British Journal for the Philosophy of Science, 2005, 56(4): 809–21
Elliott Sober argues that the cosmological design argument is unsound, since our observation of cosmic fine-tuning is subject to an observation selection effect (OSE). I argue that this view commits Sober to rejecting patently correct design inferences in more mundane scenarios. I show that Sober’s view, that there are OSEs in those mundane cases, rests on a confusion about what information an agent ought to treat as background when evaluating likelihoods. Applying this analysis to the design argument shows that our observation of fine-tuning is not rendered uninformative by an OSE.