Fine-Tuning Indexical Evidence

Do recent advances in reasoning with self-locating evidence defeat the "this-universe objection" to fine-tuning arguments for a multiverse? Philosophers such as Isaacs, Hawthorne, and Russell have argued that they do, claiming that on any plausible rule for updating on self-locating evidence, the statement "I exist in a fine-tuned universe" confirms the multiverse hypothesis. I argue that such approaches obscure the distinction between the evidential import of this universe's existence and that of its fine-tuning. To advance the debate, I develop a general formal framework that models both de se ("I") and demonstrative (e.g. "this universe") evidence. I provide a general proof that any rule for reasoning with such information that respects a plausible principle of indifference entails that the fine-tuning of this universe provides no positive, independent support for a multiverse.