Natural and Projectible Predicates

Rachael remarks on the 'structure and similarity' discussion:

Should we distinguish between predicates that are projectable and predicates that are natural? "Green", "ultraviolety-looking to bees", "owned by Rachael", and "tasty to alpacas" are fairly projectable, but I doubt they're natural. I don't expect a bee to care which objects are green, a mouse to care which objects are owned by Rachael, or a human (who doesn't have a special interest in bees or alpacas) to care which objects are ultraviolety-looking to bees or tasty to alpacas. There's a sense in which all the above concepts are parochial, and are only worth adopting because they're convenient. Furthermore, there's a sense in which there's no conflict between these different ways of carving up the world: I don't think the alpacas are wrong, and I might find it very important to adopt their concepts when interacting with them.

Also, maybe "Having mass m before time t or mass m* after" is an example of a natural predicate that isn't projectable.

That last example sounds gerrymandered (i.e. not a natural way to carve things up) to me. I'd need to hear more about why we'd consider it 'natural'. (Note that complex predicates may invoke natural terms like 'mass' in a gerrymandered or non-natural manner.) On the other hand, I'm also unsure why green and ultraviolet are thought not to be very natural. There is a natural respect -- namely, surface reflectance properties -- in which all green things (or all ultraviolet things) exhibit a genuine similarity.

The other examples are plausibly less natural, but also (and, I imagine, to the same degree) unprojectible. Here I should clarify something that may not have been clear in my first post. 'Projectibility' does not just mean stability across time, i.e. that if something satisfies the predicate now, it will also do so in future. Any tenseless predicate, however gerrymandered -- e.g. 'exists in 1907 or 2008' -- will be temporally stable in this sense. Genuine projectibility is more general, since we can inductively project along dimensions other than time. If a bunch of Fs are green, that may be evidence that other Fs (and not just these same ones in future) are also green. On the other hand, if a bunch of Fs are owned by Rachael, that's probably not enough to justifably project ownership-by-Rachael onto any other arbitrary F.*

Overall, then, I remain of the opinion that 'natural' predicates, i.e. those that carve nature at the joints, or highlight objective similarities, are also those that will tend to support inductive projection.

[* = I'm not sure if that's the best way to explain projectibility. Any suggestions?]

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Sider on Semantic and Metaphysical Intuitions

It is important to separate the two kinds of intuitions. Suppose you are initially inclined to intuit thus: "the property of being a dog is intrinsic". This might well be because you are simply presupposing the worm view [of 4-d objects], and thus presupposing that 'being a dog' refers to the property of being a dog-worm, and metaphysically intuiting that this property is intrinsic. It might well be that, once the question is raised of whether the worm-view or the stage-view is correct, your initial conviction disappears, and is replaced with agnosticism about whether "being a dog is intrinsic", despite your certainty that being a dog-worm is intrinsic and being a dog-stage is extrinsic.

[From his paper on counterpart theory: 'Beyond the Humphrey Objection'.]

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Natural Baselines

After my uncharacteristic espousal of some form of metaphysical realism, I feel a more deflationary argument is in order. In particular, I want to explore the idea that there is no objective basis for talk of the 'natural progression of things', or a default outcome which an agent's actions may interfere with. In other words: is there a natural distinction to be made between 'doing' and 'allowing'?

I've been reading Dan Dennett's 'A route to intelligence: oversimplify and self-monitor', in which he discusses the queer idea of "changing the course of history":

How could you change the course of history? From what to what? If history is simply the sequence of events that actually occur, then of course you can't change history. People say you can't change the past, and that's true enough, but then you can't change the future either...

[O]ne has to be thinking of an anticipated history, the way history is going to go ceteris paribus, the way history is going to go unless someone does something, or until someone does something, or in spite of what someone does. These verbs of agency can have no foothold outside the framework of a projected, aniticpated history, even when they are used to characterize the effects brought about by entirely inanimate objects.

He goes on to describe a scenario whereby a meteor is heading towards the earth, and we're all frantic until an unnoticed second meteor deflects the first one, "narrowly averting the catastrophe, preventing calamity." However, given full information, we could have seen that "there was never going to be a catastrophe. It was merely an anticipated catastrophe -- a mis-anticipated catastrophe." Dennett thus suggests that the sense in which the meteor was 'set' to hit earth is merely epistemic, rather than reflecting any natural disposition or 'default outcome' in the world, from which we were narrowly saved.

I'm not sure that's the full answer, though. There seems a sense in which the meteor really was, quite literally, 'on course' to hit the earth. It was 'deflected', which is precisely to say that its course was changed. This may be reflected in the modal fact (if it is one) that in most close possible worlds, the catastrophe indeed occurs. It's an open question whether this modal fact actually holds of the scenario, however. It might if small changes to the course of the second meteor would cause it to miss the first, while equivalent changes to the first meteor would not have caused it to miss earth. Otherwise - if the course of catastrophe was not modally robust in the first place - my modal account implies that the meteor was not really 'set' to hit the earth in any objective sense at all.

Let's see how this modal account applies to the puzzle discussed in my old post on framing thought experiments:

Weatherson notes that "where we set the 'zero-point' or status quo makes a big difference for how we act." But is there really any fact of the matter about what the 'default' outcome is? Kahneman and Tversky's classic example seems to suggest that this is merely a difference in our descriptions, not in reality. Whether you say that 400/600 will die, or that 200/600 will be saved, you describe one and the same fact. But the descriptions differ in their implied baseline, or what they convey as being "the natural progression of things". Could there be a metaphysical fact of the matter regarding where the true baseline lies? What sort of fact could this be, that would tell us whether a survivor was saved from the jaws of death, or whether it was simply a matter of death failing to cut his life tragically short? When faced with branching possibilities, how can we say that one is the "default" path of fate, and the other some kind of unnatural "diversion"? (But if we can't do this, then what is our basis for caring more about "losses" than "forfeited gains"? Doesn't this distinction require a baseline?)

My new suggestion is that the modal facts can provide such a baseline. The baseline is whichever event (dying or being saved) occurs in most close possible worlds. If you are overwhelmingly likely to obtain some benefit, then failure to obtain it in the actual world is properly classified as a loss, and not merely a forfeited gain.

Eh, so much for deflationism. It turns out I'm a "realist" about baselines too! A somewhat revisionary one, though. This certainly doesn't match our common understanding of the doing/allowing distinction, and nor would I expect it to have such (or, perhaps, any) normative significance. What do you think?

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Structure and Similarity

I once thought that all possible ways of categorizing the world were metaphysically on a par. We may find it more useful to talk of tables and chairs, but objectively speaking this way of dividing up the world is not metaphysically privileged over alternatives that seem "gerrymandered" to us, e.g. combining chairs and cockroaches into a single category.

I now realize that my past self was very silly. Though it may at first seem puzzling that there could be privileged categories, or 'structure' to the world, it seems perfectly obvious that some pairings are objectively more similar than others. Two chairs are more alike -- have more natural properties in common -- than a chair and a cockroach, and this is nothing to do with our words and everything to do with how the world is. (A tribe might have a but a single word X that means 'chair or cockroach', but in that case their language would be objectively inferior to ours in this respect, for it fails to carve nature at the joints.)

One way to bring this out is to think about projectability, or what properties you can reason inductively from. All the emeralds I've seen so far have been green, so I expect the first emerald I see after 2020 will also be green. That seems a perfectly reasonable induction. On the other hand: "All emeralds I've seen so far have been grue, so I expect the first emerald I see after 2020 will also be grue" is clearly not good reasoning. This is because green is a more natural property than grue. It is an objectively better way to categorize reality.

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Ontological Reduction

Is consciousness ontologically irreducible? Richard Brown thinks that the question is incoherent:

What [the identity theorist] says is that there is only ONE thing there, the brain and its various states, and you cannot reduce something to itself!

He goes on to contrast this with linguistic, theoretical reductions, and explains how those are irrelevant to the debate between physicalists and dualists. I agree with that part. But I think he's wrong to think that linguistic reductions are the only coherent form of reduction.

We can see this because, as I've been saying all along, the question is whether qualia are reducible in the same sense that tables and chairs are, whatever that may be. Now, it's an open question whether our talk of tables and chairs could be replaced by (perhaps complicated and long-winded) talk purely in the language of microphysical theory. But we don't care about talk. What matters is that the facts about tables are obviously settled by the microphysical facts. If you have a coarse-grained conception of 'facts', maybe they are even one and the same fact. Even so, we can get to a metaphysical notion of reduction by appeal to the truthmakers for our sentences. Regardless of whether table talk is linguistically replaceable by particle talk, there's no question that the microphysical facts are what make our table statements true (if they are true).

Once you've included the microphysical facts in your base facts, you do not need to add any further 'table facts' in addition. Those are already covered. It is in this sense that table facts are reducible to physical facts. And it is in this sense that the question of physicalism comes down to the question whether qualia are reducible. It is simply the question whether we need to add phenomenal facts to our fundamental base facts, or whether they "come along for free" (like tables do) given the physical facts P.

(I find it convenient to use the term 'reducible' to invoke this idea, but you're of course free to pick another word if you prefer. What's not helpful is to simply insist, "the debate between the dualist and the materialist is in no way a debate about reduction", and so ignore my underlying idea concerning what the debate is about. RB wanted to focus on what counts as 'physical' or 'non-physical', but that soon degrades into semantics. The substantive issue, as I see things, is whether we must include qualia as an additional primitive among the base facts. This understanding makes it clear why RB's "non-physical zombie" parody argument falls flat (to put it mildly). See my 'Zombie Review' for more detail.)

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Subtracting Presuppositions

Follow-up to: Logical Subtraction and Partial Truth

Yablo proposes that (1) the real content of a statement S is what it says as opposed to presupposes; (2) what it says is what S adds to the presupposition π. That is, the real content R = S - π.

How can we tell what's presupposed? Linguists have developed various tests for this, including the negation test: Denying The # of planets is 8 is not thereby to assert There is no such entity or it is not 8. No, whether we assert or deny the claim, this way of talking presupposes numbers either way. So the real content is merely about how things stand concretely so far as the planets are concerned.

Plugging into the formula:
R = S - π
    = 'The # of planets is 8' - 'There are numbers'.

This remainder, the real content of what's said, is true even if the literal statement S isn't (due to the false presupposition). S is merely partly true, but it's true in the part that we care about.

Here's a vital question for metaphysicians concerned with ontological commitment: Are we committed to the truth of our presuppositions, or merely to what we say (i.e. what our assertions add to what's presupposed)? Ordinary talk presupposes all sorts of ontological extravagance: composite objects, numbers, propositions, properties, tensed reality (past/future), mere possibilia, etc. Such talk helps us to convey important truths, some of which may not even be possible to express in less ontologically loaded terms. So it would be nice if we could maintain this talk in good conscience, without thereby committing ourselves to the ontological presuppositions. Can we?

Sometimes, at least, we can knowingly adopt a false presupposition. Yablo mentions talk of 'the King' to denote Harold the usurper. Harold is not really the King, we all know -- the King is locked away in the dungeon. But nonetheless we may use 'The King is coming!' to warn of Harold's approach. This does not commit one to thinking that Harold truly is the King rather than a mere usurper. The false presupposition is adopted merely for sake of communication, and can be safely subtracted to get at the real content of our assertions. Similarly, we may think, for ontological presuppositions. We presuppose that there are numbers in order to more easily describe how things stand in concrete reality. But we may do this while remaining neutral on the question whether the presupposition is really true.

Yablo also briefly mentioned the popular meta-ontological view that various ontological disputes (e.g. whether numbers really exist) are 'empty' or meaningless. He suggests that we have this intuition in cases where the presupposition that X really exists is perfectly extricable from the ordinary claims which rest upon it. We have no trouble simply subtracting away the disputed metaphysical claims, and assessing the concrete remainder. So it seems like the metaphysics isn't really doing anything. That seems to describe my intuitions pretty well, I must admit. But what are the implications for meta-ontology? Can the subtraction method vindicate our deflationary intuitions? Or does it debunk them, suggesting that there is a further question there -- just not one we're typically concerned with in everyday life? Or must we look elsewhere to adjudicate this issue?

Fascinating questions, I reckon. Now if only I could find some answers...

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Logical Subtraction and Partial Truth

Stephen Yablo gave a very impressive series of lectures here last week. His core insight was that often we can communicate important truths by way of assertions that are literally false. The rough explanation for this is that the assertion, though false, may be "partly true", or "true insofar as it concerns a certain subject matter." For example, 'the number of dragons is zero' may be literally false if numbers do not exist. But it is partly true, i.e. true in what it says about dragons (namely, that there aren't any). If you take the literal meaning, and subtract the claim that there are numbers, the remaining content is wholly true.

Sometimes logical subtraction seems unproblematic, as the subtracted element is "perfectly extricable" from what's being said. Other cases, however, are more problematic. When you subtract the redness from scarlet, what's left? 'Tom [the tomato] is scarlet - Tom is red' does not leave any remainder that we can make sense of. It seems perfectly inextricable. Then there may be inbetween cases, such as Wittgenstein's famous question: "what is left over if I subtract the fact that my arm goes up from the fact that I raise my arm?" We have some grasp of this, but as Jaeger has pointed out, "it is not the case that there is exactly one statement R such that 'R & my arm goes up' is logically equivalent to 'I raise my arm'."

Yablo's solution is to say that "P-Q always exists, but it doesn't always project very far out of the Q-region [of logical space]. Inextricability simply means that it is hard [or impossible] to evaluate P-Q in worlds where Q fails."

Intuitively, we can say that:
(i) P-Q is false iff P adds falsity to Q.
(ii) P-Q is true iff not-P adds falsity to Q.
(iii) If neither P nor its negation adds falsity to Q, then P-Q is undefined (lacks a truth value).

Yablo systematizes our intuitive judgments here by appeal to truthmakers, or the reasons why a proposition is true/false. P "adds falsity" to Q if it is false for a Q-compatible reason, i.e. there is a Q-compatible falsity-maker for P.

Example: Let P = 'The King of France is bald' and Q = 'France has a King'. Then P-Q is false, because of the following Q-compatible falsity-maker for P: the list of all the bald people, none of whom is a King of France. This falsity-maker could exist, and so make P false, even if Q were true and France did have a King. This shows that P is false for reasons over and above the falsity of its presupposition Q.

Here is a bit more technical detail. Let R be a potential candidate for P-Q. Yablo suggests that R is a successful candidate, i.e. R extrapolates P beyond Q, iff the following three conditions are satisfied:
- "Equivalence: within Q, R is true (false) in a world iff P is true (false)." That is, if R = P-Q, then it had better be the case that R&Q = P.
- "Reasons: within Q, a world is R (~R) for the same reasons it is P&Q rather than ~P&Q (...)" This is equivalence as applied to subject matter, rather than just truth conditions.
- "Orthogonality: outside Q, R is true (false) for the same reasons as within." This is the key principle, which really gets at the intuitive notion that we are genuinely extrapolating P rather than simply gerrymandering a proposition that happens to overlap with P in the Q-region (and then becomes wildly different beyond that point).

Example: The material conditional 'if Q then P' fails the orthogonality condition. Outside the Q region, it is true for the simple reason that Q is false, regardless of P. Compare the visual aid below: 'if Q then P' has truth conditions 'P or ~Q', so would include all the white region in R. The gerrymandering is visible in the fact that the R region would then turn a sharp 'corner' once it left the P & Q region. It should instead extrapolate cleanly as shown.

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Arguing with Eliezer: Part II

[My promised concluding thoughts...]

Clearly our disagreements run too deep to do full justice to them in a mere blog post. But I at least hope I've succeeded in indicating where one might reasonably depart from Eliezer's reductionist line. There are also a couple of ad hominem points which struck me as noteworthy. (See my previous post for real arguments; this is mere commentary.)

One is that our beliefs are shaped in reaction to others. Intelligent non-philosophers typically only come across stupid, woolly-headed non-reductionists. The most prominent public intellectuals are typically scientists of a reductionist bent, like Dawkins, whose most prominent opposition is from anti-intellectual rubes and intellectually bankrupt religious apologists. From a purely sociological perspective, it's no surprise that intelligent people might initially be drawn to the former camp. (I know I was.) But that's no substitute for assessing the strongest arguments -- the ones you've probably never even come across unless you've spent a few years doing academic philosophy, or associate with others who have -- on their merits.

Since Eliezer's posts are mostly directed at a general audience - most of whom have not carefully reflected on their beliefs - I agree with 99% of his criticisms. Folks often commit the mind-projection fallacy, are fooled by an empty dispute that 'feels' substantive, and can be irrationally resistant to perfectly legitimate scientific reductions. These are all important insights (though hardly news to philosophers). But he overgeneralizes -- just as to a man with a hammer, everything looks like a nail.

I think the core problem here is methodological. Eliezer assumes that a debunking explanation of a belief is enough to refute it. Rather than doing the hard work of philosophy -- assessing the arguments for and against P -- he shifts to cognitive science, explaining why I might offer such arguments even if P is false. But this is to commit the genetic fallacy. Any reflective non-reductionist will grant that you can explain all the physical facts (incl. their brain states and vocalizations) without reference to any non-physical facts. Of course. But that doesn't imply anything about whether their belief is justified. Explanation and justification are two completely different things.

Reductionists make this error because they assume that all that stands in need of explanation is the third-personal data of science. Hence (they assume), if you can explain all the empirical data - including the vocalizations of your critics - then there's nothing left for said critics to base their arguments on. This type of genetic fallacy is no fallacy, on this view, because a full empirical explanation exhausts all possible justification.

But this is clearly question-begging, or worse. It assumes an indefensible scientism from the start. Non-reductionists take it as given that there is more than just third-personal empirical data that calls out for explanation. There is the manifest fact of first-personal conscious experience, and the normative facts about what we ought to believe and do, etc. A debunking explanation of why we believe in these phenomena is not sufficient unless one has also successfully debunked the phenomena itself. But that requires actually engaging with non-reductionists and the arguments we offer, rather than simply psychologizing us.

Reductionists, when short on real arguments, like to appeal to meta-arguments, e.g. induction on the historical successes of science. 'There have always been nay-sayers, who questioned the ability of science to explain phenomenon X, and every time they've been proven wrong!' It's a familiar sentiment. But it's also pretty weak. If you bother to look more closely, there are principled reasons to think these cases different. All those examples they point to are instances of third-personal empirical phenomena. I grant that science is supreme in that domain. But, to turn the tables, it's never had any success outside of it. So there's no general reason to think that normativity or first-personal subjective experience are susceptible to purely scientific explanation. So, again, these simplistic meta-arguments are no substitute for the real thing.

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Arguing with Eliezer: Part I

I had the pleasure yesterday of meeting Carl Shulman and Eliezer Yudkowsky (of Overcoming Bias fame) while they were in town, and hashing out some of our philosophical disagreements. It was interesting, because they're both very smart, and Eliezer's starkly materialist/reductionist ideology was shared by my past self. So I'm not entirely unsympathetic. But it was also frustrating in some respects, since he seemed to assume that any disagreement was simply due to a failure to appreciate his basic arguments, rather than a considered judgment that they aren't wholly compelling. So let me discuss a couple of issues in more detail, and attempt to lay out some of the reasons why I've shifted away from his blanket reductionism over the years.

(A) Fundamental Normativity. Eliezer holds that normative terms (e.g. 'should') are reducible to a particular framework of assessment -- roughly, the ultimate norms endorsed by the speaker. He calls this 'objective subjectivism', and it bears some similarity to the 'Objective Moral Relativism' I endorsed back in 2005.

I now find this unsatisfying, for several reasons. (1) The most obvious is that there's nothing really normative here, in the sense of an ideal that potentially outstrips any purely descriptive facts (incl. my current preferences and accepted norms). Though Eliezer wouldn't like to admit it, this is less a reduction than an elimination. Anti-realist maneuvers can save many of the appearances of normative practice, but its deepest aspirations are ultimately rejected. (2) His view implies that many normative disagreements are simply terminological; different people mean different things by the term 'ought', so they're simply talking past each other. This is a popular stance to take, especially among non-philosophers, but it is terribly superficial. See my 'Is Normativity Just Semantics?' for more detail. (3) We can go beyond the impoverished instrumental conception of rationality on which this view depends. Ultimate ends may themselves be assessed as more or less irrational. (I first realized this here.)

(B) Fundamental Mentality. My post on 'Dualist Explanations' outlines the case for property dualism, and defuses typical worries of the scientifically minded. Now, Eliezer seems to think that the causal inefficacy of non-physical phenomenal properties ("irreducible consciousness") is a knock-down argument against them. I once agreed, but again, have since changed my mind. My post, 'Why do you think you're conscious?' addresses this challenge in some detail.

There are some bullets to bite either way. I admit it's a bit odd to think that the words I type are not causally related to the facts I purport to describe. (That's an extreme way of putting it; do follow my above link to put this in perspective.) But, upon reflection, I find this commitment less absurd than denying the manifest reality of first-personal conscious experience (as reductive materialists like Dennett and Eliezer do), or engaging in the metaphysical contortions that non-reductive materialists must (see my 'dualist explanations' post).

(C) Epistemology. Eliezer writes:

When "pure thought" tells you that 1 + 1 = 2, "independently of any experience or observation", you are, in effect, observing your own brain as evidence.

I responded:

It's just fundamentally mistaken to conflate reasoning with "observing your own brain as evidence". For one thing, no amount of mere observation will suffice to bring us to a conclusion, as Lewis Carroll's tortoise taught us. Further, it mistakes content and vehicle. When I judge that p, and subsequently infer q, the basis for my inference is simply p - the proposition itself - and not the psychological fact that I judge that p. I could infer some things from the latter fact too, of course, but that's a very different matter.

In discussion, Eliezer emphasized the demands of (what I call) 'meta-coherence' between our first-order and higher-order beliefs. If you reason from p to q, but further believe that your reasoning in this instance was faulty or unreliable, then this should undermine your belief in q. I agree that reasoning presupposes that one's thought processes are reliable, and a subjectively convincing line of thought may be undermined by showing that the thinker was rationally incapacitated at the time (due to a deceptive drug, say). But presuppositions are not premises. So it simply doesn't follow that the following are equally good arguments:
(1) P, therefore Q
(2) If I were to think about it, I would conclude that Q. Therefore Q.

(Related issues are raised in my post on 'Meta-Evidence'. See also my argument for the inescapability of a priori justification.)

Concluding Remarks. Oops, this is too long already -- I've shifted my concluding thoughts to a new post.

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Constituent vs. World Ontology

Constituent ontologists hold that objects are in some sense 'built up' from metaphysically more basic constituents (e.g. properties). Michael Loux's Principle of Constituent Identity (PCI) states that if X and Y have all the same constituents (in the same arrangement), they must be one and the same object.

But now consider our old friends, duplicates Bob1 and Bob2 in the symmetrical universe. They are qualitatively indiscernible, both intrinsically and even when we take relational properties into account. So, we might wonder, in virtue of what are they distinct? We would seem driven to posit haecceities, primitive 'thisness' or bare identity; one has the fundamental property of being Bob1 - and the other, being Bob2 - and that's what sets the two of them apart. (Robert Adams argues along these lines in his 1979 classic, 'Primitive Thisness and Primitive Identity'.)

I find this a pretty unsatisfying solution, myself. Instead, I take the possibility of "indiscernibles" to show that the whole world is metaphysically prior to its parts. We should reject PCI: there's nothing in the isolated individuals Bob1 and Bob2 that would tell you that they are two in number rather than one and the same. Instead, it is fundamental fact about the world as a whole that it contains two Bobs and not just one.

Actually, even this is not quite right, for the fundamental description of the world shouldn't engage in explicit counting. It's conceivable that there is no uniquely correct answer to the question how many objects there are in the world. For example, Ian Hacking has suggested that there may be no difference between a world containing one iron sphere in a space which curves back on itself vs. two spheres in Euclidian space. We may just have these two ways of describing one and the same possibility. At least, we shouldn't rule this out from the start. Ultimately, though, I think we can reach the conclusion that these are distinct possibilities, via the counterfactual facts (which I'm more tempted to take as primitive). In the one-sphere /curved-space world, it's a fact that if God were to turn the one sphere to gold, then any sphere accessible from this point would also be gold. But the two-sphere world is clearly different: if one were turned to gold, there would remain an iron sphere in the distance.

I do have a curious bullet to bite here nonetheless: you might initially think that there are two possible ways for God to turn an iron sphere to gold in the two-sphere world. He can turn the one sphere to gold, or else the other one. But as a Lewisian, I want to deny this. Possible worlds are fully described by qualitative description: one of two previously indiscernible iron globes is turned to gold. There is no sense to be made of another possibility exactly like this one but where the identities of the globes somehow switch or otherwise differ. (That would be to treat identity as an ontological primitive, which I'm loath to do.)

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Rational Pluralism

I'm inclined towards the view that necessary/a priori truths lack worldly truthmakers, and are instead constituted by the epistemic facts of what it would be ideally rational to believe (truth as the end of inquiry, and all that). One common response people make at this point is to raise the possibility that there is no uniquely rational end-point to philosophical inquiry. Maybe the disputes between Kantians and Consequentialists, mereological universalists and nihilists, etc., would persist even under conditions of ideal rationality. There could be two (or more) equally maximally coherent belief sets. What then?

If the reasons in favour of either view are perfectly balanced, i.e. there really are no possible arguments that would decide the issue one way or another, then it seems intuitively right to me to say that there is no objective fact of the matter which of them is true. Right? (It's not as though we're just incurably ignorant about some contingent matter of fact. The matter under dispute is supposed to be logically necessary, true no matter how the world might turn out, so it really ought to be knowable by reason alone.) So constructivism yields precisely the right result here, it seems to me. It's independently plausible to think that a determinately true philosophical view ought to be determinately rationally superior. So if a philosophical question has no uniquely rational answer, nor does it have any uniquely true answer.

Matters become more complicated if we imagine, not a plurality of views that equally qualify against the standards of ideal rationality, but a plurality of rational standards (each of which leads to a different view, let's say). I'm not sure I can even make sense of this idea. But supposing it were true, should we conclude that there are likewise multiple truth predicates, one for each form of ideal rationality? P is true1 iff P is ideally rational1, true2 iff ideally rational2, etc. It all sounds a bit crazy, but I guess it wouldn't be so bad if there was a large amount of overlap between all the rationalities. We could then supervaluate and say that P is true, simpliciter, iff it qualifies according to all the ideal rationalities. Otherwise, it is just relatively true, depending on which form of rationality you assess it against.

Is that the best way to interpret these scenarios, do you think?

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Expecting Immortality

"The experience of being dead should never be expected to any degree at all, because there is no such experience." So writes David Lewis in 'How Many Lives Has Schrodinger's Cat?' (p.17) But perhaps we can have negative expectations, in the sense of not positively expecting any further experiences.

What if I split, amoeba-style, into two future persons, one of whom is promptly shot? In general, I should split my expectations evenly between my future branches. Perhaps I should anticipate the experiences of each branch, separately. (I do not, of course, experience both lives together, in any mutually-accessible kind of way.) If one branch has no experiences at all - being killed before ever awakening, say - then all there is to anticipate is the other, surviving branch. But if it gets to experience a little before dying, then it would seem one allotment of my expectations should capture precisely this: to experience seeing the bullet approaching (or whatever), and then no more.

This is important because if the "no collapse" (or many-worlds) interpretation of Quantum Mechanics is correct, then we are actually splitting all the time. If you shoot me, there exists some (extremely low intensity) state in the superposition in which the bullet passes right through me. However often I die, there is always some version of me that survives. Should I expect, then, to be immortal? Lewis thinks so (p.19):

Suppose you're fairly sure that there are no collapses, and you're willing to run a risk in the service of truth. Go and wander about on a busy road, preferably a few minutes after closing time. When and if you find yourself still alive, you will have excellent evidence [for the no-collapse view]. If that's not yet enough to convince you, try the experiment a few more times.

What should you expect to happen?
(1) You miraculously emerge unscathed (perhaps the cars pass right through you by some quantum fluke).
(2) You get hit by a car, and then have no further experiences (due to being dead).
(3) You get hit by a car, but then miraculously survive (perhaps your crushed body reassembles itself by some quantum fluke).

On the no collapse view, all these outcomes occur, but (presumably) the second does so with much higher frequency or "intensity". Still, even if the overwhelmingly majority of superimposed states involve your getting hit by a car, you will always have some branch that survives this. So there are always further experiences to anticipate. Does this mean we should never anticipate ending up on a dead branch, i.e. one that has no further experiences?

It's not quite enough to ask whether we should expect to be immortal. On the no-collapse view, we are undoubtedly immortal, in the sense that we will always have some surviving branch. But we also die a lot, in that we have a great many terminating branches! So the real question is whether we should ever expect to die. Can our expectations be distributed over branches that contain no further experiences? Or are they restricted to the survivors only?

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Caring about Time's Reality

Do debates in the metaphysics of time affect what we should care about? If eternalism is true, for example, should we be more or less obsessed with non-present events? If presentism is true, can that justify temporal bias (in favour of the near future, say)?

David Velleman ('So it goes', p.20) writes:

We can't stop the self from seeming to endure, or stop time from seeming to pass, but we can cope with these phenomena better, given the knowledge that they are merely phenomenal...

I have a disconcerting tendency to live different parts of my life all at once -- to relive the past and pre-live the future even while I'm trying to live in the present. And even as I relive my past in a memory, it is at the same time speeding away from me, as there comes bearing down on me a future that I am pre-living in anticipation. It's as if too many parts of my life are on the table at once, and yet somehow they are continually being served up and snatched away like dishes in a restaurant whose wait-staff is too impatient to let me eat...

The realization that I am of the moment -- that is, a momentary part of a temporally extended self -- can remind me to be in the moment.

But why is this? I guess the thought is that if the past no longer exists, our emotional attachment to it may tempt us to imaginatively "bring" it into the present. Eternalism reassures us that the past is safe and sound right where it is, so we need not be so clingy. On the other hand, as a classmate pointed out to me, we may think that the eternal reality of a past event is all the more reason to dwell on it. (I'm more inclined to the view that the metaphysics makes no difference either way. But that may just be because I can't really see what the dispute amounts to -- presentism seems inconceivable to me.)

What of temporal bias? Could "the moving now" better justify the relief we feel when bad events are past? Parfit (R&P, p.180) suggests an argument:

Suppose we allow the metaphor that the scope of 'now' moves into the future. This explains why, of the three attitudes to time, one [the bias towards the near] is irrational, and the other two [biases towards the future, and the present] are rationally required. Pains matter only because of what they are like when they are in the present, or under the scope of 'now'. This is why we must care more about our pains when we are now in pain. 'Now' moves into the future. This is why past pains do not matter. Once pains are past, they will only move away from the scope of 'now'. Things are different with nearness in the future. Time's passage does not justify caring more about the near future since, however distant future pains are, they will come within the scope of 'now'.

But, likewise, however distant past pains are, they have been within the scope of 'now'. Why isn't that enough to make them matter? (After all, concern for the future precludes one from claiming that pains matter only while they are present.) So the mere fact (if it is one) that 'now' moves into the future doesn't explain why past pains do not matter.

One might introduce a "growing block" theory to introduce the needed asymmetry between past and future. On that view, the past exists, whereas the future is still open. But this seems to give precisely the wrong result. Assuming we should care more about existing pains than non-existent ones, the growing-block theorist is committed to favouring the past over the future!

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Could God Pause Time?

Markosian (1993) defends A-theorists (who believe in the objective 'moving present') against the objection that they cannot answer 'How fast does time pass?' He suggests three possible answers:

(1) Measure time against itself. Time thus passes at the trivial rate of one second per second.

(2) Measure time against a non-temporal standard:

If I tell you that Bikila is running at the rate of twelve miles per hour of the pure passage of time, for example, then I have also told you that the pure passage of time is flowing at the rate of one hour for every twelve miles run by Bikila.

(3) Claim that the question involves a category error. Perhaps rate talk essentially "involves a comparison between some normal change and the pure passage of time." (p.843) The pure passage of time itself then has no rate to speak of. But it passes all the same.

These responses all seem woefully inadequate. Especially the third - what does it mean to speak of movement that occurs at no rate? Surely this is just to say that it doesn't literally move after all. The second seems similarly senseless: to move just is to move through time, i.e. to be in different positions at different times. And the first says nothing of substance.

Things that flow may speed up or slow down. Not only does movement entail a rate of movement (contra 3), but it must be possible for this rate to change. If time passes, it must be possible for God to alter its rate of passage - to 'fast forward', 'rewind', or 'pause' the flow of history. But that is incoherent. So time does not pass.

Why is it incoherent? Well, suppose God decides to pause the flow of time for five minutes. How much time has passed? None, for time is frozen. But ex hypothesi five minutes have passed, so time is not frozen. This is a contradiction. (Similarly for the other manipulations, which all involving changing the rate of time's passage to something other than 1 second per second.)

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Quote of the Day

The partisans of time often take it with such Spartan seriousness that they deny existence to virtually all of it

- Donald Williams (1951), 'The Myth of Passage', p.458.

Update: or for a little more substance, p.464:

"Taking place" is not a formality to which an event incidentally submits - it is the event's very being. World history consists of actual concrete happenings in a temporal sequence; it is not necessary or possible that happening should happen to them all over again. The system of the manifold is thus "complete" in something like the technical logical sense, and any attempted addition to it is bound to be either contradictory or supererogatory.

See also: unchanging time and the infinite past.

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Meta-ontology talk

We had some fun discussion at Canterbury last Friday on the question of 'what is existence?'. Philip generously recommended this blog when he introduced me, so I should probably direct any new visitors to the post on which my talk was based: here. Other related posts may be found under the 'metaphysics' category on the left sidebar. (Comments and counterarguments welcome, as always!)

Update: My central argument could be summarized as follows:

1. Ordinary existence claims (e.g. denying that the tooth fairy exists) serve to distinguish between rival possible worlds, whereas ontological disputes instead concern how best to describe a (qualitatively) given world.

2. Substantive inquiry into the nature of the world requires narrowing the possibilities, with the ultimate aim being to discern which possibility has been actualized. (This is arguably the job of empirical science.)

3. So, ontology is lacking in worldly 'substance'.

Meta-ontological projectivism: My positive view is then that ontology (and the rest of philosophy, for that matter) is better understood as a rational construction: it concerns the question of how to carve up the world - or project our concepts onto it - most coherently. The ultimate end (truth) is fixed by the ideals of rationality, rather than any thing in the world. The proposed meta-philosophy in this sense privileges the epistemic over the ontic.

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Metaphysical Production

Is the future in some sense produced or generated from the present? Our intuitive folk metaphysics seems to assume so. The present moment is taken to be metaphysically privileged -- until the laws of nature do their work, generating the 'next' moment out of the raw materials of the present one. This generative process constitutes the passage of time, as the past is literally transformed (in the deepest fabric of its being) into the future. According to this 'presentism', the old times are not simply passed, but wholly replaced.

It's a difficult subject to make sense of. We're used to talking about objects within time, and it's not so clear that our familiar concepts (process, change, replacement), which compare an object between times, can be extended to apply to time itself -- not without regressive appeal to some 'meta-time' during which the manipulation of time-as-an-object occurs. (More here.)

These concerns lead us towards 'Eternalism', or the view that all moments are ontologically on a par. Time is understood to be simply another dimension, not so different from space, and 'now' is an indexical with no more metaphysical import than 'here'.

It seems that this forces us to give up our intuitive beliefs about metaphysical production. If the future already exists, it doesn't need to be generated out of the present. Laws of nature are stripped of their productive power, and instead serve the merely passive purpose of descriptive generalization.

Consider the 'Humean mosaic': the static, 4-d spacetime "loaf" that comprises the entire expanse and (future) history of the universe. The distribution of properties is taken to be fundamental and inexplicable. The way of things is just a brute fact. It just so happens that there are plenty of regularities -- "constant conjunctions" -- to be found in the mosaic. Dropping an object is followed by its falling to the floor. There's not really any deep reason for this (it's just the way the mosaic happens to be drawn), but we can come up with physical "laws" that describe these regularities.

So, what are we to make of all this? Can the luscious garden of common-sense metaphysics be saved? Or should we embrace the desert landscape of the Humean mosaic? I guess David Lewis' project was to show how, with the help of some fancy analytical footwork, we can still assert the truths of common-sense within the desert. Present events still "cause" future ones, and all that. It's just that causation isn't what we thought it was. (Rather than a fundamental notion of generative powers, where the cause brings about its effect, we appeal to a sterile analysis in terms of counterfactual conditionals, which are in turn reduced to facts about other - similarly 'deserted' - Humean mosaics.)

I'm awfully suspicious of that kind of philosophy, as explained in my old post: The Limits of Truth Conditions. I guess I'm assuming some kind of semantic transparency here: we have some idea of what it would take to make our claims true, and the desert just ain't it. I mean, nobody ever read Lewis' On the Plurality of Worlds and thought, "Exactly, that's what I meant when I said that Humphrey could have won the election: just that somewhere out there, in another universe, there's a guy a lot like Humphrey who does win a similar election!"

So I have some secondary questions: Should we be satisfied by crazily counterintuitive analyses, so long as they yield the (truth-conditionally) right results? Why allow that common-sense intuitions are a guide to what's true, but not to what those truths consist in (i.e. what's real)? On the other hand, is it a legitimate objection to Lewis to simply insist, "But that's not what I mean by that term!" -- is meaning so introspectable? How much leeway do we have when assigning truthmakers to a class of claims?

Answers, please!

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Truthmakers of Existence

I highly recommend Ross Cameron's paper on 'Truthmakers and Ontological commitment' [doc]. He rejects the Quinean dogma that allows "serious ontological questions [to be] decided by linguistic facts," and argues instead that a claim like "there are tables" may be literally true without committing us to the inclusion of tables in our fundamental ontology:

Once we allow that the truthmaker for <x exists> can be something other than x this becomes an option on the table: ‘there is a sum of A, B and C’ might be true – but perhaps we don’t need a complex object to make it true: perhaps A, B and C themselves are enough to make this sentence true.

I like it! (Cf. the representational fallacy.) Cameron allows that x exists in such a case, but insists that it does so derivatively, i.e. x doesn't really - fundamentally - exist. This then raises my old worry: what is it to exist fundamentally? This problem is brought out by the fascinating penultimate section of Cameron's paper, when he writes:

I suggested... a picture of the world whereby the only things that really exist are simples, but where we have complex objects as derivative existents. But of course, we can run something like the above story without it being the simples that are taken as fundamental. We could follow Jonathan Schaffer and claim that there is only one fundamental existent – the world – with the proper parts of the world being taken as derivative.

What's the difference? The world is how it is, and this can be described from the perspective of various mereological 'levels' (from the greatest whole to the smallest parts), but - I'm inclined to suggest - at the end of the day there's nothing to decide between them. What would it even mean to privilege one level rather than another with a deeper status of 'being'? What is this difference supposed to consist in, exactly? I just can't get a grasp on what's being claimed here.

If forced to pick one, I'd go with Schaffer's suggestion that the world is fundamental. I don't think that anything else is. And I guess I can't very well claim that everything's derivative; the buck must stop somewhere. So maybe I'm committed to this view after all. I'm not sure, though. I'd really prefer to reject the fundamental/derivative distinction altogether, and simply say that claims are made true by the world - the way things are - without giving ontological priority to any particular aspect of it -- even the unitary entity "the world". In other words, I'd like to get by without any ontology at all (or with a moderately relativistic ontology, may be a better way of putting it). Have I any chance of getting away with this, or is the suggestion simply confused?

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Truth as an Epistemic Construct

BV has an interesting post on the claim that "p is true =df p would be accepted in cognitively ideal conditions." The obvious problem is that being in cognitively ideal conditions would change what's true -- a classic demonstration of the conditional fallacy. Still, it isn't hard to find a work-around for this technicality; simply ask what an ideal spectator would think is true of our world. We might frame this in terms of ideal advice -- what would my idealized self advise me to believe in my actual condition? (Surely that I'm non-ideal, for one thing.) So, one way to overcome the problem is to isolate the idealized vantage point from the actual situation being assessed, i.e. by situating the ideal observer in a different possible world.

BV preempts this response:

But if cognitively ideal conditions are never attained, but are merely possible conditions, then it is difficult to see how the actual truth of any proposition could be identified with what investigators in some merely possible circumstances accept. How can what is actually true be explicated in terms of merely possible judgments?

I take it BV is understanding these ideal agents to be merely investigating their own, non-actual, world. Even then, it doesn't seem so problematic if we've stipulated that their world is a perfect duplicate of ours in respect of the particular details under investigation. (It doesn't seem that bizarre to have the truth be fixed by the best judgment of all possible agents in identical situations.) Note that the normative status of an ideal judgment is unaffected by its existential status. So the only problem would be that their judgments concern unreal things; it's not a judgment's being "merely possible" that's cause for concern, but rather that a judgment is of the merely possible! But this is no longer a problem if the possibility under assessment is a duplicate of ours in the relevant respects, since then the discerned non-actual truth will exactly mirror the actual truth.

Of course, there's a simpler response, which is to have the ideal agents investigating our possible world. Then it's no mystery at all how their (non-actual but ideal) judgments could be relevant to what's actually true. [Granted, you must be part of a world to investigate it using empirical methods, so our ideal observers can't do that. But they can draw implications, i.e. given the totality of experimental data about the actual world, what should we conclude?]

And then there's an even simpler account, which steers well clear of the conditional fallacy by avoiding any kind of conditional analysis at all. Rather than defining epistemic normativity in terms of primitive modality ("what an ideally rational agent would believe"), we may just as well take normativity (ideally rational beliefs) as primitive -- and, if we like, derive modality from there. Epistemicists can then simply define 'p is true' as 'p is epistemically ideal', without appeal to confounding counterfactual situations.

So, I don't think BV has posed an insuperable problem for epistemicists about truth. A bigger problem, to my way of thinking, is that we can clearly conceive of possible worlds where the base facts elude all epistemic grasp. Contingent truths are made true by the world, which is objective / mind-independent / evidence-transcendent. Still, I'm sympathetic to a circumscribed form of epistemic constructivism, concerning necessary (a priori) truths. As I put it here, "philosophical truth just is the ideal limit of a priori inquiry; it does not answer to the sort of independent reality that might sensibly be considered beyond all epistemic reach." After all, it's awfully hard to see what in the world philosophical truths are meant to correspond to. (That big rock over there?) Far more natural to see it as a rational construct, or intangible ideal, that doesn't literally correspond to any mundane thing.

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Verification and Base Facts

Jim Ryan defends a form of verificationism according to which a term (e.g. "zombie") is meaningless if there's no possible evidence that would indicate whether it's being correctly applied. As Jim summarizes the core intuition: "if a person has no idea how to tell whether what he's saying is true, then he doesn't know what he's saying and doesn't mean anything by it."

I'm sympathetic to this, insofar as I think that there is an epistemically transparent component to meaning (i.e. primary intensions). That is, if a person makes a meaningful assertion, then given enough information about the actual world, they will be in a position to tell whether the assertion is true. [This is a loose version of what Chalmers calls "the scrutability of truth".] I think this captures the core of Jim's intuition. But - importantly - this proposal does not require that the given "base facts" be themselves knowable.

Consider the term 'zombie'. This is meaningful, as I know very well how to apply it for any given scenario. Give me a world where the physical base facts are identical to ours, but -- perhaps due to a lack of bridging psycho-physical laws of nature -- no phenomenal properties (i.e. conscious experiences) are found among the psychological base facts. I can tell, here and now (indeed, a priori), that my claim 'Jim is a zombie' is true of that world, comprising those base facts. What I can't tell a priori -- or, perhaps, at all -- is what base facts truly obtain, or which coherent scenario (possible world) is actual.

Jim's verificationism might be understood as starting from the above scrutability thesis, but adding further restrictions on what the contingent "base facts" of reality may consist in. In particular, he requires that the base facts themselves be epistemically accessible, at least in the limited sense that we can envisage possible evidence for and against them. But while this starts in the right place, I think the added restriction goes too far. We should merely require that the base facts be comprehensible, in the sense that someone could understand the difference between scenarios where they do or do not obtain.

Thus, for example, my inability to comprehend the difference between a world with chairs vs. one merely with atoms-arranged-chairwise, (assuming it isn't just a contingent mental block on my part,) leads me to conclude that there is no such difference to be found in reality.

However, I surely can understand the difference in positing any number of spatiotemporally isolated "universes" besides our own, even if causal closure precludes any possible evidence for their existence from reaching me in this universe. Similarly for zombies: we can understand physical properties, and phenomenal properties, and what it would be for one to hold without the other. There's no need for these (even insuperable) epistemological problems to translate into metaphysical ones. We can make sense of reality being "all possible evidence"-transcendent in these cases, so long as it remains rationally apparent precisely which base facts the posited difference consists in.

A final example: Jim uses his verificationism to support "the Humean view" that internal incoherence and factual error are the only possible reasons to revise one's values. There's no sense to be made of a fully-informed and maximally coherent view that somehow remains in "error". For what in the world is left for the idealised agent to be wrong about?

I'm with Jim on this point (and would expand it to all philosophical claims, not just ethical ones). But we don't need his full-blown verificationism to get there. It's enough to note that free-floating moral properties would not make for a comprehensible addition to the base facts of the world. (There's no moral equivalent to the zombie world, e.g. where Hitler acts exactly the same, and yet fails to be immoral.) Add to this our thesis that all truths are rationally scrutable from the base facts, and it follows that any moral truths, in particular, will be accessible in this way.

[Is that right? The argument feels a bit slippery, to me...]

All up, I think my proposed alternative captures the main benefits of Jim's verificationism, without the costs. Suspiciously incomprehensible entities may be rightly discarded, without losing the grip we surely have on familiar physical and phenomenal properties that could conceivably be arranged in undetectable ways.

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