As it is presented in the passage, the approach to history taken by mainstream U.S. historians of the late nineteenth...

Malia on August 9, 2018

Game 2 Contrapositives

Hi, I am a little confused as to why contrapositive arguments apply to logic games. For instance, in the second game why is it impossible for Hall to visit on day 2 without Jones visiting on day 1? (Same with the Lopez on day 5 and Knight on day 4 scenario.) In these scenarios, the rules on the surface seem to be a one-way street. Thanks in advance!


Michelle on August 16, 2018

Thanks for your question @Malia

One good way to understand why contrapositives apply is to use a simple example. Let's try it with the true statement, "If you are in France, then you are in Europe." We would diagram this statement as follows:

F - > E

Now, we get the contrapositive of a statement by reversing the order of the variables and negating the terms. That would look like this

not E - > not F

"If you are not in Europe, then you are not in France."

Intuitively, we know that to make sense and to be true. But it's more than intuition: it's a logical rule. For any given conditional statement, if it is true then it's contrapositive must also be true.