Four Specific Argument Flaws

1. It has counterexamples, i.e., exceptions to so-called "universal" principles.
   

   E.G.: "It's always wrong to kill a human being." Even in self-defense? War?

   E.G.: "All swans are white." Find a non-white swan.

2. It begs the question. This is either to:
   

   A.   Assume without argument the very thing you're trying to prove;

   E.G.: "A fetus is a person, so it's wrong to kill it."

   E.G.: "The world wasn't created by God, because matter has always existed, so the world itself must have always existed."

   OR

   B.   Answer a question with a variation of the very question asked.
   

   E.G.: "Why will this acid make me see things that aren't there?" "Because it has a hallucinogenic effect, dude."

   E.G.: God exists. Why? Because it says so in the Bible. Why should I believe the Bible? Because it's the inspired word of God. (Also known as arguing in a circle, or circular reasoning.)

3. It leads to a contradiction or absurdity (reductio ad absurdam, or just plain reductio). In other words, if we assume a premise or conclusion in the argument to be true, we can show that either (a) a contradiction, or (b) a patently absurd situation must follow. If this is the case, then the original premise or conclusion must be either (a) false (if a contradiction was yielded), or (b) implausible (if an absurdity was yielded).



4. It equivocates, i.e., a key word in the argument shifts its meaning in the course of the argument.
   

   For example:

   A.   Only man is rational.
   B.   No woman is a man.


_______________________________
C.   Thus, no woman is rational.