Henry is a member of the varsity football squad. Henry is excused from physical education. We say that the third statement follows logically from the other two. In drawing logical conclusions it does not matter whether the statements we accept as true are reasonable or sensible. This is because we depend entirely upon the form of the statements and not upon what we are talking about.
All whales are subject to colds.
The diagram shows that W is a subset of M as required by statement 1, that M is a subset of B as required by statement 2, and that B is a subset of C as required by statement 3. The only conclusion that uses all of our given statements is that W is a subset of C, as asserted by statement 4. If you have read Alice's Adventures in Wonderland or Through the Looking-Glass , you know that author Lewis Carroll delights in giving sets of nonsense statements which lead to logical conclusions. Nobody is despised who can manage a crocodile. Babies cannot manage crocodiles.