Not if they really are necessary truths. By definition, any necessary truth couldn't possibly have been false. It takes some care to state propositions in such a way that they really are necessarily true. For instance, Red is a color asserts the existence of something -- red, or redness -- that arguably doesn't exist in every possible world. If there are possible worlds in which nothing physical ever exists, then nothing is red or (arguably) even could be red in such worlds, making it unclear whether there is a color red in such worlds. By contrast, the necessarily true proposition Whatever is red is colored doesn't assert the existence of anything, so it comes out (vacuously) true even in worlds lacking any red or colored things.
Given a particular conclusion, we can, normally, trace it back to the very basic premises that constitute it. The entire process of reaching such a conclusion(or stripping it to its basic constituents) is based on logic(reason). So, however primitive a premise may be, we don't seem to reach the "root" of a conclusion. Do you believe that goes on to show that we are not to ever acquire "pure knowledge"? That is, do you think there is a way around perceiving truths through a, so to say, prism of reasoning, in which case, nothing is to be trusted?
It's not clear to me what you're asking, but I'll do my best. Given a particular conclusion, we can, normally, trace it back to the very basic premises that constitute it. I doubt we can do that without seeing the conclusion in the context of the actual premises used to derive it. The conclusion Socrates is mortal follows from the premises All men are mortal and Socrates is a man , but it also follows from the premises All primates are mortal and Socrates is a primate . So which pair of premises are "the very basic premises" for that conclusion? Outside of the actual argument context, the question has no answer. I don't know what you mean by "the root of a conclusion," but you seem to be suggesting that any knowledge is impure if it depends on -- or if it was acquired using -- any reasoning at all. Perhaps the term inferential would be a better label for such knowledge. On this view, even if I have direct knowledge that I am in pain (when I am), I have only...
I would just like to ask. Is truth relative? Personally, I don't think it is because the question begs you to believe there are instances where it is false which means it is not constantly applicable which makes me question it. However, I find a flaw that I can't quite answer. Let's say something that is true on a specific culture, is false on another, if this is the case, then how could truth be absolute? Or is truth actually relative?
I can't make sense of the idea that truth could be relative. Suppose that I find some dish spicy, while you find it mild. We might be inclined to say that (R) "This dish is spicy" is true relative to me and false relative to you, but I think that way of speaking is by no means forced on us and, in fact, is misleading. For if R itself were true, its truth would have to be explained in terms of the truth of this non-relative claim: (NR) This dish is spicy relative to my taste but not yours. NR neither is nor implies the claim that truth is relative. Rather, perceived spiciness is. So too with (P) "Polygamy is acceptable" is true relative to culture A but false relative to culture B. P is an avoidable and misleading way of making the non-relative claim that culture A accepts polygamy whereas culture B doesn't. The acceptance of polygamy is relative to culture, and that's a non-relative truth.
Logic plays an important role in reasoning because it helps us out to evaluate the soundness of an argument. But logic doesn't help us out in the search of truth. Does philosophy have a method/s to find truth ? Is something like truth possible in philosophy ? I just would like to know because, as a guy who studies such a subject, I tried to answer these questions without success. I lack the necessary resource to answer such a question (a definition of truth). By the way, I'm sorry for the bad English; it's not my native language.
I respectfully disagree with your claim that logic doesn't help in the search for truth. On the contrary, we need logic in order to find out what any proposition P implies -- what other propositions must be true if P is true -- which, in turn, is essential for verifying that P itself is true. This holds as much in science as in philosophy or any other kind of inquiry. You suggest that you need a definition of the word truth before you can answer the question whether philosophy can find truth. But if that's a problem, it isn't a problem just for philosophy: it affects science and any other kind of inquiry just as much as it affects philosophy. You could say to a physicist, "Until I have a definition of truth , how can I know whether physics can find truth?" The only difference here between philosophy and physics is that a philosopher will take your question seriously. I don't think you need a definition of truth -- or at any rate not an interesting definition -- in order to see...
Is it possible to employ a truth predicate or truth set (set of all true propositions) in ordinary first order logic?
To my knowledge, no. Ordinary first-order logic quantifies only over individuals (none of which are literally true) rather than over truth-valued things such as sentences or propositions. Thus there's nothing in first-order logic to which the predicate "is true" can apply. For that you need higher-order logic, which is a topic of controversy in its own right. By "set of all true propositions," I take it you mean "a set of all the true propositions there are," i.e., the extension of the predicate "is a true proposition." A Cantorian argument due to Patrick Grim concludes that no such set is possible. It works by reductio . Let T be any set containing all of the true propositions. If T exists, then it has infinitely many members, but that doesn't affect the argument. Now consider the power set of T -- P(T) -- which is the set whose members are all of the subsets of T. It's provable that any set has more subsets than it has members. With respect to each of those subsets in P(T), there is a true...
I suppose it is very difficult do define "truth" in an informative way (without just giving a synonym or something like that). Can you explain why it is so? Or is it easy?
One reason that it's difficult to define "truth" might be that the word stands for a concept that's too basic, too fundamental, to be informatively defined in terms of other concepts. I myself think that truth is a property of some propositions and therefore, derivatively, a property of some sentences. Which propositions? The true ones! Which sentences? The ones that express true propositions! The proposal that we can't say more than that is sometimes known as "deflationism" about truth. For much more, see this SEP entry .
Why are there so many different theories of truth in philosophy and does the concept of "truth" have a different meaning compared to how it is generally used by non-philosophers? "Truth" for us non-philosophers seems to denote that which is absolutely incontrovertible and not open to debate. As an example, for non-philosophers, it is the truth that JFK was shot on November 22, 1963; it is debatable as to exactly WHO shot him and HOW but there is no denying he was shot that day. So do philosophers agree that it is the truth that JFK was shot on that day or is even that open to interpretation using the multiple theories of truth out there and what does that even mean?
Perhaps so many philosophical theories of truth exist because the concept of truth is central and fundamental and because philosophers have been discussing it for such a long time. See the SEP entry on truth for a survey of various theories. As for non-philosophers, I doubt that they're as united in their view of truth as you suggest, and I doubt that they're united around the conception of truth that you proposed: "that which is absolutely incontrovertible and not open to debate." I've met many non-philosophers who claim that both sides in a debate can have the true answer to the precise issue being debated: my side of the debate can be true (for me), while your side can be true (for you). I don't accept their claim, but it certainly seems to be popular. And given how strange human beings often are, few if any statements are going to be "absolutely incontrovertible" if that means "beyond any possible controversy." If, instead, it means "not rationally deniable," then the controversy will...
who decides what is "true"? What if I believe that it's TRUE that Santa Claus exists? Wouldn't it be "true for me"?
I'm not sure how to interpret the quotation marks in your first question; I'll assume they're inessential. Who decides what's true? No one, as far as I can see. One can recognize what's true, discover what's true, conclude that such-and-such is true, etc. But I don't think any of that amounts to deciding what's true. I'm not sure that even the president genuinely decides that it's true that so-and-so is pardoned; I think he decides to declare that so-and-so is pardoned, and his declaration then makes it true that so-and-so is pardoned. But he doesn't decide that his declaration makes it true. I'm not sure how to interpret the capitalization in your second question; I'll assume it's inessential. If you believe that Santa Claus exists, then as far as you're concerned Santa Claus exists. If that's what you mean by "true for me," then it's just another way of saying that you believe that Santa Claus exists, which of course doesn't make your belief true. If it did, then the concept of a false...
What is the the truth value, if they have one, of propositions whose subject do not exist? "The current king of France is bald" is the famous example. Is that true or false, or neither? I have a hard time understanding how the current king of France can be neither bald nor not bald, even though I have no trouble understanding that there is no current king of France.
Philosophers have given various answers to questions like yours. See, for example, this SEP entry . Here's one approach: "The current king of France is bald" is false because it implies the existence of a current king of France when in fact there isn't one. "The current king of France is not bald" is likewise false if it's construed as implying the existence of a current king of France (and asserting of him that he's not bald). On a possible but perhaps less likely interpretation, the second quoted sentence is simply the wide-scope negation of the first quoted sentence: i.e., "It's false that the current king of France is bald." On that interpretation, the second quoted sentence comes out true since it simply asserts that the first quoted sentence is false. On neither interpretation is anyone neither bald nor not bald, so that particular claim of classical logic -- everything is either bald or not bald -- is preserved.