K

I've been noticing a rash of threads that seem to go something like this:

Atheist: If God did exist with the traits that Christians normally assign to him, ... (demonstration of logical contradiction).

Christian: That proof is invalid. You've said at other times that you don't believe in God and here you say that He does. You can't have it both ways.

Or, more commonly.

Atheist: If God were truly X and Y, then it would not make sense for Him to do Z... (demonstration of why characteristics X and Y logically contradict action Z).

Christian: The fact that you are so concerned about God doing Z proves you believe in Him.


I didn't see these in the fallacy list although it's highly possible I missed them. Are these common fallacies? I'd never seen anyone use this technique prior to coming to II. But several of the Christians here seem to use it quite a bit.

I'd like to be able just to name the fallacy instead of explaining the process of assuming the opponent's premises and using that to reach a contradiction. It gets really old after about the eighth time.

Does anyone know the name of this fallacy?

MadMordigan

The typical xian bullshit fallacy

Walross

Well, I don't know the name of the fallacy, but the process of assuming you opponent's position, then following the results until you reach a contradiction is known as reductio ad absurdum (sp?) and is not only an acceptable debating technique - it is very much central to formal logic. Anyone who thinks that assuming something for the sake of arguement invalidates your position isn't worth the time it would take to explain this.

Walross

Not Prince Hamlet

Just to expand on Walross's post, the Proof by Contradiction works the following way.

Let's say I'm trying to prove an axiom, x. (for example, "God doesn't exist".)

I'd start with the NEGATION of that axiom (~x, e.g., "God exists"), and build a series of logical inferences from that negated axiom. The goal of a proof by contradiction is to show that this negated axiom leads to a contradiction (for example, leads to both a and ~a, which is a contradiction).

If the negated axiom ("God exists") leads to contradiction, then the original axiom ("God doesn't exist") must be true.

Jeff

I ate Pascal's Wafer

You're lucky. Try spending some time on a Christian board and see what comes up.

I don't know the name of the fallacy offhand either, but I do agree with Walross. If you have to explain to them why you assume their premises, then they probably aren't worth debating anyway.

No use having a battle of the wits with the unarmed.

-Nick

K

What's even worse is having to explain it to the same people over and over again. It seems to sink in, but then two days later, BAM! Same old fallacy again.

Neo

You want a good review of this fallacy and others being used?

Check out this <a href="http://www.bible-discussion.com" target="_blank">FORUM</a>

Neo

I ate Pascal's Wafer

Hehe, that does bug me. I get bummed when I finally think I've explained my point sufficiently and it seems that people are finally coming to their senses thanks to my patience and teaching, and then they pull one of those same fallacies I told them about later on.

I don't know if that's worse than having to explain the same concept to every single person participating in a debate. It's almost like they don't follow what I'm telling other people. It reminds me of that old blonde joke.

A man walks into a bar and orders a drink. As the bartender brings him the beer, the man asks if everyone wanted to hear a blonde joke. The bartender said, "look, mister, I'm 240 lbs and have lifted weights all my life, and I'm blonde. The two people sitting next to you are professional boxers at the top of their game, and they're blonde as well. You see that guy at the table over there? He's a martial arts master and can punch through a brick wall. You guessed it, he's blonde too. Finally the bouncer is 350 lbs and can turn you into a pretzel, and he's also blonde. Do you still want to tell that joke?"

The man replies, "No, not if I'm going to have to explain it 5 times."

Debating the average Christian is so much like this. You have to explain the same concept to every single person over and over. In the end they never make an attempt to understand you and you have only succeeded in wasting a bunch of time. Grr.

-Nick

lpetrich

The fallacy is confusion of evaluating a hypothesis with accepting a hypothesis.

mac_philo

I don't know if this fallacy has a recognized name. I think the discussion of reductio ad absurdum is correct but a bit too specific. This fallacy is really a rejection of the much more general tool called 'conditional proof.'

In formal logic a conditional proof is used to prove conditionals, statements like "if p then q." That statement is true in all cases except when p is true and q is false.

Conditional proof allows one to assume p. After this, any new formula 'q' that can be derive from p and previous formulae allow you to conclude "if p then q."

Then as stated before one performs a reduction ad absurdum by showing that q contradicts something we know to be true, or is internally inconsistent, or what have you.

So it seems their failure is even worse than just rejecting r.a.a. arguments, because they're saying you can't do a conditional proof without *believing* p, rather than just assuming p to see what it entails.