On April 10, 2014, in response to a question, Stephen Maitzen wrote: "I can't see how there could be any law more fundamental than the law of non-contradiction (LNC)." I thought that there were entire logical systems developed in which the law of non-contradiction was assumed not to be valid, and it also seems like "real life" suggests that the law of non-contradiction does not necessarily apply to physical systems. Perhaps I am not understanding the law correctly? Is it that at most one of these statements is true? Either "P is true" or "P is not true"? or is it that at most one of theses statements is true? Either "P is true" or "~P is true"? In physics, if you take filters that polarize light, and place two at right angles to each other, no light gets through. Yet if you take a third filter at a 45 degree angle to the first two, and insert it between the two existing filters, then some light gets through. Based on this experiment, it seems like the law of non-contradiction cannot be true in...

I'm still puzzled by the answers to question 5792, on whether it is true that Mary won all the games of chess she played, when Mary never played any game of chess. Both respondents said that it is true. But is it meaningful to say "I won all the games I played, and I never played any game."? It seems to me that someone saying this would be contradicting himself.

Are there any books or videos or blogs or anything easily accessible that provide actual English translations of symbolic logic? If I could just read some straight-up translations it would be far easier for me to learn symbolic logic. I have some textbooks, but that's not what I'm looking for: I just want translations of sentences. (This was inspired by a reading of Alexander Pruss's "Incompatiblism Proved" of which I tried to paste an example sentence but was unable to do so).

Suppose I have never played a game of chess. If I now make the claim that I've won all the games of chess I've ever played, is that claim true, false, or undefined? A group of friends had an argument over this, and I figured that philosophers are deeply logical thinkers that can give us the answer and also to get a proper understanding of why the answer is what it is.

So I'm reading The Power of Logic, 4th edition. While on a section describing Modus Tollen it says that, Not A; If A, then B; So, Not B is an example of Modus Tollen. My question is how can that be if the conclusion of Modus Tollens is suppose to deny the consequent? Am i reading it wrong or just missing something? Keep in mine im still not beyond chapter 1.

I'm developing a rebuttal to Biblical literalists and I'd like to know whether the following is a recognized/named type of syllogism or other type of argument (and if so, what it's called): Verse X prophesied that would happen happened in verse Y Therefore, the prophecy was fulfilled (If this is not a recognized/named type of syllogism or other type of argument, could it be made so by adding one or two lines?)

What's the difference between understanding an opponent's argument, and agreeing with it? What prevents me from saying that if my opponent disagrees with my argument, he must misunderstand it?

Is it possible for two tautologies to not be logically equivalent?

Someone deliberately advances a fallacious argument in an attempt to advance a cause she considers just. For example, she may treat contraries as if they are contradictories and thus commit a fallacy of false alternatives. Are there any living philosophers who defend the use of "noble fallacies" or "noble fallacious arguments" (and is there a better term for this kind of thing)? And are there any contemporary philosophers who criticize or condemn the practice, including when it is practiced by people who are on "their side" regarding social and political issues?

What is the difference between a conclusion that is "necessarily true, but not false" vs. "necessarily false, but not true"? They seem the same to me or is the answer based on probability? In the same light, what is the difference between "probably not necessarily false" and "probably but not necessarily true"? Thank you, Joe