universatile

Specifically the laws of non contradiction and excluded middle. If you believe these laws then do you not ever answer a question "wellll...yes and no..." because if you do or have you are a hippocrite.

tronvillain

Those laws do not preclude answering a question with "Well, yes and no..." since it is implied that each is intended in a different sense.

Alonzo Fyfe

Question: How many philosophers does it take to screw in a lightbulb?

Answer: It depends on what you mean by "screw in a lightbulb."

The type of problem you describe with the "excluded middle" and the like are typically examples of propositions that are vague (meaning that a term has no clear meaning -- it has fuzzy boundaries) or ambiguous (a term has multiple clear meanings).

Answering "well, yes and know" is another way of saying, "well, it depends on what you mean by ..."

And is a perfectly legitimate answer, not at all ruled out by the rules of logic.

One-eyed Jack

Heh...I believe that Hindu philosophers historically parsed a proposition not as either true or else false but rather as true, false, neither true nor false, or both true and false. And it's been noted (historically by the Skeptics in general and Socrates in particular, I think) that one cannot logically prove that logic itself is trustworthy. (Of course one cannot prove that it's not trustworthy either...the issue is a bit of a dead end.)

[ July 28, 2002: Message edited by: One-eyed Jack ]</p>

Synaesthesia

I think it is in many cases possible to formulate some system of truth or falsity in almost any situation. I think the question is what kind of questions you are asking, and whether you adopt or reject the theoretical framework in which the question is asked.


Is the particle here or there? We can't say, but we can say something true or false about the state of the wavefunction.

Is logic true or false? We can't say, but we can say something about the relative usefulness of different logical systems for different purposes.

Do hobbits have an appendix? I can't say yes or no. I can, however, say that it is true that I cannot say yes or no in answer to the question.

[ July 29, 2002: Message edited by: Synaesthesia ]</p>

owleye

Philosophers before you have challenged such logic. If Quantum theory is meaningful, it is possible these laws do not apply to the universe. Note that quantum theory has been meaningfully transcribed into digital computation (using 2-valued logic, in conformance with this law), and the field of Quantum Chemistry has yielded a successful activity known as Computational Chemistry. Similarly, Quantum Computing makes use of binary-valued logic.

Some philosophers believe rather pessimistically that this suggests a real tension in every truth, with it having irreducible meanings in both sides of every statement. Others, however, think more optimistically and regard such tension as something that needs resolution and not left hanging.

owleye

Adrian Selby

"Do you love your brother who stole your wife from you?"

"Well, yes and no."

Doesn't sound illogical to me, but then not all contexts in which the phrase is used are sensibly scrutinised with the law of the excluded middle.

Adrian

sir drinks-a-lot

I agree that it is the case that the law of contradiction is BS, and I agree that it is not the case that the law of contradiction is BS.

Clutch

Why "BS"?

Holding that LNC is not a logical *law* in some domains is not the same as holding that LNC is "BS". Paraconsistent logicians (dialethicists, as they are now sometimes known) adopt the former view, while the latter is at best unmotivated. ("Weird" is probably a better word.)

Similar remarks apply to LEM: Intuitionists reject it as a law, but are forbidden to produce counterexamples.

Synaesthesia

Within QM, there is a definite fact of the matter regarding the wavefunction. The same does not apply to position.

This goes back to my point that it is very often possible to speak of bivalent truth regarding a system if you change the sort of questions you ask.