This is very reminiscent of presuppositional apologetics.

I'm so happy. This is the first time I've ever gotten to charge this fallacy in my entire history on ODN.

You have committed the logical fallacy of

*modus tollens*, also known as affirming the consequent. It's slightly more subtle than a simple

*modus tollens*, but it is logically equivalent.

Firstly, we need to discuss the nature of

*valid* implication. Let's call some proposition P, and then a second proposition Q. Let's also accept the premise that:

*"If P is true, then Q is true."*

Which is to say, "P implies Q." So, what this relationship tells us is that if P is true, then it must also be true that Q is true. But what happens if Q is true? Does this mean that P is true?

The logical answer is "No," but let's give a pretty intuitive example for why:

1. "If I'm in Germany, then I am in Europe."

2. "I'm in Europe."

3. "Therefore, I'm in Germany."

We could be in France, Italy, etc. There are only two possibly valid arguments coming from implication (without some other caveats, but I'll ignore them for simplicity because they don't matter here):

*1. *Modus Ponens

A. "If P is true, then Q is true"

B. "P is true."

C. "Therefore, Q is true."

And the logically equivalent (note, if you can't draw a logical conclusion from one logically equivalent statement, you'll never be able to draw it from another):

*2. Contrapositive to *Modus Ponens* (this is logically equivalent)*

A. "If P is true, then Q is true."

B. "Therefore, if Q is false, then P is false."

C. "Q is false."

D. "Therefore, P is false."

You're committing a

*modus tollens* fallacy on the converse

*modus ponens*. Before you ask, no, I don't expect that you recognize this at first, so let's trot this out:

1. "If God is true, then X is true."

2. "Therefore, if X is false, then God is false."

3. "God is false."

4. "Therefore, X is false."

One is your opening premise, that there are certain truths that come out of God's existence. 2, you'll have to take my word on this if you don't see why this immediately follows, is true by nature of the fact that 1 is true. 3 is the our pretend-true assertion. However, then, you affirm the consequent by trying to then argue that you

*can* get this conclusion.

So finally, completely concretely, here's an example of the invalidity of your argument:

*1. "If God is true, then logic is true."*

2. "Therefore, if logic is false, then God is false."

3. "God is false."

4. "Therefore, logic is false."

This is obviously a false statement. The only statements which would be false statements are statements which are true if,

*and only if*, God is true.

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