 Instead of ranking collections of truths by two measures, strength and simplicity, we will rank them by three, strength, simplicity and fit. A collection of truths that entails that what does happen has (at earlier times) a higher chance of happening has better fit than a collection that entails that what happens had a lower chance of happening. The laws are those generalisations in the collection of truths that do the best by these three measures of strength, simplicity and fit. The collection will entail various ‘history-to-chance’ conditionals. These are conditionals of the form If Ht then Pt(A) = x, where Ht is a proposition about the history of the world to t, and Pt is the function from propositions to their chance at t. The chance of A at t in w is x if and only if there is some such conditional If Ht then Pt(A) = x, where Ht is the history of w to t.