Question

There is an old joke that goes something like this: “If God is love, love is blind, and Ray Charles is blind, then Ray Charles is God.” Explain, in the terms of first-order logic and predicate calculus, why this reasoning is incorrect. If the person who told you this joke was your grandmother, how would you respectfully explain this to her?

Answer 1

Let God = A
Love = B
Blind = C
Ray Charles = D

Answer 2

((A->B) ^ (B->C) ^ (D->C)) -> (D->A)

Answer 3

A->B and B->C, then A->C.
But A->C cannot be made C->A, as this is the logical fallacy of affirming the consequent.

Answer 4

So D->C cannot become D->A, as C cannot be exchange for A as per the above reason.

Answer 5

Thus the reasoning is incorrect.

Answer 6

The symbol -> denotes an if-then statement, by the way.

Answer 7

Thumbs up!
How awesomely you explained!