### Abstract

People often confuse probabilities with their inverses. Many inductive arguments require us to reason about inverse probabilities. ‘Inverse probability: you can’t be indifferent about it!’ looks at the relationship between inverse probabilities, illustrating it with the Argument to Design, which asks: does not the fact that the physical cosmos is ordered in the way that it is give us reason to believe in the existence of a god of a certain kind? Logicians use the term Principle of Indifference to describe an important part of intuitive reasoning about probability: given a number of possibilities, with no relevant difference between them, they all have the same probability.