Forum:What makes logic valid?

I was just in a debate over why logic and reason should be considered valid for scientific purposes on a flat earth society forum (of all places to be discussing logic). My opponent insisted that logic/reason merely assert themselves to valid and are therefore circular in nature. I pointed out that logic and reason were based in proof and therefore should be valid. However he continued to argue and eventually I just dismissed his argument by stating that he cannot logically state that logic is invalid by using logic because than his own argument becomes circular.

However, I was never able to directly answer him and it did get me thinking about why logic is valid...any thoughts? Gckaufman (talk) 04:06, 2 August 2013 (UTC)


 * Just off the top of my head: Much like the scientific method itself, we use it (and we assume it is valid) because it's the best available tool we know of and it demonstrably works. Sure, it's an assumption, but it's an assumption that functions and is at the cornerstone of most arguments and discussions we have, and there's no compelling reason for it to be discarded. For the more in-depth stuff, Wikipedia has some coverage on “Is logic empirical?”, which honestly goes way over my head but might make sense to you if it turns out it's relevant. AntiDeathPill (talk) 14:03, 2 August 2013 (UTC)
 * I suggest looking at the Stanford Encyclopedia of Philosophy: http://plato.stanford.edu/entries/logic-classical/
 * Also, Ethan Allen: Those who invalidate reason, ought seriously to consider, "whether they argue against reason, with or without reason; if with reason, then they establish the principle, that they are laboring to dethrone;" but if they argue without reason, (which, in order to be consistent with themselves, they must do,) they are out of the reach of rational conviction, nor do they deserve a rational argument. Your opponent seems to have fallen into the first case. :) --ZooGuard (talk) 09:01, 5 August 2013 (UTC)
 * Also, Ethan Allen: Those who invalidate reason, ought seriously to consider, "whether they argue against reason, with or without reason; if with reason, then they establish the principle, that they are laboring to dethrone;" but if they argue without reason, (which, in order to be consistent with themselves, they must do,) they are out of the reach of rational conviction, nor do they deserve a rational argument. Your opponent seems to have fallen into the first case. :) --ZooGuard (talk) 09:01, 5 August 2013 (UTC)


 * You can make hypotheses and predictions based on at and they are true. (Agrajag (talk) 20:23, 1 August 2014 (UTC)|Agrajag)
 * Logic has to start somewhere, i.e. a priori premises. Unless you are WVO Quine, of course... Nebuchadnezzar (talk) 21:46, 1 August 2014 (UTC)
 * The way I've always thought of it, the reason we use logic is because it is the most logical option. Given that this is recursive, I have come to the conclusion that whenever you logically follow a logical train of thought, you eventually hit a point where you either use an irrational premise, or you end up in a recursive loop.  Even a Spock archetype would have to eventually bring in illogical premises.  Example- Q: Why did you join the police force?  A: It will keep the most people safe.  Q: Why keep the most people safe?  A: It best protects the overall health of the people.  Q: Why protect the people's health?  A: It is the most moral thing to do.  Q: Why act morally?  A: It keeps me in high standing in society.  Q: Why keep high standing?  A: It is most advantageous to me in the long run.  Q: Why be advantageous?  A: It best benefits me.  Q: Why benefit yourself?  A: Uhhhhhhhh...  OVERLORD  Supplicate yourselves before me!  05:20, 14 February 2015 (UTC)

Define terms. Always define terms
On some level, at least a superficial one, you seem to think the words you're using mean something. And not only that, communicate something to us in a way we understand. So when you say "what makes logic valid", you're including, by intuition some assumptions about what "logic" and "valid" mean. I can hazard a guess that you mean by logic "formal logical systems" and by valid, you mean "acceptably demonstrated as an idea".

Of course those definitions in turn require definitions. But that's not the point. The point is the essence that you and I, simply demonstrated by our conversation, understand each other to one degree or another.

Logic is typically composed of truths so palpably self-evident that you can't construct our idea of a dialog without them. Then beginning to apply those ideas to themselves to build a framework of mutually understood truth. One of those truths, merely by example, is that an assertion cannot simultaneously be both absolutely true and absolutely untrue at the same time, which allows for the logical framework of proof by contradiction. You could disagree with this. There's nothing to stop you from asserting that this is untrue, but it's so intuitive to how we approach both our own thoughts(cogito ergo sum) and the world around us, that the denial would serve no discernible purpose.

In the end, logic exists as a system of expressing and relating thoughts, not any sort of fundamental truth. Logic doesn't exist in cold, unfeeling, empty space. If you reject that system, you do so in an a vacuum of stated alternatives. We have natural language, certainly, that predates logic as a means of representing ideas, but we can intuit and locate flaws in natural language for representing ideas. Ambiguities, lack of ability to construct new or temporary frameworks to express more complex ideas in, and the subjective interpretation of ideas. Logic declares for itself, a single way of understanding the expression of an idea. To precisely define the elements at play. Logic isn't "valid", logic is "more useful than how we did things before". Ikanreed (talk) 20:54, 1 August 2014 (UTC)


 * Read some Godel and make up your own mind. DS 31.52.208.210 (talk) 21:55, 7 September 2014 (UTC)
 * That is to say "I think the completeness theorems mean 'make up whatever you want, and obviously that's equal to logic'". Also you didn't even read my post.  Ikanreed (talk) 19:57, 8 September 2014 (UTC)