In Part 2 we look at the formal rules for reasoning with probabilities. One can think of it as the "logic" of probability.

From a "probability literacy" perspective, the great value of this material isn't the ability to solve technical problems, but rather to clarify the meaning of some important concepts, such as the concept of "independence" (when is the probability of event A independent of the probability of event B?), and the concept of "conditional probability" (what is the probability of event A GIVEN that event B has occurred?).

This material is also fundamental for understanding certain fallacies of probabilistic reasoning.

For example, it's a matter of logic that the probability of two events occurring together is smaller than the probability of each occurring separately. This is one of the rules of probability.

But there are occasions where people come to believe the opposite, that the probability of two events occurring together is actually larger than the probability of each event occurring separately. 

This is known as the "conjunction fallacy". It's a phenomenon that has been studied and discussed by psychologists for many decades. Knowing the basic rules for reasoning about probabilities is a precondition for understanding this fallacy, and why it's incited so much discussion.