Calculating Conditional Probability?

When dealing with probability in causal claims, conditional reasoning seems unavoidable since we will want to know the probability of an effect, if the cause occurs. Conditional probability is typically defined in terms of the ratio of the unconditional probabilities of the elements. But when it comes to cause and effect, there are good reasons to think that this does not hold and that the conditional probability is primitive. It can be shown that a number of problematic but valid inferences from classical logic reproduce in the calculation of conditional probability if the ratio analysis is employed. The primitivist response is to take the conditional connection as unanalysable.