Mentat
- 3,935
- 3
Originally posted by Tom
No, and I've never heard of that. Can you explain?
Sure, but you'll probably recognize it, before I'm through.
The paradox of Deductive Logic
Let's take, for example, Euclid's rule: "If two sides of a triangle are equal to the same, they are equal to each other" (I think that's how it goes).
For the purpose of this example, let's say that there is a triangle, where it can be shown that the two sides are equal to the same, but I refuse to believe that they are equal to each other.
Now, you would wish to use deductive logic to show me that it must be so, but...
Proposition 1 is "The two sides are equal to the same"
Proposition 2 is "If two sides are equal to the same, they are equal to each other"
Now, I'll accept those two, but it is another proposition altogether (Proposition [oo]) to say that "Therefore, the two sides are equal to each other". I refuse to accept Proposition [oo], and have no reason to yet. So, you say, "if you accept Propositions 1 and 2, then you must accept Proposition [oo]", which we'll call Proposition 3.
Well, now I'll agree to Propositions 1, 2, and 3, but I still disagree with Proposition [oo], and I don't have to agree with it, because you have yet to say that "if you accept 1, 2, and 3, you must accept Proposition [oo]".
And so it goes on. This is an Inductive approach, in that I am telling you that, no matter how many new propositions you produce, you will still never resolve this paradox.
The paradox of Inductive Logic
This is much more simple. Basically, deductive logic tells us...
1) Inductive Logic is based on learning from observed patterns.
2) What we think is a "pattern" is not necessarily a pattern (it could be a coincidence every time) unless you have tried it as many times as possible (which is infinite, obviously).
3) Therefore, Inductive Logic is based on trying something an infinite amount of times, and is thus not "proof" of anything.
It's called Logic, by David Baum. Just a first textbook on the subject.
So far, we slowly crawled through the introduction, and we are about half way through the first of two chapters on syllogistic logic. I'll post some more by the end of the week.
Thanks. It's very interesting to me.
I really want to get to symbolic logic, because that's where the power of deductive reasoning gets a huge boost.
Yeah, I've had some dealings with symbolic logic before (mostly in Raymond Smullyan's books, which I highly recommend, btw), and I think it's probably one of the most interesting things I've studied.