Notes on "Degenerate Case" Dialetheism

 “Degenerate Case” Dialetheism

Motivation: trouble with even the most sophisticated and beautiful gappy approaches e.g. Kripke - the ‘not true’ and samesaying. Priest’s view really is better in a way. A resting place. But! Don’t get over-excited now! It’s not as if we should start to think that reality is full of contradictions or something, and look for other cases, and think of this as some kind of instructive extra special mindblowing truth - contradictory truth. As if, if you could understand this fully, that’d be the best shit. Rather, paradoxical statements are a degenerate case -

Immediate difficulty arises here: risk. The statements aren’t themselves degenerate.

Kripke’s lesson about empirical Liars is very important. (Is he the originator of the point? I wonder. It’s not as if this is even widely isolated as a potential contribution afaick.)

What is really the difference between this view and that of Priest et. al.? Perhaps it lies largely in a difference of opinion about how much this should influence logical theory, how front-and-centre it should be in our conception of logic. I think in many ways it is perfectly good to continue with bivalent logic even if accepting dialetheism about Liar-like paradoxical statements. Why does it seem such a threat? Well, it has to do with the universality pretensions - aspirations, I should say - of logic. It obviously is no good for logic mainly to issue in truths of the form ‘usually, …’ or something like that. But that is not the only way to view it - we can still say that bivalent logic is absolutely correct for all non-paradoxical statements. And yes, when we ascribe truth we run a risk of paradox, as Kripke emphasises. 

Even though we do risk dialetheia, and 

I talk to my students about it and make it natural to motivate LP: If you’re a dialetheist you are pushed to do nonclassical logic, since 

I agree that Priest’s logic is more generally correct because it handles paradoxical cases - i.e. we do not have to stop applying it and forming our beliefs in accord with it in response to paradox, it’s idiot-proof w.r.t. paradox. 

But modus ponens fails! Etc.

Look, it’s technically correct that LP is more general, and that is fascinating- some logical principles are paradox-proof and others aren’t. But at the end of the day, there is a lot to be said for paying attention to classical logic. Because paradox so rarely actually fucks us up. 

((Try to think about how one might actually be led astray “applying classical logic” when in fact there’s a paradox. How does the risk show up exactly.))

((Could there be a kind of interesting contingency to this view I’m developing? Paradox rarely fucks us. Could we imagine a hypothetical scenario in which the risk is a big deal and for natural reasons we often fall into paradox? That could be very interesting.)

OK MAYBE HAVE SOMETHIGN

OK, 

But, if you apply LP to your beliefs and that includes paradoxical ones, you will still have more false (but also true!) beliefs by inferring from paradoxical propositions. You’re sort of still fucked, in the sense that you might have paradoxical beliefs. But full credit, it won’t give you plain false (i.e. not also true) ones unless you have plain false ones going in to the inference.

(What is K3 like?)

Relate to notions of ‘the correct logic’.

Let’s get down to brass tacks.

Do we not even tell people about modus ponens because that’s proven wrong by paradoxical examples? Of course not.

It’’s not some embarrassing oversight that bivalent classical logic is central in the logic curriculum. 

What am I really arguing here? Well, looks like a bunch of empirical normative stuff, what am I doing? But really i’m doing the conceptual work of showing how accepting certain things i.e. dialetheism by the letter does not mean ‘abandoning classical logic’ in the full sense of chucking it out or regarding it as discredited. It’s just realising a peripheral limitation. 

Can A Dialetheist Endorse Classical Logic Without Being Pushed to Believe Everything?

RNs

Ripley & someone review of Spandrels in Mind 

A spandrel is an unintended by-product of a design choice.

But I don’t want to lose the framing of: Liar propositions are there to be asserted, whatever we do. 

This part I think I want to go along with but will have to look into and think critically about the ‘merely semantic’ bit. 

Beall holds dialetheia to be ‘merely semantic’ (p. 16). In other words, expressions not involving the truth predicate belong to a part of our language that is fully classical. The only dialetheia countenanced by the view are side effects of the introduction of semantic vocabulary: paradoxes and other ‘ungrounded’ sentences. For this reason, Beall regards his view as a modest brand of dialetheism.

Abf

Degenerate Case Dialetheism - Beall’s view may be, or be close to, an instance of this. But we can get to the dialetheism not by Beall’s particular route in detail - his ttruth setup

The idea of ‘spandrels’ seems to motivate the choice of a logic as close to classical as possible while holding to non-triviality; and while it is unknown just how close is as close as possible, we can get considerably closer than BXTT. (All of the above-mentioned axioms and rules are classically valid.) Spandrels would be improved by a discussion of the known non-triviality-preserving principles that can be added to BXTT, and arguments as to why they should not be added, if indeed they should not.

This idea of getting as close as possible to classical logic is very interesting. And I think my emerging suspicion about the Liar and my view of what it means makes me think this is wrong-headed. It would be interesting to try to work this through.

What I mean is that I have a hunch of the following kind: LP presented semantically is faithful to the phenomenon and there’s no reason to think it’s wrong except wanting more classical stuff to come out valid without getting triviality/explosion.

One way to strengthen this would be to explain how the model theory and designated value choice gets things right.

((Beginning to think about this just now. I do wonder about the idea that if one disjunct of a disjunction is just-true but the other is both true and false, the disjunction is just true. But I think it may be good.))

Another way is to look for cases where some dialetheist-endorsed logic goes beyond LP and try to explain why, from the dialetheist perspective, it shouldn’t. 

I’m just thinking now: it seems natural to think that in many cases where we want to apply logic, we want just-true conclusions. But who cares if we needed some dialethia to get to them? The perspective is: arguments are just-truth machines, but if we can fuel them with a mix of just-true and both premises as well as all just-true premises, all to the good, no reason not to use this degenerate fuel if it works. 

(‘But the classical machine has more validities!’ Yes but sometimes we might want our deduction to be paradox risk proof, in the sense that our conclusion is still just-true even if some of our true premises were also false.)

The logics I’m aware of that we get by having 3-valued semantics and designated values all make double mention of the designated value(s): when talking about the premises, and when talking about the conclusion. So we can make a different choice each time. And that is the natural thing to do on this picture:

An argument is valid iff every model M which makes each premise either 1 or X makes the conclusion 1.



***

It is remarkable how quickly we tend to be ready to move from dialetheism to the revision of logic. Perhaps part of this is that we are so aware of it being a radical move, that radicalness is so salient, that revising logic no longer shows up as a big thing because it is side by side now with dialetheism. All bets are off in a sense.

The decisive move in the conjuring trick was the one that escaped notice. 

Then one really gets used to degenerate-case dialetheism about liar-like paradox and starts to embrace it and then one is forced to reckon. 

One funny thing is that many dialetheists nowadays may agree with me that it’s fine and perhaps even good to start logic instruction with bivalent logic. I am in danger of seeming to have no distinctive position. The difference is subtle and is about what is emphasised, what is treated as an unimportant practical matter, etc. 

***

One thing is very important: logical laws that fail in LP but hold classically do not automatically become only maintainable in a ‘usually’ form. We have a concept of nonparadoxical sentences and propositions and we can maintain that the laws hold of absolutely all of them.

(We must remember that logical laws are in the first place thought of as applying to sentences or schemas meant in a particular way or reckoned as part of a language—or alternatively to propositions. It’s not as if they are about absolutely everything including say oranges (at least, not in the relevant sense). This is a hard point to bring out but it feels important. 

Approached from another angle: if logic is just about a particular kind of thing—declarative sentences, propositions—why does it have such an aura of generality? Because this particular kind of thing plays an enormous and widely ramified role in our lives! Especially if we’re “intellectual types” and especially if we’re a certain kind thereof! Seen this way, excluding dialethia from standard logic’s scope is no real cause for embarrassment or disappointment or disenchantment. There is this odd kind of case, there are interesting proposals about how to include it, and that’s it. It just is what it is.

I need to say more about the two broad approaches of dialetheists - LP or something like that with the model theory thought of as principled and tracking what’s really going on vs. this kind of industry I’m dimly aware of of trying to get back as much classical stuff as possible while not exploding. I should perhaps talk to Ripley about this. 

This all connects up with my perspicuous representation stuff too. Because wanting cool stuff to do is now one reason why classical logic gets short schrift or denigrated merely for its bivalence and explosion. Seeing that there’s plenty of other cool stuff to do without messing with bivalence and explosion makes it clearer that there are multiple directions for logic to grow in and we can rightly regard classical logic with standard modern notation as the centrepiece. (For us, at this time in history, and given our nature.)

I don’t want to be stupid about the role of paradox in modern logic. It is there. It is undoubtedly very important. It notably plays a vital role in particular (here I mean ‘vital’ quite specifically, wanting the association with life and all that, it’s not merely functioning as a synonym of ‘important’ here).

“Look, we wanted to know which argument forms were valid. And in light of the liar and dialetheism being the truth about it, we have to accept that lots of the ones we thought were just aren’t! Don’t try to weasel out of that”

There’s a lot in that. One interesting thing emerging for me here is that it’s not merely the ‘well you don’t believe everything do you, so you have to reject explosion’ thought which leads to rejecting explosion. You can also just track through the definition of validity and show invalidity ‘Look, it is possible after all for A ∧ ¬A to be true after all (and hence possible for it to be true while some conclusion B is false). What we overlooked is that A is in some cases both true and false, and so therefore is the conjunction of A with its negation. 

Another good thing I’ve just noticed—it feels like good news for my point of view: I think we can maintain the generality of classical logic in another way (in contrast to saying it’s about the nonparadoxical sentences/propositions). Namely, by revising what we mean by ‘valid’ usually—namely, being clear that we’re talking about ruling out the case of the premises all being just true (i.e. not also false) and the conclusion not being so. (Alternative worth comparing: changing the last bit to ‘the conclusion being just false’.) (The latter could be implemented technically with a notion of “anti-designated” value.)

In what sense can classical logic be wrong?

Failing to capture stuff is not being wrong, so for e.g. indicative conditionals not being material conditionals does not mean that classical logic is wrong, only that it doesn’t by itself handle the validity or otherwise of arguments involving indicative conditionals.

But the threat from truth-theoretic considerations, gaps and gluts, is different here.

Also the threat from the more general idea that there’s a relevant sense of logical consequence whereby explosion (ex falso quodiblet) isn’t valid. 

In both cases things come to a head with: this argument is valid according to classical logic but really isn’t.

With the first threat, the problem is not in the notion of validity—that can stay. With the second, the frame of mind is that of wanting a conception of consequence/validity in which explosion simply lacks that status, isn’t sort of pseudo-valid, i.e. valid in a stronger pseudo-logic where we ignore some real possibilities. 

With the first, you can say: explosion instances are often good arguments in some sense, even if not strictly valid. They’re truth-preserving w.r.t. all cases not involving dialetheia. Not, of course, good arguments in the sense that you’d ever follow them from premise to conclusion! But we can say yep, anything “follows from” a contradiction if we ignore models in which dialtheia occur. Provided you know you have no dialethia in the mix, you have your guarantee that you’re not gonna be led from truth to falsity. 

On this first conception, i.e. the dialethic one, how does classical logic err? Where does it go wrong? 

‘You say it is not possible for P&~P to be true while Q is false. But it is possible, because, when you interpret P, sometimes your classical model which corresponds to reality, while it rightly captures the fact that P is true (false), goes wrong in not also capturing the fact that P is false (true). Well, actually, in these cases, two of your classical models will correspond to reality.’ (One fix, make the valuation function a relation—on that implementation, we can say the classical model rightly maps P to T (F) but fails to also map it to F (T). Another, add a third truth value representing the dialethic status - but that’s a different mode of presentation and so you don’t get the perspicuous sense in which the classical model just leaves something out. — In the relation mode of presentation, you can take a classical model with one letter and get two full models - the one where you do nothing, and the one where you also map it to the other value. But with the three-value mode of presentation, while a classical model is straightforwardly still a special case of one of these full-story models, it is no longer the case that you can take a classical model of a situation and make it correct by only adding something (or doing nothing)-if you have a dialethia, you have to unmap it from T and instead map it to X. So that makes it look like the classical model has said something wrong — and of course we can look at a classical model what way, if we treat T as “true and true only” or regard the model as making an implicit claim to telling the whole story about which letters have which of the two properties truth and falsity. But here the principle of charity, and general good sense, should tell us to not regard that as part of classical logic itself. So let’s put that aside.

From this point of view, classical logic knows what validity is alright, and doesn’t get any individual thing wrong semantically, but the semantics is incomplete—the models lack information sometimes (and the way the notion of model is set up precludes putting it in). And this leads to cases where counterexamples fail to show up, because the classical models miss parts of the picture without which the picture doesn’t show a counterexample.

Notes on Modal Issues Regarding the Ontology of Propositions

Cross-posted here.

A true sentence like ‘John is here in this room’, and its Twin Earth counterpart, express different propositions, since they are about distinct people. And that means that propositions sometimes constitutively involve particular external things that they are about.

What, in light of this, should we say about how, if at all, what propositions there are—what claims exist—varies across possible worlds?

One side of this issue is: could propositions like the ones expressed by a normal true use of ‘John is here in this room’ have failed to exist? Do they fail to exist in (or with respect to, perhaps?) all worlds in which John does not exist? (I set aside Williamsonian necessitarianism about what there is.)

My notion of the internal meaning of a sentence, or the way it is used, gives me a way of agreeing that there’s something right about the idea that the meanings of sentences are just there and exist necessarily. Given a normal occurrence of ‘John is here in this room’, the way the sentence is being used—which it has in common with its Twin Earth counterpart—may be regarded as a pure abstract object, like a way of dancing, which we can say is just there and could in no sense have failed to exist.

Here is another question we might ask: propositions about particular people and physical things—suppose they do exist in some possible worlds apart from the actual world. But do they themselves have different properties in worlds where the things they are about have different properties? A way of using a sentence, we might say, is just what it is and doesn’t have different intrinsic properties at any rate in different worlds—it will of course have different extrinsic properties such as ‘having been instantiated by someone wearing a blue hat’. But if a claim constitutively involves the object it is about, is the object with respect to the claim like a diamond set in a piece of jewellry, so that the piece’s properties change whenever the diamond’s do, since the diamond is part of it? I think perhaps this need not be so. We could instead use the model of something which needs to be tied to something else, and which disappears, or at least ceases to be that thing, if we cut the tie or remove the something else.

A tremendous complicating factor is that there are undoubtedly, in some sense, claims about things that do not in fact exist. We cannot here follow Kripke in Reference and Existence into the view that these sentences do not in fact express propositions, anymore than we should follow him in analyzing particular existential statements as talking about whether there is such-and-such a proposition. (That theory is I think clearly tortured but this is not the place to mount objections but see Postscript.) And recall there that even Kripke was keen to avoid the seeming absurdity of having to hold that the correct analysis of a statement can depend on whether it is true or false. However! It seems to me there is one thing in this general vicinity which we might indeed have to come to terms with. Namely, that the modal profiles and identity conditions of propositions expressed by statements involving names that happen to be empty differ from those of propositions expressed by statements which are being used in exactly the same way but where the names aren’t empty. 

Someone might want to say: just because we can’t pick out particular propositions about physical objects and people etc. that do not actually exist, doesn’t mean they don’t exist. (Anymore than the fact that non-actual people can’t pick out our propositions means that they don’t exist.) But this is only really correct given something like Lewisian modal realism.

‘What if Vulcan had existed?’—Are we to follow Kripke in his view of unicorns and apply that even to the case of names, i.e. say that there is no particular possibility in question at all here? A lot of what I am otherwise tending toward does seem to be leading me that way—but I suspect that here the shoe might really pinch, and that dwelling on this part of the issue and trying to do it justice will lead to a breakthrough—-a better view. A kind of more nuanced view which, pace recent Williamson, would not be a case of overfitting.

‘What if the claims made by some astronomers about Vulcan had been true? I don’t mean what if they had been right when they spoke. I mean, consider the claims they expressed about Vulcan. What if those claims had been true? Is there a possible world in which they are true?’

Postscript. It seems a very important objection to Kripke’s analysis of negative existentials in R&E that he is kicking the can down the road. For how does it get to be true that ‘There is no such proposition as that Vulcan exists’ expresses a true proposition? If we interpret it metalinguistically, it’s wrong as an analysis. So then how do we interpret it? The ‘no such’ has a soothing effect and as it were shrouds the occurrence of ‘Vulcan’ in a haze. But we still need to account for what it’s doing there and how we get different statements when we pop in different empty names.

This post is dedicated to the memory of the late Queen Elizabeth II.

Meaning and Metaphysical Necessity - now out with Routledge

 

My book Meaning and Metaphysical Necessity is now out with Routledge. I began seriously developing the ideas in it in 2011 when I began my PhD, which is also the year this blog started. Many of the posts here over the years were devoted to working out the views in the book.

The Threefold Root of the How-Question About Mathematical Knowledge

Platonism is the default, almost obviously correct view about mathematical objects. One of the major things that puts pressure on Platonism is the question 'How do we know about mathematical objects, then?'. What gives this question its power? I think three things conspire and that the third might be under-appreciated:

1. Real justificatory demands internal to mathematical discourse. For particular mathematical claims, there are very real 'How do we know?' questions, and they have substantive mathematical answers. The impulse to ask the question then gets generalized to mathematical knowledge in general, except that then there's no substantial answer.

2. A feeling of impossibility engendered by a causal theory of knowledge. If you only think about certain kinds of knowledge, it can seem plausible that, in general, the way we get to know about things is via their causal impacts on us. This then makes mathematical knowledge seem impossible.

3. Our deeply-ingrained habit of giving reasons. The social impulse to justify one's claims to another is hacked by a monster: the philosophical question at the heart of the epistemology of mathematics.

If it were just 1 and 2 getting tangled up with each other, the how-question would not be so persistent. With existing philosophical understanding we'd be able to see our way past it. But 3 hasn't been excavated yet and that keeps the whole thing going.

A Puzzle about Abbreviation and Self-Reference

Let us use 'ONE' as an abbreviation of 'This sentence token contains more than one word token'. Now consider whether the following is true:

    ONE

Major Inaccuracies in Misak's review of Journey to the Edge of Reason, a new Gödel Biography

In the Times Literary Supplement there is a review of a new biography of Gödel by philosopher Cheryl Misak. The review is called 'What are the limits of logic? How a groundbreaking logician lost control'. This paragraph contains two major inaccuracies:

Gödel proved that if a statement in first-order logic is well formed (that is to say, it follows the syntactic rules for the formal language correctly), then there is a formal proof of it. But his second doctorate, or Habilitation, published in 1931, showed that in any formal system that includes arithmetic, there will always be statements that are both true and unprovable. The answer to the Entscheidungsproblem was, therefore, negative.

The first one is that being well formed is like being grammatically correct - among the well formed formulas of first-order logic, there are formulas that are false no matter what (false on all models or interpretations), formulas that can go either way, and formulas that are true no matter what (these ones are often called logical truths, or logically valid formulas). What Gödel showed is that for every logical truth, there is a proof that it's a logical truth. 

The second major inaccuracy is that the answer to the decision problem (Entscheidungsproblem) is not shown to be negative by the incompleteness theorem that Misak alludes to. The negative answer became known only in 1936, when Alonzo Church and Alan Turing independently showed it.

Reversing Logical Nihilism - Forthcoming in Synthese

Final draft available on PhilPapers.

Abstract: Gillian Russell has recently proposed counterexamples to such elementary argument forms as Conjunction Introduction (e.g. ‘Snow is white. Grass is green. Therefore, snow is white and grass is green’) and Identity (e.g. ‘Snow is white. Therefore, snow is white’). These purported counterexamples involve expressions that are sensitive to linguistic context—for example, a sentence which is true when it appears alone but false when embedded in a larger sentence. If they are genuine counterexamples, it looks as though logical nihilism—the view that there are no valid argument forms—might be true. In this paper, I argue that the purported counterexamples are not genuine, on the grounds that they equivocate. Having defused the threat of logical nihilism, I argue that the kind of linguistic context sensitivity at work in Russell’s purported counterexamples, if taken seriously, far from leading to logical nihilism, reveals new, previously undreamt-of valid forms. By way of proof of concept I present a simple logic, Solo-Only Propositional Logic (SOPL), designed to capture some of them. Along the way, some interesting subtleties about the fallacy of equivocation are revealed.

Validity as (Material!) Truth-Preservation in Virtue of Form

Forthcoming in Analytic Philosophy and available on PhilPapers.

Abstract:

According to a standard story, part of what we have in mind when we say that an argument is valid is that it is necessarily truth preserving: if the premises are true, the conclusion must also be true. But—the story continues—that’s not enough, since ‘Roses are red, therefore roses are coloured’ for example, while it may be necessarily truth-preserving, is not so in virtue of form. Thus we arrive at a standard contemporary characterisation of validity: an argument is valid when it is NTP in virtue of form. Here I argue that we can and should drop the N; the resulting account is simpler, less problematic, and performs just as well with examples.

Sprachlogik on Substack

Here.

Dialetheism and Transition States

I've been thinking recently about an argument given by Graham Priest for the view that, when you're on your way out of a room, there's a point in time at which you're both in the room and not in the room. 

For those who believe in true contradictions (dialethias) already because of Liar-like phenomena, whether or not this kind of example also exist may not seem like such an urgent issue. But if, like me, you are drawn to a gappy rather than a glutty response to Liar-like paradoxes, this sort of argument becomes more important, since it may take you from not believing in true contradictions to believing in them.

Priest's argument appears on p. 415 of his 'What is So Bad About Contradictions?' and is discussed in Section 3.4. of the SEP article on dialetheism. From the latter:

Transition states: when I exit the room, I am inside the room at one time, and outside of it at another. Given the continuity of motion, there must be a precise instant in time, call it $t$, at which I leave the room. Am I inside the room or outside at time $t$? Four answers are available: (a) I am inside; (b) I am outside; (c) I am both; and (d) I am neither. There is a strong intuition that (a) and (b) are ruled out by symmetry considerations: choosing either would be completely arbitrary. (This intuition is not at all unique to dialetheists: see the article on boundaries in general.) As for (d): if I am neither inside not outside the room, then I am not inside and not-not inside; therefore, I am either inside and not inside (option (c)), or not inside and not-not inside (which follows from option (d)); in both cases, a dialetheic situation. Or so it has been argued. For a recent description of inconsistent boundaries using formal mereology, see Weber and Cotnoir 2015.

I will now outline what I think we should say in response. 

The appeal to 'symmetry considerations' is where the trouble is in this argument. Let us assume for a moment that there are no true contradictions and see what we can say that is consistent with that commonsense view. On pain of contradiction, the notion of being 'inside' a room is not both true of me and false of me in this case. Now, we can grant that any notion of being 'inside' which is true of me in this case is in a sense biased in favour of insideness, and any notion of being 'inside' which is false of me in this case is biased against insideness. But probably, our normal notion of 'inside' as applied to rooms is just not determinate here; our linguistic behaviour doesn't make it the case that we are using the inside-biased notion rather than the outside-biased notion, nor does it make the opposite the case. But if we need to, we can just pick one of these notions, and everything will be OK as long as this is understood by speakers and hearers.

To me, this seems highly plausible. And it lets us maintain that there are no true contradictions. Let's grant Priest that it's bad philosophy to just reject outright the idea that there might be true contradictions. But if we haven't already adopted dialetheism, which is a pretty radical view, then other things equal, we should look for less drastic ways to make sense of examples like this. And that's what I've sketched above.

Forthcoming in Philosophical Studies: A Simple Theory of Rigidity

 

After wrestling inconclusively with this topic a couple of years ago on this blog, I came to a much clearer view about rigidity, which I set forth in this paper:

A Simple Theory of Rigidity

The notion of rigidity looms large in philosophy of language, but is beset by difficulties. This paper proposes a simple theory of rigidity, according to which an expression has a world-relative semantic property rigidly when it has that property at, or with respect to, all worlds. Just as names, and certain descriptions like The square root of 4, rigidly designate their referents, so too are necessary truths rigidly true, and so too does cat rigidly have only animals in its extension. After spelling out the theory, I argue that it enables us to avoid the headaches that attend the misbegotten desire to have a simple rigid/non-rigid distinction that applies to expressions, giving us a simple solution to the problem of generalizing the notion of rigidity beyond singular terms.

Pre-print available at PhilPapers

On the Failures of Nonsense-Policing and Ordinary Language Philosophy

In this post I reflect on the failures of nonsense-policing and ordinary language philosophy, and the fact that notwithstanding these failures, paying critical attention to semantic issues is of central importance in philosophy, and in metaphysics as well as philosophy of language. 

The early Twentieth Century saw a surge of interest in the idea that the apparently intractable problems of philosophy come from misunderstanding language, and that philosophical questions are often unanswerable not because they are too difficult for us, but because they fail to make sense, or we fail to understand them properly.

This idea took various forms. The logical positivists attempted to give general criteria of meaningfulness using the notion of verification, the early Wittgenstein aims at a comprehensive, general theory of how language represent which leaves no place for genuine philosophical propositions, and more specific doctrines in logic and philosophy of language were used to dissolve particular problems.

Logical positivists attempted to formulate a criterion of meaningfulness in terms of the notion of verifiability. The basic idea is that a meaningful sentence must either be analytic (i.e. true in virtue of meaning) or verifiable in principle by experience. Philosophical sentences which are neither analytic nor verifiable experientially are therefore meaningless if this idea is correct, and works of metaphysics appear to be full of such sentences. As powerful as this idea seemed to the logical positivists, attempts to work it out in detail ran into trouble. There are also serious problems affecting even the basic idea; what about statements about minute happenings in the distant past, or events outside our light cone? (Such cases are more or less worrying depending on how one thinks about ‘verifiability in principle’.) And what about competing theoretical claims that do not appear to be analytic but where the contest does not appear to be settled by any possible experience? These arise in science as well as philosophy and we seem to decide about them on the basis of things like theoretical virtues rather than empirical tests. Thus the whole idea of experiential verifiability as a criterion of meaningfulness has been largely abandoned (at least in academic philosophy; it enjoys a vigorous half-life, along with Popper’s idea that truly scientific theories must be falsifiable, in the wider intellectual culture).

Wittgenstein in the Tractatus (a source of inspiration for the verificationists) attempts to say in general how meaningful propositions are constructed. In numbered, often cryptic remarks, we are given a beautiful, austere picture of how language represents. Elementary propositions are constructed out of names, and more complex propositions are constructed from them by simple logical operations. Anything which can’t be constructed in this way is not a genuine proposition. And many sentences in philosophical works fail to be genuine propositions. Wittgenstein’s proposal is that, with theses and questions in metaphysical philosophy, something akin to what is wrong with the sentence ‘Mortality is Socrates’ has gone wrong, only more subtly so.

(Wittgenstein’s later work is also replete with denials of sense, although it is up for debate what these come to and what they are based on. Assessing expressions for sense becomes a looser, more occasion-sensitive affair in the later work, as opposed to being based on some general theory of meaningfulness. Sense-denying aspects of Wittgenstein’s work, and interpreters of his work who emphasise them (e.g. P.M.S. Hacker), have come in for extensive criticism, and are seldom echoed in more recent contemporary philosophy. I see them as an unfortunate holdover from the early work, and as marking a place where Wittgenstein’s ideas require both revision and further development.)

Apart from general criteria of meaningfulness and overarching theories of what can be said, logical doctrines about particular parts of language have also been used to dispense with philosophical problems by denying sense. A famous example is the doctrine, defended by Bertrand Russell and wielded by many later writers (a prominent example being Rudolph Carnap), that ‘exists’ cannot be used with proper names. This is a kind of modern logical version of Kant’s doctrine that existence is not a predicate. From a contemporary point of view, this seems hopelessly revisionary. What we ordinarily call ‘proper names’ can meaningfully be put together with ‘exists’, and logically minded philosophers must accommodate this fact as best they can. 

The above views have in common that they are supposed to be based on the technical foundation of modern logic. Another influential Twentieth Century development of the idea that a better understanding of linguistic meaning is methodologically crucial is the Ordinary Language Philosophy (OLP) movement, as spearheaded by J.L. Austin. In a way it involves a kind of nonsense policing, but there is no general, technical policy that is being enforced; the OLP nonsense police, if that’s what they are, know that they’re operating in a complicated society and will require good judgement. This no doubt enhanced OLP’s plausibility in the wake of logical positivism’s failure.

I once heard from a mentor that in the 1960’s there was a feeling in the air that the traditional problems of philosophy would soon be cleared up by means of OLP. That this hasn’t happened should be uncontroversial. Why it hasn’t happened is more controversial, but we can speculate. One factor seems to be that the urge to use language in extraordinary ways is deep-rooted. No amount of attention to ordinary usage can stop it. Metaphysicians have become more self-conscious about the fact that their use of key terminology may depart from ordinary usage, and have found ways to persist in it nonetheless. (For example, in response to arguments by Eli Hirsch to the effect that non-commonsensical claims in ontology simply couldn’t be true, since they fly in the face of metasemantic wisdom - charity demands that we interpret natural language sentences so they aren’t radically false - Theodore Sider has argued that non-commonsensical metaphysical views should be regarded as being stated in Ontologese, a special non-ordinary language. For the Hirsch-Sider debate, see (in dialectical order) Hirsch (2010) (a collection of essays), Sider (2009), Hirsch (2008) and Sider (2014).)

Another factor may be a lack of technical sophistication: philosophy can get quite technical, but OLP tends not to come along for the ride. (Perhaps proponents of OLP could have done better here, either by coming along for the ride in some fashion or by forestalling misguided research programmes.) OLP at its most interesting can also become quite idiosyncratic and fragile, in contrast to a more recent trend of international and interpersonal cooperation. One of the most intriguing developments of OLP, the work of Stanley Cavell, typifies this tendency: you see all this sophistication, all these interesting scruples, but you have to be a special kind of person in a special kind of culture to appreciate it. Interesting as it may be, such work can be difficult to make use of in the sort of thing that Bertrand Russell called ‘technical philosophy’. Above all, the ordinary language philosophy of the mid Twentieth Century has simply been sidelined by more vital developments in connection with which it appears at least to have little to offer. Quine, Putnam, Kripke, Lewis and many others come on the scene, we get a whole raft of topics and problems to work on, and ordinary language philosophy falls by the wayside. 

The failures of nonsense-policing and ordinary language philosophy have had the unfortunate consequence of leading to complacency about sense in contemporary philosophy; a kind of presumption of innocence, where once basic standards of clarity have been met, we tend to take it for granted that philosophers’ utterances are meaningful and that we understand well enough what they mean. According to this way of thinking, the important work in philosophy tends to consist, not in inquiring not into the sense of expressions, but rather into which claims are true.

But the failure of nonsense-policing should not be taken to suggest that the analysis of meaning is not of central importance in philosophy. There may not be much of a future for denying meaning to animating words and phrases, but there remains a need to be critical and inquisitive about what they do mean. We are often being critical in this way even if we aren’t explicitly talking about meaning, or aren’t doing so systematically. But to get further we need to be able to be self-conscious and systematic, without losing crucial data that doesn’t fit well with the kind of thin, reference-based conception of meaning that now seems to hold sway again in philosophy.

References

Hirsch, Eli (2010). Quantifier Variance and Realism: Essays in Metaontology. Oxford University Press.

Hirsch, Eli (2008). Language, ontology, and structure. Noûs 42 (3):509-528.

Sider, Theodore (2009). Ontological realism. In David John Chalmers, David Manley & Ryan Wasserman (eds.), Metametaphysics: New Essays on the Foundations of Ontology. Oxford University Press. pp. 384-423.

Sider, Theodore (2014). Hirsch's Attack on Ontologese. Noûs 48 (3):565-572.