Thank you for the argument for that claim, but your reasons for it do not particularly interest me. Wow. How very philosophical. We philosophers aren't interested in each other's reasons, after all. Now, am I supposed to be interested in the reasons you're giving for your claims? I've given a numbered-step argument for a claim about S, in particular, that you've been denying, viz. (32). You've responded by referring me to work that you say bears on a sentence that you say is "like" S. I'm not asking you to take my say-so. If (32) is false, then there's a mistake in my (1)-(8) or (24)-(32). Surely a professional logician can tell us what it is. You, Richard, claim to have established something by your (24)-(28), but your (24) and (25) both lack justification: (24) If (V) is a sentence-type, then no token of (V) expresses a proposition. (No token of a meaningless sentence expresses a proposition.) The justification you provide simply doesn't justify (24). You haven't...

Paracomplete theories, which are perhaps the most popular these days (though I do not myself incline to them) would reject (2), (10), and (16). There are many other choice points as well. Yeah, yeah. There are also theories that (claim to) reject (7), (13), and (22). Are we to think that those moves are even remotely plausible? Maybe they're plausible and not plausible, or neither? Perhaps you mean something like... No, I mean exactly this: (S) Either S is meaningless, or else S is false. (24) S is meaningless. [Repetition of (8), already established] (25) Either S is meaningless, or else S is false. [From (24) by disjunction introduction] (26) If S is a sentence-type, then S is a meaningful sentence-type or S is a meaningless sentence-type. [If P, then (P & Q) or (P & not Q).] (27) If S is a meaningful sentence-type, then (f) the token of it labeled "S" above is meaningful. (28) Not (f). [From (24)] (29) If S is a sentence-type, then S is a meaningless sentence-type. [From...

Okay, I'll defend my main claims in detail. Following Charles Parsons, you offered the following Strengthened Liar sentence: (S) Either S is meaningless, or else S is false. I claimed, and still claim, that S is meaningless. Reasoning: (1) If S is meaningful, then (a) S expresses the proposition that: Either S is meaningless or else S is false. [What else could S express if it were meaningful?] (2) If (a), then (b) S is true or S is false. [Bivalence for propositions] (3) If S is meaningful, then (b). [From (1), (2)] (4) If S is true, then S is true and not true. [Strengthened Liar reasoning] (5) If S is false, then S is true and not true. [Strengthened Liar reasoning] (6) If (b), then S is true and not true. [From (4), (5)] (7) Not (b). [From (6) by contradiction] (8) S is meaningless (i.e., not meaningful). [From (3), (7)] Before you say that (8) commits me to S by disjunction introduction, recall that I distinguish tokens from types. What (8) commits me to is the meaningful and...

Yes, those were my words. But the argument I was attributing to you...was NOT supposed to be: If (S) is meaningless, then "(S) is false" is meaningless. Then you can see why I was misled by what you actually wrote. In any case, the argument you say you meant to attribute to me contains a premise I deny, namely, that the first disjunct in (S) is "clearly meaningful." I've been claiming that (S) is meaningless, and I deny that any part of (S) says that (S) is meaningless, just as I deny that the sentence "This sentence is meaningless" (or any part of it) says of itself that it's meaningless. I understand that you wish to resist the claim that the conjunction of those two things (which happens to be (T) itself) ... You know I deny the claim in parentheses. Every conjunction has truth-conditions, but (T) has no truth-conditions. Neither do "dog" and "cat," and we don't produce a conjunction by writing an ampersand between those two inscriptions. The answer cannot just be, "Well,...

This is turning out to be an easy way of upping our response-counts! Surely I can name that sentence (S) if I so choose? I wouldn't say "surely." (After all, in bygone days we thought "Surely there's a set corresponding to any well-defined predicate we choose.") It may turn out that in this case, on pain of contradiction, the name attaches only to the token and not to the type. ...if you allow that "(S) is false" is false if (S) is meaningless... I trust that you too allow it -- indeed, that you insist on it. ...then it is hard to see why one would ever regard (S) as meaningless: It is a disjunction of meaningful disjuncts. Here you're simply repeating the claim I've been denying. (Furthermore, I don't see what how the antecedent of your conditional supports the consequent.) That, not the reasoning you took me to be attributing to you, is why I was assuming you would deny that "(S) is false" is meaningful. The reasoning I took you to be attributing to me is the...

Thanks, Richard, for your replies. Nice colloquy we're having. I hope anyone else is interested! Is there or is there not a sentence that is the disjunction of (S') and the sentence "(S) is false"? There is, and we can token it, but not by way of the sentence-token that you labeled "(S)" in your example. That's been my point all along: two type-identical sentence-tokens can be such that one is meaningful and the other isn't. The context in which a sentence-token is uttered can deprive it of propositional content. I say that's not surprising given other things we know about language. It won't do to respond "But I'm talking only about the syntax !" because you can't generate a liar paradox without assuming things about the truth-conditions of particular strings of words. Presumably you would also regard the sentence "(S) is false" as itself meaningless, on the ground that (S) is ... Goodness, no! That would be terrible reasoning. To say of a meaningless sentence-token that it's...

Me too, but that was my point: Despite appearances, (S'), which I endorse, isn't the first disjunct in (S). Similarly, despite appearances, the Epimenides sentence doesn't assert of itself that it's false. It follows that the meaningfulness of a sentence-token depends on more than the string of words it contains, but that result isn't surprising in light of other things we know about language.

PLEASE NOTE: Professor Maitzen's responses here and below were originally offered in colloquy with Professor Heck, who has since chosen to remove his contributions. [Alexander George on 6/6/2014.] But then it is a simple step of disjunction introduction to (S) itself. This simple step works only if (S) is the disjunction of (S') and "(S) is false," each of which disjuncts is meaningful. But if (S) is meaningless, then (S) isn't the disjunction of two meaningful disjuncts, and in particular it's not the disjunction of (S') and "(S) is false." I agree that this response to the Strengthened Liar implies that the meaningfulness of a sentence-token won't always be facially obvious. That implication seems less dire than the implications of some other responses.

I think you're right to suspect that the Liar (or Epimenides) sentence, "This sentence is false," is meaningless, i.e., that the sentence fails to express a proposition. But I wouldn't say that the sentence is meaningless because it's self-contradictory, like the sentence "God exists and doesn't exist." The latter sentence is surely false , in which case the sentence expresses a (false) proposition and hence isn't meaningless. If the Liar sentence is meaningless, then it doesn't assert of itself that it's false (because it doesn't assert anything), and therefore one of the premises used to generate the Liar paradox is false. Some philosophers have said that the Strengthened Liar sentence, "This sentence is not true," blocks such a solution to the paradox, on the grounds that a meaningless sentence is not true . The proper reply, I think, is to agree that a meaningless sentence is not true but to deny that the Strengthened Liar sentence asserts of itself that it's not true (again, on the...

You've asked a terrific question! I wish I were more qualified to venture an answer to it. As you suggest, a sound direct proof of a theorem shows that the theorem must be true, in the broadest possible sense of "must." But a sound indirect proof shows the same thing. The difference, if any, seems purely psychological: some people find one proof psychologically more satisfying than the other. My sense is that some philosophers of math take this psychological difference very seriously and propose far-reaching revisions to classical math on the basis of it. You might take a look at the SEP entry on intutionism in the philosophy of math , particularly the discussion of constructive and nonconstructive proofs. The entry includes other helpful links and references too.

You seem to be asking about the legality of switching or declining to switch, in which case your question is best answered by a lawyer rather than a philosopher of law. I'm not sure, but the answer may depend on the jurisdiction. It may also matter whether the person in a position to switch the trolley is legally authorized to be in that position or is, instead, a trespasser or intruder. I'm not suggesting that the answer provided by the law is totally irrelevant to the morally right answer. The law on this issue, if there is any, may reveal the moral attitude that we currently take toward it, which is relevant to some extent.

You asked, "Have you found that philosophy leads to more skepticism and knowing nothing rather than clarification?" It may be that you didn't sacrifice any knowledge that you previously had. Your philosophical reflection may have revealed to you that you didn't in fact know what you took yourself to know before you engaged in it. Maybe you had confident beliefs about whom you ought to vote for, etc., and even the confident belief that you knew whom you ought to vote for, etc. Examining your grounds for those beliefs caused you to lose confidence in them. In Plato's dialogues, Socrates is portrayed as frequently showing people that they didn't in fact know what they confidently took themselves to know. That's an important discovery one can make about oneself. Even if your philosophical reflection has made you question some of your previously held beliefs, it doesn't follow that you ought to become a wholesale skeptic. Philosophical reflection should include scrutinizing the grounds for...

I can't resist piping up to defend Rawls's Veil of Ignorance. In A Theory of Justice , Rawls anticipates and rebuts the questioner's objection. The deliberators behind the Veil of Ignorance are choosing the most general principles of justice that will govern their society, and hence they have no basis for the specific prediction that a given principle will make "90% of people happy and 10% utterly miserable": as Rawls says, behind the Veil of Ignorance such numerical estimates "are at best extremely insecure" (p. 154). Given that insecurity, Rawls argues that it would be irrational for you to risk being among the utterly miserable, particularly if your gain in happiness (compared to what you'd experience in a less unequal society) is small compared to what you'd lose if you end up among the utterly miserable. His argument may not be conclusive, but I don't think it's as easily dismissed as the questioner suggests.

You seem to suggest that all questions, or maybe all questions worth trying to answer, might be answerable (at least in principle) by experimentation and calculation alone. But I can't see how they could be. Let Q1 be any question. Now consider the normative question, Q2, "Is Q1 worth trying to answer?" I can't see how Q2 could possibly be answered by experimentation and calculation alone. So there will always be questions of that normative kind left over. You might reply that those leftover questions aren't worth trying to answer, but that reply would itself be a normative claim that we couldn't assess using experimentation and calculation alone. It may also be that Gödel's incompleteness theorems imply that the answers to at least some questions will never yield to experimentation and calculation.

I responded to somewhat similar skeptical worries about personal identity in my reply to Question 4958 . You might have a look there. To respond to your specific claims here: (1) Even if we grant that you're "basically a combination of cells created by DNA instructions [that] react to stimuli," surely that's not all you are. In a petri dish we can grow a combination of cells created by DNA instructions that react to stimuli, but it won't submit a question to AskPhilosophers. Not all combinations of cells -- again, assuming that's what you are -- have equally impressive capacities. (2) Even if "everything [you] say, believe, and do is based on [your] genetic make-up and environment," surely that not all it's based on. You submitted a question to AskPhilosophers at least partly based on your desire to get an answer to it and your belief that this website is one place to go; there's no reason to think you would've done so without any such desire or belief. ...

You might also look into the work of philosopher Eli Hirsch (Brandeis University), who argues that various disagreements in ontology, perhaps including the one you mentioned, are "merely verbal" disagreements.

If she had reasons to believe, it would not be faith that she had but knowledge. I respectfully reject the implicit reasoning in Prof. Marino's claim. Someone's having reasons to believe may make her belief rational or epistemically justified, but her belief is knowledge only if her belief is true , and its truth doesn't follow from her having reasons to believe. [A]s human beings we still have to decide whether or not [to] believe in what falls outside the bounds of reason. Does what falls outside the bounds of reason also fall entirely within the bounds of reason? If no, why not? If yes, then how can anyone understand the statement of Prof. Marino's that I just quoted?

It's a good idea to consult the SEP for discussion of these questions and for citations to various published answers. Continue to do so. I'd question, however, whether "most philosophers today" reject the analytic/synthetic distinction. According to the recent PhilPapers survey, 64.9% of "target faculty" either "accept or lean toward" accepting the distinction (see this link ). Reports of its demise would appear to be exaggerated.