Thursday, March 20, 2008

logical details

While many people just don't care about formal logic, I just sat through an hour and a half of discussion that was based on an argument with so many logical fallacies that my brain almost exploded. I don't claim to be a logical person (I occationally claim to be practical). But inspite of my personality defects, I understand logic. Let me just construct the argument that I was witness to today:

If you are a prostitute, then you sell yourself.
If you sell yourself, then you are a prostitute.
Therefore, we are all prostitutes.

If you read this and say, "Well, that's not SO bad." That's okay. It didn't bother a lot of poeple in my class today. But I hope you will see the ridiculousness of the argument when I create some another scenarios using the same logic. In the first two lines, the conclusion violates the conditional. It's like saying:

If you are a fat, ugly, rabid, stupid dog, then you are a mammal.
If you are a mammal, then you are fat, ugly, rabid, stupid dog.
Therefore, you are all fat, ugly, rabid, stupid dogs.
(btw, you, reading this blog, are a mammal. I hope you take offense to this logical fallacy)

If you get into Yale Law, you took the LSAT.
If you take the LSAT, you will get into Yale Law.
Therefore, we are all Yale Law students.
(a favorite of my ACE prep course teacher's)

Clearly, this kind of logic could get you into trouble. But what I hated the most, and what we spent the entire class discussing was "We are all prostitues." We were discussing a conclusion that we never should have arrived at in the first place. We aren't all fat, ugly, rabid, stupid dogs. We aren't all Yale Law students. And if we pay attention to the details of formal logic, we know that we aren't all prostitutes either. 

if you think of other arguments that parallel this argument, I would love to hear them.

No comments:

Post a Comment

I try to respond to comments if I have your email :)