 The first axiom sets the scale of probability, from 0 to 1, which we can think of as running from 0% probability to 100%  probability.[2]  The second axiom places tautologies at the top of this scale: nothing is more probable than a  tautology.[3]  And finally, the third axiom tells us how to figure out the probability of a hypothesis by breaking it into parts. For example, the probability that an American country will be the first to develop a cure for Alzheimer’s can be figured by adding the probability that a North American country will be first to the probability that a South American country will  be.[4]