• EricH
    608
    If it doesn't make sense in this case, why not?Srap Tasmaner

    I'm repeating myself, but I'll try again. When I use the words "truth" or "true" I am using them in the same sense as used in a court of law. A sentence is true if and only if it describes a fact/event. A sentence is false if it describes an fact/event that could have happened but did not.

    The cat is on the mat. This sentence is either true or false depending on where the cat happens to be physically located.

    The cat undermined indecisiveness Under the standard/common'/dictionary definitions of the words, this sentence is neither true nor false since it does not assert anything that could be a fact/event.

    A sentence has to make a potentially factual assertion in order to take a truth value.

    This sentence is false. <-- This sentence just to the left does not make a factual assertion. It does not take a truth value.
    The cat is on the mat. <-- This sentence just to the left makes a factual assertion. It is either ture or false.

    I hope this helps I don't know if I can make it any clearer.
  • 3017amen
    3.1k
    I have not read through the entire thread, so apologies if this point has already been made.

    Maybe I'm being naive or missing the point, but I use the word "truth" pretty much as it is used in a court of law. When you swear to tell the truth, the whole truth, and nothing but the truth? Basically you are saying that your words and sentences will - to the best of your ability - describe facts. I'm not super knowledgeable about all the different schools of philosophy, but I'm pretty certain that this is some variation of the Correspondence Theory.

    So when you say "This sentence is false"? In order for for this sentence to have any meaning, the pronoun "this" must refer to some statement that makes a factual assertion about reality/existence/the universe/etc. In this case, no such assertion is being made, hence the sentence is meaningless and cannot take a truth value.
    EricH

    I would say it's advisable to read the thread, hence:

    Mathematician and logician Kurt Godel (and Alan Turing/Turing machine and Bertrand Russell--you can Google that if you will) explored the concepts of infinity versus finitude as it relates to mathematics (deduction).

    Without getting into the technical details (which we can if you want) Godel parced the relationship between the description of mathematics and mathematics itself. Basically, he was known to have labeled mathematical propositions combining a sequence of propositions into corresponding natural numbers that form associated labels. Logical operations about mathematics were made to correspond to mathematical operations themselves. The idea linked the self-referential concept of Godel's proof by identifying the subject with the object.

    Accordingly, self-referential paradoxes is the appropriate analogy. As mentioned in the OP, the liar's paradox is an unresolved paradox that of course is self referential. It's undecidable, and it's incomplete. And it's based upon a priori logico deductive reasoning.

    BTW, as you alluded, this is philosophy; not the law of contracts.
  • Nagase
    197


    You said that the sentence "This sentence is not false" was meaningless. I then asked, supposing it meaningless, why it is meaningless. Notice that there is an important respect in which it differs from your other examples of meaningless sentences: whereas your other examples all display violations of thematic relations (and, if you like generative grammar, theta roles), "This sentence is not true" does not display such violation. So there must be some other reason why it is meaningless. You then say that it does not describe a state of affairs. Well, the sentence "the cat is on the mat and the cat is not on the mat" also does not describe a possible state of affairs, yet it is clearly meaningful---in fact, it is false. So what is the difference between that sentence and the liar?
  • Nagase
    197


    I take it that there are two ways of interpreting your objection to the use of formal systems. One is a ban on the significance of formal systems tout court---they are merely a game. The other is a ban on formal systems as tools for interpreting ordinary practices. That is, perhaps formal systems have their uses in sharpening our concepts or in helping to predict a given phenomenon, or whatever, but not in understanding ordinary practices. I will consider first the stronger reading, which is I think more easily disposed of, and then I will offer some remarks as to why I think you're mistaken even on the second reading.

    The basic thrust of my argument in favor of formal models is this. The world is complex, and to understand its structure in its entirety is a hopeless endeavor. Fortunately, science has provided us with a very useful paradigm for making progress, namely to understand one bit at a time. Think of Galileo's inclined plane, here. By abstracting away from complexities such as friction, etc., he was able to isolate the effects of gravity on the fall of objects. Similarly, by abstracting away from, say, the pragmatic aspect of communication, we may usefully isolate important aspects of a given concept. Now, one may say that this is only possible in physics because physical phenomena are much simpler. I think this is a misconception produced by the tremendous success of idealization in physics; in truth, physical phenomena are extremely messy, and it is only our idealization practices that introduce some order into this chaos (cf. the work of Nancy Cartwright in this regard).

    Hence, formal models can be extremely useful in understanding a concept, if only because their simplicity provides a good testing field for our hypotheses. As Timothy Williamson says:

    Philosophy can never be reduced to mathematics. But we can often produce mathematical models of fragments of philosophy and, when we can, we should. No doubt the models usually involve wild idealizations. It is still progress if we can agree what consequences an idea has in one very simple case. Many ideas in philosophy do not withstand even that very elementary scrutiny, because the attempt to construct a non-trivial model reveals a hidden structural incoherence in the idea itself. By the same token, an idea that does not collapse in a toy model has at least something going for it. Once we have an unrealistic model, we can start worrying how to construct less unrealistic models. ("Must Do Better")

    The case of the concept of truth is one of the examples adduced by Williamson to illustrate this claim. As he puts it earlier in the essay:

    Another example: Far more is known in 2007 about truth than was known in 1957, as a result of technical work by philosophical and mathematical logicians such as Saul Kripke, Solomon Feferman, Anil Gupta, Vann McGee, Volker Halbach, and many others on how close a predicate in a language can come to satisfying a full disquotational schema for that very language without incurring semantic paradoxes. Their results have significant and complex implications, not yet fully absorbed, for current debates concerning deflationism and minimalism about truth (see Halbach (2001) for a recent example). One clear lesson is that claims about truth need to be formulated with extreme precision, not out of knee-jerk pedantry but because in practice correct general claims about truth often turn out to differ so subtly from provably incorrect claims that arguing in impressionistic terms is a hopelessly unreliable method. Unfortunately, much philosophical discussion of truth is still conducted in a programmatic, vague, and technically uninformed spirit whose products inspire little confidence. (ibid.)

    So I hope it is clear that formal methods have their place in understanding the concept of truth. Let us then turn to the question of whether formal methods have their place in understanding our ordinary practices. Again, I think the answer is yes. Specifically, I think it's highly plausible that ordinary reasoning conforms to the Cut and Contraction rules. Obviously, this does not mean that, when people reason, they consciously employ the formalism of the sequent calculus! But it does mean that this formalism aptly describes their practices.

    In order to understand how this can be so, it is useful to recall here Sellars's distinction between pattern-governed behavior and rule-obeying behavior. Both types of behavior occur because of rules, but only the latter occurs because the agent has a conscious representation of the rule. Here is one of Sellars's examples of pattern-governed behavior that is not rule-obeying behavior: the dance of bees. In order to indicate the position of a given object of interest, bees developed a complicated dance that codifies this direction for the other bees. This gives rise to a norm of correctness for the dance: the dance is correct if it indeed points in the direction of the object. If the bee performs the dance, and the dance leads nowhere, clearly something has gone wrong. In Millikan's helpful terminology, that is because it is the proper function of the dance to indicate the object, so that, if it is not so indicating, it is failing its purpose. Notice that this does not require anything spooky, just natural selection, and notice also that although we can clearly describe the dance in normative terms by employing a normative vocabulary, obviously the bees can do no such thing (the question of whether or not the bees must have a conceptual representation of space in order to perform such a dance is a separate and more difficult question. For a surprisingly good case for answering it in the affirmative, cf. Carruthers, "Invertebrate concepts confront the generality constraint (and win)").

    So my claim is that our ordinary reasoning practices are, in this respect at least, much like the bee dance. They are pattern-governed behavior, that is, a behavior that happens because it has been selectively reinforced (either through natural selection, if such reasoning is innately specified, or through socialization; here, game theory can provide some nice formal models of how this can happen without a conscious effort by the agents), but not because the agents are aware of the rules governing their behavior. These rules are, however, implicit in our practices, and the role of logical vocabulary is (among other things) to make them explicit, since it is only by making them explicit that they become subject to rational evaluation.
  • Srap Tasmaner
    4.9k


    These glimpses into your views of philosophy -- or at least glimpses of how many contemporary academic philosophers view their work, perhaps you among them -- are very helpful.

    If philosophy is to be not just a sort of maternity ward for the sciences, and not their handmaiden, but itself a science (if not the queen), then it's the science of -- ? Concepts?
  • Srap Tasmaner
    4.9k


    You've addressed this sort of question at length, but doesn't this strike you as an odd thing to say:

    Far more is known in 2007 about truth than was known in 1957 — Williamson

    I don't think my eyebrows would have shot up if he had said, 'Far more is known in 2007 about modeling truth in certain widely used formal systems than was known in 1957.'

    After all, here we are discussing a book published five or six years after that pronouncement, which proposes that the concept of truth Williamson refers to is inconsistent and ought to be scrapped.

    That needn't give one pause, buy can we say there is more to philosophy being a science than philosophers proceeding as if it is? Is there a pudding you could point to in which we would find the proof?
  • Nagase
    197


    I'm happy that my posts have been helpful, though I'm not too sure if I'm representative of academic philosophy---I'm finishing my PhD in a third-world university, after all, with little or no contact with the big players.

    As for your assessment of Williamson's claim, I personally think Scharp's books is exemplary of the trend he was discussing. Knowledge about a concept can include knowledge that a concept is inconsistent, after all! And Scharp's discussion is thoroughly informed by the relevant technical literature, so much that Ripley can actually point out that, according to his own light, perhaps it is not the concept of truth that is inconsistent, but the concept of derivability or validity. Notice that Ripley's position, according to which the problem is not with the concept of truth but with our reasoning practices would be difficult even to formulate, let alone emerge as a serious contender in this debate were it not for the formalism of the sequent calculus. So this whole debate surrounding Scharp's book can be considering the pudding, if you will.

    If that's not enough, I think there are at least two more interesting formal results that should be considered in this debate (and that, given Williamson's reference to Halbach, it is plausible to hold that it is what he had in mind). After Tarski formulated his T-schema (itself a formal achievement!), radical deflationism appeared to be almost inevitable. For suppose that there is something substantive about the predicate "... is true". Then, presumably, it contributes something to the truth-conditions of the sentences in which it appears. But, by Tarski's T-schema, for any sentence S, "S" is true iff S, whence the truth conditions of "'S' is true" are the same of S, so the predicate can't contribute anything to the truth conditions of the sentences in which it appears. By modus tollens, there is nothing substantive about truth.

    That would appear to be the end of the story, but Tarski and Gödel proved further that it is impossible to add a truth-predicate to a theory and preserve consistency. This seems weird: if truth is not substantive, how can the addition of a truth predicate generate a contradiction? Anyway, perhaps there is something funny about the interaction of the truth-predicate with other formal devices, so here is a proposal: just take as many instances of the T-schema as are consistent, and this will fix at least the extension of the predicate. This proposal was one of the first versions of minimalism: the truth predicate is entirely exhaustible by the maximally consistent set of instances of the T-schema. Unfortunately, Vann McGee showed that there are many maximally consistent sets of instances of the T-schema, so this procedure will not uniquely pin down the truth predicate.

    At the same time, there is a growing suspicion that perhaps there is something substantive, after all, to the truth predicate. This suspicion is buttressed by the following formal result: even adding a truth-predicate that obey very minimal compositional principles to a theory is sufficient to obtain a stronger theory. That is, if the truth predicate were indeed non-substantial, we would expect that its addition to a theory would not result in new theorems being proved. But that is precisely what happens. In particular, the consistency of the old theory can be proved in the new theory. So it does seem that there is something to truth, after all. Part of the problem seems to be that the truth predicate is not exhausted by the T-schema, but can also function as a device for generalization (i.e. "Everything she said is true"), which can only be eliminated through infinitary resources (an infinite disjunction "Either she said P and P, or she said Q and Q, etc."---though do note that it's not entirely clear that even this disjunction exhausts the truth-predicate in its generalization function).

    So at least two prima facie plausible positions (minimalism and a certain naive deflationism) have been refuted by formal considerations. As a result, we have gained a deeper understanding of the truth-predicate and how to handle it. We know now that it is not just an innocuous predicate and that it is tangled up with all sorts logical considerations. Of course, that is not to say that all questions have been settled, very far from it (there are still minimalists and deflationists around, after all). But it is to say that we have a deeper understand of what is in question when discussing truth.
  • Nagase
    197


    Incidentally, I don't think boundary policing ("Is philosophy a science?") is much helpful. Philosophy is whatever is practiced at philosophy departments. In many cases, this involves a lot of interdisciplinary work (with cognitive scientists, linguists, physicists, medical doctors, etc. etc.), so that the boundaries are not very sharp. In other cases, it is more abstract, perhaps more reflective, and so clearly more distant from whatever it is we consider to be science. But good philosophy is good philosophy, and I don't see much value in pushing one conception of what philosophy should be over others.
  • Janus
    16.2k
    The sentence itself, is in fact true, because it's a sentence.3017amen

    A sentence is just a string of words; how could a string of words be true or false? I think it is more in keeping with what is commonly meant to say that sentences express propositions, and that it is propositions which may be true or false. I say this because a propositions can be expressed in many different ways (sentences).

    Sounds kind of like Kantian things-in-themselves... .3017amen

    I'm not seeing the connection.
  • 3017amen
    3.1k
    sentence is just a string of words; how could a string of words be true or false? I think it is more in keeping with what is commonly meant to say that sentences express propositions, and that it is propositions which may be true or false. I say this because a propositions can be expressed in many different ways (sentences).Janus

    Because it describes something, as in declarative sentences. And of course in this instance, if it makes a declaration about itself, it has the potential to become an unresolved paradox.. The liars paradox in neither true nor false. It's based on a priori and logical deductive reasoning. Kind of like mathematics (Godel/Heisenberg etc.).

    One of the downsides of so-called pure objective reasoning...
  • Janus
    16.2k
    The liars paradox in neither true nor false.3017amen

    I agree with that. "This sentence is false" becomes problematic only if we reason that it follows that it must be true that it is false, or in other words that its negation must be true. If we do that then we become stuck in a vicious circle of contradiction; if it is true then it is false, if it is false it is true,,,

    But if we just ignore its truth claim in the first instance, seeing that it refers to no possible state of affairs which could make it true or false; then we simply step aside and the whole absurd logical machinery rolls past without touching us.

    It's not a problem with "objective reasoning"; because this so-called proposition has no coherent object.
  • 3017amen
    3.1k
    It's not a problem with "objective reasoning"; because this so-called proposition has no coherent object.Janus

    I don't think so Janus, hence:

    Socrates: What Plato is about to say is false.
    Plato: Socrates has just spoken truly.
  • Janus
    16.2k
    Firstly you can't reasonably claim that what someone is about to say is false because you don't know what they are going to say, that is there is as yet no coherent object your statement refers to. But putting that objection aside for the sake of argument, the problem is that there is no coherent object to assess their truth in either of these statements.

    Consider this: Socrates: What Plato said is false
    Plato: Socrates has spoken truly

    In this case there could be a coherent object in the statement of Plato's being referred to (which we have not seen) and we are not able to make any assessment as to whether both are correct in their agreement that the statement was false until we know what that statement is.
  • Srap Tasmaner
    4.9k
    if we just ignore its truth claim in the first instance, seeing that it refers to no possible state of affairs which could make it true or false; then we simply step aside and the whole absurd logical machinery rolls past without touching us.Janus

    This is next door to the view I've come to.

    Certainly the Liar appears, or attempts, or purports to predicate falsehood of itself. But there is no way for it to predicate falsehood of itself without also predicating truth of itself -- an instance of predicating Fx and ~Fx at the same time in the same sense. Not only is that a contradiction -- which just leads us back around the loop if we're only concerned with truth value -- it's just not predication. So I think we view the Liar as infelicitous, a misfire, an attempt at predication that fails.

    I keep thinking that the heavy logico-semantic approaches take the Liar at its word -- that because it purports to have predicated falsehood of itself, that's what it has done.

    That leaves lots to think about, because this way of looking at it doesn't exactly explain the Liar -- on this view, explaining exactly how and why it fails to say what it's trying to. It can't be said -- and I'd like a cleaner way of saying that too -- so we really already know that it's going to fail, but there are different ways of failing to do something impossible, and I'd like a clearer view of what happens here.
  • Srap Tasmaner
    4.9k


    Thanks for indulging my questions -- I hope it's also of value to you to formulate your views for us to read. (I have some conflicting allegiances, so it is indeed helpful to get another's perspective.)
  • Janus
    16.2k
    :up:

    I adhere to a correspondence account (not theory, mind) of truth. I see Tarski's T-sentence as a minimalist presentation of the logic of correspondence. I don't believe we can analyze and explain just how correspondence works (hence no theory) but we know it does because all our practices are founded on it. I tend to think of the logic of truth as being the other face of the logic of actuality.

    If we can't say just how truth works, then it would seem to follow that we cannot precisely explain how cases like the Liar fail. We can see that there is no state of affairs to which they refer, though, and realize that there is something missing that is not missing form ordinary propositions. I am satisfied with that and prefer to turn to other things. I realize that others may not be so satisfied, though. :smile:
  • Srap Tasmaner
    4.9k
    others may not be so satisfied, thoughJanus

    Yeah that would be me. For instance, I'm not convinced that '... is true' is a predicate at all, so the scheme I presented there is only a nod toward what's really happening. Lots to think about.
  • Isaac
    10.3k
    I take it that there are two ways of interpreting your objection to the use of formal systems. One is a ban on the significance of formal systems tout court---they are merely a game. The other is a ban on formal systems as tools for interpreting ordinary practices.Nagase

    Neither really, just that (as you later allude to) as models they need to have something to hook them back to the thing they're modelling. In models of physics, for example, that's experimental hypothesis testing. I have no objection to models in principle (I'm pretty much a model-dependent realist so models are my building blocks of reality - quite important). I also have a great deal of sympathy for the work of Nancy Cartwright as a consequence. It's just that logical models of things like truth make what, to me, is a massive assumption about the way language works in psychology which is largely unsupported by the evidence in that field.

    When we assign a truth value to a proposition, the assumption goes, we're performing some analysis of the syntax, the semantics of the actual proposition and the result is some binary value (true/false). But this is not what we see happening in the brain, nor do we infer it from behavioural experiments.

    When reading a sentence with a semantic mismatch "my dog is house" fro example, there are N400 elevations associated with language comprehension which do not trigger responses in higher cortices. We dismiss, or flag such sentences as being 'untrue' without recourse to any logical processing whatsoever. that a dog can't be a house i just part of what learning how to use the words 'dog' and 'house' entail, it's has nothing to do with the logical truth value of the proposition - these processes are virtually identical to those seen with syntactic mismatches "my dog is quietly".

    Semantic mismatches produce the same neural responses here regardless of the truth of the proposition being assessed.

    There was a key study done in Germany a few years ago which presented subjects with opposing groups of sentences to assess - true/matched "Africa is a continent"; true/mismatched "Saturn is not a continent"; false matched "Saturn is not a planet" and false/mismatched "Africa is not a planet". What they found was that the truth evaluation method used was context dependent. Those tasked with evaluation (rather than sorting) engaged a different process despite earlier experiments showing the n400 response to sematic mismatching.

    Basically sentences which are meaningless by lack of sematic matching are processed as such prior to, and independent of their truth evaluation. "This sentence is false" doesn't strike us a odd because we don't know how to evaluate the truth condition. It strikes us as odd because there's a semantic mismatch (sentences alone aren't the sorts of things that can be false).

    Truth evaluation (as opposed to sematic mismatch assessment) is a complex process. Fluent sentences (presented in say a clear, high contrast font) are more likely to be assessed as true, even by experts in the subject of the sentence, than ones in a low contrast font. Even at expert, highly specific knowledge assessment, the linguistic aspects of the sentence (fluency, grammar, prosody, source...) play a part in truth evaluation.

    Finally, even when we arrive at a fairly uncomplicated truth-evaluation outside of pure linguistic comprehension, we find that semantic processing is embodied almost entirely. Sensory-motor, auditory, visual, olfactory, etc... are engaged in the processing of state evaluation in concepts pertaining to those relevant cortices. "this sentence is true/false" would not be processed in the same way as ""my dog is green" is true/false" because the very processing mechanism for the truth evaluation of "my dog is green" relies on the visual cortex's model of 'dog' and 'green' not as logical concepts but as exterior world states to which there is an appropriate response.

    Basically assessing the truth value of sentences is a context dependent involving syntactic and semantic assessments, socially mediated source judgements, emotional valence, and embodied response rehearsal. We're basically classifying these propositions on the basis of what we'd do about them, not on the basis of their logical coherence.

    Logical models may well be a very positive tool in some areas, I'm not trying to dismiss their utility entirely, but when dealing with something like our mental processing, they have to be indexed to what's actually happening.
  • bongo fury
    1.6k
    A sentence is just a string of words; how could a string of words be true or false?Janus

    How could a word denote an object? How could a coin have a value? How could a hammer have a purpose? How could a note be a quarter-note?

    By convention / a game of pretend.

    I think it is more in keeping with what is commonly meant to say that sentences express propositions, and that it is propositions which may be true or false.Janus

    Unnecessary platonism.
  • 3017amen
    3.1k
    Firstly you can't reasonably claim that what someone is about to say is false because you don't know what they are going to say, that is there is as yet no coherent object your statement refers to. But putting that objection aside for the sake of argument, the problem is that there is no coherent object to assess their truth in either of these statements.Janus

    Actually, you can. it's done quite often in everydayness when people banter about. Even though the direct object is not explicit, it's implied as being an indirect object.

    Perhaps more importantly, self-reference is about the knowing of the subject/person itself, and because we don't know the nature of our own existence, such paradox exists. Think of it as if there was another language that could possibly have the capacity to unpack such a paradoxical statement. As it stands, our language, being part of a temporal condition, precludes such resolution.

    Also, keep in mind that because a particular string of vocabulary is incorrect syntax for one language, it does not mean that it's incorrect for another. "Car on part" may be incorrect syntax for English, but is correct syntax for French (not to mention unusual syntax for lyrics, poetry, computer language, etc.).


    Consider this: Socrates: What Plato said is false
    Plato: Socrates has spoken truly

    In this case there could be a coherent object in the statement of Plato's being referred to (which we have not seen) and we are not able to make any assessment as to whether both are correct in their agreement that the statement was false until we know what that statement is.
    Janus

    But that's not a self-referential declaration. In that transaction, it leaves out the concept of self-reference by not using the word 'about'. Which is to say that the statement would be about someone else, the indirect object. And so all you have there is just ordinary semantics.

    But back to the OP, all this basically means is that there will always exist certain true statements that cannot be proved to be true (just like in mathematics/Gödel).
  • Janus
    16.2k
    How could a word denote an object? How could a coin have a value? How could a hammer have a purpose? How could a note be a quarter-note?

    By convention / a game of pretend.
    bongo fury

    Yes, of course, obviously the meaning of words, what they refer to, is established by convention, by praxis. How else?

    Unnecessary platonism.bongo fury

    You're misunderstanding; I am not promoting platonism. The word 'sentence', in conformity with conventional usage, can be taken to mean either "a string of words" or something like 'a statement' or 'a proposition'.

    The logic behind what I said is simple; the same proposition can be expressed in many different sentences, and when we say a sentence is true the meaning of 'sentence' as 'proposition' is the appropriate one. No platonism required.
  • Janus
    16.2k
    Actually, you can. it's done quite often in everydayness when people banter about.3017amen

    If you make a guess as to what someone will say, and claim that it will be true or false, then you have imagined a proposition which contains objective content which may be checked for its truth or falsehood.

    In other words you have not merely to claim that what someone is about to say will be true or false, but to state what you think they are about to say, and why you think it is true or false; if you are not merely playing the fool, that is.

    But back to the OP, all this basically means is that there will always exist certain true statements that cannot be proved to be true (just like in mathematics/Gödel).3017amen

    No empirical statements (propositions proper) can be proven to be true, but we can, in principle at least, check to see if they are.

    Also I think you are misusing Gödel. His Incompleteness Theorem applies only to a certain kind of arithmetic, unless I am mistaken. And even there the claim is that there are true statements, within the system, that cannot be proven from within the system. They may be proven from without though. So, the basic idea here, and anyone who understands this better than I do may correct me, is that systems of this kind will be either incomplete or inconsistent.
  • 3017amen
    3.1k
    No empirical statements (propositions proper) can be proven to be true, but we can, in principle at least, check to see if they are.

    Also I think you are misusing Gödel. His Incompleteness
    Janus

    The statements themselves are a priori just like mathematical truth's. That's why it's analogous to Gödel (Gödel did the same thing in his experiment). They are essentially a priori constructed sentences that reference themselves.
  • bongo fury
    1.6k
    Yes, of course, obviously the meaning of words, what they refer to, is established by convention, by praxis. How else?Janus

    :100: :up:

    You're misunderstanding; I am not promoting platonism.Janus

    I don't want to be the Spanish Inquisition, but you did seem to think it absurd that true and false could apply to strings of words; and while this might have been for completely other reasons than the concreteness of words, or belief in beliefs and other mental or otherwise abstract entities (propositions and states of affairs) as the only rightful subjects for such predication, such beliefs do seem rife in this thread, and they seem to me an unnecessary cause of confusion.

    The logic behind what I said is simple; the same proposition can be expressed in many different sentences, and when we say a sentence is true the meaning of 'sentence' as 'proposition' is the appropriate one. No platonism required.Janus

    By platonism I mean commitment to abstract entities, and so I would be glad to withdraw the charge (of an excess in this tendency) if it turned out you just meant to recognise a potential fuzzy set of (the "many different") sentences that were rough paraphrases of each other. Have true apply to any and all paraphrases by implication whenever they applied to one. But it seems clear you want to warn me that people round these parts believe in propositions as a separate class of entity. Well that's what I meant by "unnecessary platonism".



    Talking of paraphrase, here are some nominalist paraphrases of "this sentence is not true":

    • "this sentence fails to point its predicate at the object identified by its subject"

    • "this sentence fails to point its predicate at its subject"

    • "this sentence purports but fails to point its predicate at itself"

    Where the subject of the sentence is the phrase "this sentence", and the predicate is the remaining word string.
  • Janus
    16.2k
    But it seems clear you want to warn me that people round these parts believe in propositions as a separate class of entity. Well that's what I meant by "unnecessary platonism".bongo fury

    I wouldn't say propositions are " a separate class of entity". More modestly I would say that a proposition is the semantic content of some sentences or statement. (I write "some" to indicate that this is not to say that there are no non-propositional sentences).
  • Janus
    16.2k
    You seem to be clutching at straws. If you want to address something I've said without distorting it or changing the subject, then I'm prepared to listen.
  • Gregory
    4.7k
    I think the human mind is capable of making some kind of sense out of any sentence. I am reminded of when Paul first sang "The movement you need is on your shoulder" and added "I'll have to change that". John responded "You won't. That's the best line." It made perfect sense to him, and does for many listeners : )
  • 3017amen
    3.1k
    is that systems of this kind will be either incomplete or inconsistent.Janus

    Correct; hence:

    Amen: What Janus is about to say is false.
    Janus: Amen has just spoken truly.

    Yet, the sentences, in themselves, are coherent and complete. In other words, they are not sentence fragments lacking both subject/predicate.

    And so there will always exist certain true statements that cannot be proved to be true.

    Yet another mystery in life :snicker:
  • Razorback kitten
    111
    Surely you need only check the context in other words? So many English words are ambiguous until used in a sentence. You're just being picky.
  • bongo fury
    1.6k
    More modestly I would say that a proposition is the semantic content of some sentences or statements.Janus

    False modesty. :wink: Nowt so abstract as "semantic content".
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