Logic In Argumentative Writing

Argumentative writing is – obviously – writing which argues a point. A thesis (that’s the point that is being proven) is given, and then some reasons to support the thesis are explained. The thesis and reasons pre-suppose a few logical things, though; if they didn’t, we wouldn’t ever be able to prove something.

The philosopher Aristotle came up with one of our most common formulae for logic:

• Premise 1: All men are mortal.
• Premise 2: Socrates is a man.
• Conclusion: Socrates is mortal.

Human brains always work on the Aristotelian premise. If your argument doesn’t quite work out that way, it’s considered illogical (and, therefore, it can’t be proven).

• Premise 1: Rock is heavy.
• Premise 2: The statue is made out of rock.
• Conclusion: The statue is heavy.

Well, when the smirking guy next to us holds up a chunk of pumice (which is a light-weight volcanic rock), we know he’s going to blow this argument out of the water. Logically, we have to be more specific:

• Premise 1: A 5x7 chunk of solid marble is heavy.
• Premise 2: The statue is made out of a 5x7 chunk of solid marble.
• Conclusion: The statue is heavy.

There are people who could find fault with this argument, too, but the average reader would deem it a logical conclusion.

Make sure your argument is logical right to the end. If A causes B which causes C, then we expect Y to cause Z. If Y doesn’t cause Z, then your argument is illogical (the philosophical term for this is slippery slope).

Readers are also on the look-out for writers attempt to cover up their lack of logic. Here are some terms used for illogical conclusions:

• Hasty Generalization: when an incorrect conclusion which is reached through a limited number of premises. (Did anyone even check to see what the statue was made of? Is the statue actually heavy?)
• Circular argument: when an argument is just restated rather than proved. (Rock is heavy; the statue is made out of rock; rock is heavy, the statue is made out of rock.)
• Ad hominem: when the writer attacks the person rather than the facts (That guy doesn’t know anything about rocks or statues.)
• Ad populum: when the writer appeals to the reader’s emotions rather than using facts. (That guy with the pumice stone has a long criminal record, and he eats kittens for breakfast!)
• Red Herring: when a writer makes the reader pay attention to something other than the facts. (Michelangelo carved a lot of heavy statues.)
  

When you have your logical premises and conclusion, the conclusion becomes the thesis of your argument, and the premises become the supporting points. See Organizing and Developing Your Ideas.