Question

If a then it cannot fail to be the case that b. This statement is in fact ambiguous and there are apparantly two ways of interpreting this:

If a is true then b is necessarily true
If a then it cannot fail to be the case that b.
The author gives an example with a person being married and getting divorced: If John is getting divorced, he is married; but it is certainly not true that if John is getting a divorce he is necessarily (irrevocably) married.I don't quite see the difference between the two statements. I am sure it has something to do with the irrevocably. But where does the irrevocably come from?

Answer 1

The statement 'If a then it cannot fail to be the case that b' can be interpreted in two ways: if a is true, then b is necessarily true, or if a then it cannot fail to be the case that b. The difference lies in the possibility of b being true for other reasons.

Step-by-step explanation:

The statement 'If a then it cannot fail to be the case that b' is ambiguous and can be interpreted in two ways:

1. If a is true, then b is necessarily true. This means that the truth of a guarantees the truth of b.
2. If a, then it cannot fail to be the case that b. This means that a implies b, but b might also be true for other reasons.

In the example with John getting divorced, 'if John is getting divorced, he is married' shows that being married is a necessary condition for getting a divorce.

However, it is not irrevocably married, meaning that John could be married for other reasons even if he is getting a divorce.