 Mill distinguishes between two main kinds of inductive methods. The method a posteriori is a method of direct experience. In his view, it is only suitable for phenomena in which few causal factors are operating or in which experimental controls are possible. Mill’s famous methods of induction provide an articulation of the method a posteriori. In his method of difference, for example, one holds fixed every causal factor except one and checks to see whether the effect ceases to obtain when that one factor is removed. The goal is to identify exceptionless causal laws.