The Trilemma Argument - Part 3: The Argument for Premise (1)

DILEMMA ARGUMENTS vs. TRILEMMA ARGUMENTS 

A dilemma argument is an argument that starts out by specifying two alternatives as being the only possibilities, then eliminates one of the alternatives, and then concludes that the other alternative must be true:

Either the butler killed Mr. Jones or the maid killed Mr. Jones.

The butler did not kill Mr. Jones.

THEREFORE:

The maid killed Mr. Jones.

A trilemma argument is an argument that starts out by specifying three alternatives as being the only possibilities,  then eliminates two of the alternatives, and then concludes that the one remaining alternative is true:

Either the butler killed Mr. Jones or the maid killed Mr. Jones or the gardener killed Mr. Jones.

The butler did not kill Mr. Jones.

The maid did not kill Mr. Jones.

THEREFORE:

The gardener killed Mr. Jones. 

The core of the Trilemma Argument for the deity of Jesus has the same logical structure:

1. Either (a) Jesus is God, or (b) Jesus lied about being God, or (c) Jesus was seriously mentally ill.

2. It is not the case that: Jesus lied about being God.

3. It is not the case that: Jesus was seriously mentally ill. 

THEREFORE:

4. Jesus is God.

THE DILEMMA BEHIND THE TRILEMMA

The most important historical claim in the Trilemma Argument occurs in the first sentence of the chapter where the McDowells lay out the Trilemma:

ONCE I (JOSH) CONCLUDED THAT JESUS CLAIMED TO BE GOD, I realized I only had so many options left. (EFJ, page 64)

A key historical claim of the Trilemma Argument is this: 

Jesus claimed to be God.

From this claim, the McDowells infer a dilemma:

…Jesus’ claim to be God must be either true or false.  (EFJ, page 65)

I will restate this claim so that each alternative of the dilemma is spelled out:

Either Jesus' claim to be God was true, or Jesus claim to be God was false.

The McDowells turn this dilemma into a trilemma by dividing the second alternative into two possibilities:

But if Jesus’ claims to be God were false, then we are left with just two options: he either knew his claims were false (he was a liar), or he did not know they were false (he was crazy). (EFJ, page 65) 

I will restate this assertion more simply and concisely (leaving out the added inferences about Jesus being a liar or being crazy):

If Jesus' claim to be God was false, then either Jesus knew his claim to be God was false or Jesus did not know his claim to be God was false (though it was false). 

THE SUB-ARGUMENT FOR AN INITIAL TRILEMMA 

We may now state the argument for an initial trilemma:

5. Jesus claimed to be God.

THEREFORE:

6. Either Jesus' claim to be God was true, or Jesus' claim to be God was false.

7. If Jesus' claim to be God was false, then either Jesus knew his claim to be God was false or Jesus did not know his claim to be God was false (though it was false).

THEREFORE:

8. Either (a) Jesus' claim to be God is true, or (b) Jesus knew his claim to be God was false, or (c) Jesus did not know his claim to be God was false (though it was false).

We can now diagram the logical structure of the sub-argument for the initial trilemma, premise (8):

THE SUB-ARGUMENT FOR PREMISE (1) 

In order to arrive at the trilemma statement used in the core of the Trilemma Argument, the McDowells make inferences from each of the three alternatives stated in the initial trilemma, premise (8):

If Jesus' claims [to be God] were true, then he is Lord. (EFJ, page 65) 

If Jesus knew he was not God, then he was lying. (EFJ, page 65) 

...or he [Jesus] did not know they [his claims to be God] were false (he was crazy). (EFJ, page 65) 

Let's clarify these three statements so that they are clear and use the same expressions as the previously clarified premises: 

9. If Jesus' claim to be God was true, then Jesus is God.

10. If Jesus knew his claim to be God was false, then Jesus lied about being God.

11. If Jesus did not know his claim to be God was false (though it was false), then Jesus was seriously mentally ill. 

If we add these three claims to the initial trilemma statement, premise (8) above, we can infer the key statement of the trilemma in the core of the Trilemma Argument:

1. Either (a) Jesus is God, or (b) Jesus lied about being God, or (c) Jesus was seriously mentally ill.

We can now diagram the logical structure of the sub-argument supporting premise (1) in the core of the Trilemma Argument:  

If we add the core of the Trilemma Argument to the above two diagrams, we can diagram the whole Trilemma Argument, minus the reasons/arguments for premises (2) and (3):