You should use probabilities, actually. And while step 4 is not a logical consequence, it may have substantial probability, per Bayes' theorem: P(C | A) = P(

You should use probabilities, actually. And while step 4 is not a logical consequence, it may have substantial probability, per Bayes' theorem: P(C | A) = P(A | C) * P(C) / P(A)