely tuned and that (b) biological development is unguided by intelligence. According to Dougherty and Poston, fine-tuning arguments require that the crucial probability is high while biological design arguments require that the crucial probability is low. As a result, at most one of these design arguments can factor into a cumulative case argument for theism. I argue that this is mistaken. Specifically, I show that fine-tuning arguments can succeed even if the crucial probability is low.