On Philosophers

Eliezer a week ago:

At the frontier of scientific chaos and scientific confusion, you find problems of thinking that are not taught in academic courses, and that have not been reduced to calculation. … It will seem that you must do philosophical thinking in order to sort out the confusion.  But … it is usually not a professional philosopher who wins all the marbles – because it takes intimate involvement with the scientific domain in order to do the philosophical thinking. … There is … [a] place for professional philosophers in the world.  Some problems are so chaotic that there is no established place for them at all in the halls of science.  But those "professional philosophers" would be very, very wise to learn every scrap of relevant-seeming science that they can possibly get their hands on.

Once upon a time all academia was "philosophy", all using the same method of informal argument.  One by one groups focusing on particular topics developed specialized methods, and split off to form new disciplines.  Philosophy is now the "miscellaneous" discipline, the only one left engaging many big hard questions. Philosophers mostly use this method:

Compare intuitions about selected cases with general principles expressed in words.  Discuss wording ambiguities and find extreme case-principle conflicts.  Suggest new wordings for better matches.

Being drawn to big hard questions, I love that philosophers engage those questions.  My main lament is philosophers’ reluctance to calculate; they mostly use their standard method, even when very-well-established more-exact formal models are available.  Two examples:

Born rule in many worlds — physicists mostly punt to philosophers, who use flimsy excuses to declare meaningless the use of specific quantum models to calculate the number of worlds that see particular experimental results.  This leaves them free to settle the question by proposing abstract principles that imply the Born rule.  (At least a few do this semi-formally.)  Two recent workshops here and here, my stuff here.

Rationality of disagreement — Economists studied this since Aumann ’76, but mostly as a theory foil, not to critique human disagreement.  Recently philosophers have written dozens of papers on when it is rational to disagree, basically ignoring the Aumann-started literature.  Some say disagreement is so obviously rational that if models say otherwise, so much the worse for models. Others give flimsy reasons for dismissing model relevance, but mostly I think they can’t be bothered to follow the calculations.  My overview here.

Of course the real problem is that academia discourages interdisciplinary work.  Researchers using one method give too little consideration to people or work using other methods, making it hard to mix or switch methods.  I might well commit similar sins if similarly empowered.

My other laments about philosophers follow from heavy reliance on their main method:  they seem too enamored of words over more formal notation, and they seem to trust their intuitions way too much. 

Besides Eliezer’s comment, this post was also sparked by an enjoyable day I spent last Monday talking to Princeton philosophers:  Prof. Adam Elga for lunch, then guest lecturing for his graduate seminar, attended by Prof. Thomas Kelly and blogger Richard Chappell, and then dinner with Richard, Joshua Harris, and other students. Previously, I’ve spend weeks with Oxford philosophers, including Nick Bostrom, Nicholas Shackel, and Toby Ord, and years with philosophically well-read GMU colleagues (Tyler Cowen is even well published).

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  • Interesting! I agree it was a fun day, though I came away with the opposite lament: that you seemed excessively enamored of formal models, to the point of neglecting insights (or even platitudes) that current formal models do not capture. But so it goes.

  • anonymous

    Paul Graham makes much the same point in the article How to Do Philosophy. His most relevant point is that there will always be a market for impressive-sounding writings which are actually nonsense. Even if the philosophers started using more formal methods (which they’ve been doing since Wittgenstein), critical theorists and the like would just fill in the vacuum.

  • Incidentally, Robin, you may be interested in Vincent Hendrik’s Formal Philosophy, which interviews a number of philosophers who are more enthusiastic about formal methods. Here is an interesting excerpt from Susan Haack:

    Formal methods can be, and sometimes have been, very useful in philosophy; but I don’t believe they are the only useful methods, or even that they enjoy any special privilege. Sometimes a formal approach is just what is needed; but sometimes it is inappropr­iate to the task at hand, sometimes it obliges us artificially to restrict the scope of our questions or the depth of our analysis — and sometimes it is little more than decora­tion, a superficially mathematical or scien­tific gloss on weak or woolly thinking (as the statistical apparatus deployed by social scientists sometimes is). Frege had it just about exactly right: for certain purposes the symbolism of modern logic is more powerful and more precise than natural language; but it is also less flexible and less versatile.

    Personally, I think that formalisms are often overrated, especially since they are easier for non-specialists to misunderstand than plain words are. (See my linked post for more detail.)

    Anonymous – you may be surprised to learn that the culture of analytic philosophy is actually very hostile to gratuitous obscurity, or “impressive-sounding writings”. (Indeed, my old professor Denis Dutton created the Bad Writing Awards to mock the Judith Butlers of the world.) Instead, the ideal is very much for clear, simple writing, so that others might most easily grasp our ideas. We may not always succeed in living up to these ideals, but that’s the culture.

    P.S. I hope I don’t need to point out the false dichotomy between “more formal methods” and “impressive-sounding writings which are actually nonsense.” It is possible to express coherent ideas in clear prose.

  • Richard, I didn’t mean to endorse all formal methods in all contexts, but rather our most well-established formal methods. [I’ve added the phrase “very-well-established” to my claim above.] I’d say quantum mechanics and probability theory count as such methods.

  • “My main lament is philosophers’ reluctance to calculate; they mostly use their standard method, even when more exact formal models are available.”

    Available to whom? Most philosophers, I suspect, are not good enough at math to use the formal models employed by economists or physicists. You are really arguing that philosophers with insufficient mathematical aptitude should avoid writing about topics that intersect with game theory or physics.

  • J.

    For what it’s worth, philosophers are the best at math on the GRE of any non-math-based discipline. My sense is that about half the philosophers I know are good enough to follow most economics without having to look in a textbook for help, and could be good enough to follow all of it if they tried. As for physics, well, I’m not as sure. I had some very technical, formal classes in logic and the philosophy of physics as a grad student, and I’m an ethicist, mind you.

  • my gut says there should be more interdisciplinary approaches, as i think of evolutionary psychology or law and economics, but part of me plays the devil’s advocate and says: if interdisciplinary approaches were so great, more people would do them and would reap the professional benefits. maybe the isolated disciplines make more headway than interdisciplinary approaches. isolated disciplines are like the focused student who becomes a doctor, and interdisciplinary approaches are like the student who dabbled in everything and settled for the easiest available degree and a less illustrious job.

    maybe when the disciplines stop yielding great insights on their own, their members start looking for interdisciplinary approaches to help them reap insights that are closer to what used to be gained by the conventional approaches. the focused doctor has trouble solving a problem with a particular set of patients with a particular set of diseases, and turns to eastern medicine to try to find some useful approaches.

  • Caledonian

    if interdisciplinary approaches were so great, more people would do them and would reap the professional benefits

    They could easily be very fruitful and yet not produce professional benefits – not that I think they are, mind you, but it’s conceivable.

    Philosophy isn’t very fruitful at all, and yet there’s a great deal of professional benefit going around. What is it that philosophers actually strive for? It’s not results, so what is it?

  • anonymous

    Anonymous – you may be surprised to learn that the culture of analytic philosophy is actually very hostile to gratuitous obscurity, or “impressive-sounding writings”.

    You are confirming my point. Analytic philosophy came to prominence in the English-speaking world after Russell and Wittgenstein pointed out that most previous work was hopelessly garbled due to its reliance on ambiguous language. That’s why the basic methods of analytical philosophy provide more integrity than e.g. literary or critical theory.

    There’s no reason not to extend this approach by employing even more rigorous formalisms (provided that they’re applicable and well-understood) if this means that philosophers can recover some focus on the “big questions” that philosophy is often said to address.

  • Caledonian – “What is it that philosophers actually strive for?

    Truth, knowledge, understanding, all that good stuff.

    Philosophy isn’t very fruitful at all

    You keep saying these things. It puzzles me — you’re clearly completely ignorant of the work that goes on in the discipline, so what in the world are these confident pronouncements of yours based on? A priori intuition?

    (I guess I shouldn’t feed the troll but in this case I really am curious…)

  • Raphael A

    What is your evidence for this claim:
    “Others give flimsy reasons for dismissing model relevance, but mostly I think they can’t be bothered to follow the calculations.”

    Do you think this holds of the people you mentioned who have written about disagreement, i.e. Elga, Kelly, Chappell? Looking at the writings of these people, they seem more than willing to engage in formal work. Elga has done philosophy of physics and decision theory stuff. Chappell has a long paper on the Ravens Paradox and took multiple mathematics and computer science courses as an undergraduate. Kelly talks about the Aumann work and seems competent to discuss its technical aspects. Other philosophers who’ve written on disagreement also seem to have technical credentials. Brian Weatherson has done lots of quite technical work in metaphysics and decision theory and David Christensen has written on Dutch Books and Bayesian epistemology.

  • Richard,
    You’re lifting the quality of discussion in the comments significantly. I hope you participate here frequently in the future. You’re also welcome to visit my blog and offer insights and your thoughts on the content there.

  • mitchell porter

    Robin, I just had a look at your two “mangled worlds” papers with a view to answering the first question I have of any many-worlds model, namely, what exactly is a world? Or: given a total wavefunction, how do I figure out what “worlds” it contains? And unfortunately, I am experiencing my usual confusion. In the Found. Phys. paper. section “Many Worlds Interpretation”, you seem to be saying that worlds arise when decoherence occurs. Decoherence does at least determine a projection basis, but you say nothing (that I can see) about how much decoherence is enough to create worlds. It’s not enough to say that if the off-diagonal elements are really small, then decoherence has occurred. They start out big, and there’s one world; they end up small, and now there are many; but when does the transition occur? I do not see how you can define the threshold, except arbitrarily.

  • GNZ

    I’d say self actualization. that and publishing lots of articles and having the respect of one’s peers.

    as to results in the wider sense of things there is an entertainment component and people vote with their money signing up for philosophy courses and buying philosophy books etc. you are here, after-all, discussing these things with people who almost certainly won’t change their mind no matter what you say.

  • “My other laments about philosophers follow from heavy reliance on their main method: they seem too enamored of words over more formal notation, and they seem to trust their intuitions way too much”

    Yes, yes, yes. I am glad somebody else has realized this!

  • Raphael, the basis for my claim includes my long detailed conversations with some. I agree most are smart, have technical training, and write papers with some formal notation and sometimes even prove that theorems follow from axioms. But this is just not the same as taking a model seriously enough to calculate with it, especially when some complexity is involved. And having an ability is not the same as being inclined to exercise that ability in any particular context.

    Mitchell, I don’t see why I need to define a non-arbitrary threshold. Typical coherence levels seem low enough that small variations don’t make much difference.

  • Caledonian

    you are here, after-all, discussing these things with people who almost certainly won’t change their mind no matter what you say.

    I’m always happy to help people make fools of themselves.

    And it is useful to recognize who will be first against the wall when the revolution comes.

  • mitchell porter

    Robin, what sort of entity is a world, then? For boundary cases, where the threshold is set will determine the presence or absence of worlds. And since you and I are supposed to be inhabiting a world, it is not a concept we can treat as a mere approximation. Perhaps your derivation of the Born rule doesn’t need a rigorously exact theory of what a world is, but if the concept is truly supposed to pertain to reality, it must eventually be given an exact formulation.

  • Mitchell, we make use of many concepts without non-arbitrary exact definitions: galaxy, liquid, surface, etc.

  • DL

    Caledonian, you forgot to mention how humble you are too!

  • Caledonian, what makes you think there will be a revolution?

    Some of you might be tired of my low opinion of philosophy, but if it could benefit from the work of physicists, does Robin think other fields would likewise derive benefits from that of philosophy?

  • Also, Richard, what are some prime examples of “insights (or even platitudes) that current formal models do not capture”?

  • mitchell porter

    Robin, there is no paradox if those concepts are vague. But a “world”, as you are using it in these papers, is a sort of maximal domain in which a copy of an observer exists. The number of such worlds tells you the number of such observers. If you assert that there is no objective answer to that question, then you are saying that whether or not a particular observer exists is a matter of convention. This amounts to saying that there is no fact, no yes-or-no answer, to the question of whether you exist. Which is false, I hope you will agree. But that then implies that it is also an objective matter as to whether the quantum world that contains you exists. Which in turn implies that a vague concept of quantum world cannot be enough. It must either become exact, or some entirely other conceptual framework must be found.

  • GNZ

    > who will be first against the wall

    I don’t really see materialists putting useless philosophers against the wall. Maybe some pointing and laughing instead. Of course you have started that already.

  • Grant

    I admit to not having read a lot of philosophy, but the (mostly older) stuff I have read left me with the same impression Robin expressed here:

    “My other laments about philosophers follow from heavy reliance on their main method: they seem too enamored of words over more formal notation, and they seem to trust their intuitions way too much”

    One problem with words is that their meaning changes over time and with different readers. Formal concepts and symbols are, generally speaking, much less mutable. Much of the disagreement in philosophy that I’ve read seemed to originate from semantical disagreements.

  • Mitchell, at some moments you exist, but before you were born and after you die you don’t exist. But there are only arbitrary ways to define the exact moment when you are born or die.

  • michael vassar

    It seems to me that formalisms are mostly harmful because typically, as actually used, they validly convey the rigor and certainty of a particular well specified claim, but are then typically paraphrased into informal language in a manner which pretends to transfer the rigor of that conclusion to a much more general but vaguely analogous conclusion with actual relevance to people’s lives and decisions. Without this translation, such formalisms remain, outside of physics, basically pointless, but academic status doesn’t seem to be awarded for rigor, care, and honesty in translation, but only for the elaboration and cleverness displayed in the creation of the formalism.

  • Michael

    Dr. Hanson,

    When you claim ” they seem too enamored of words over more formal notation, and they seem to trust their intuitions way too much,” would you include even Drs. Stalnaker, Williamson, Bostrom, van Fraasen, Tennant, etc., here?

  • mitchell porter

    Robin: there are only arbitrary ways to define the exact moment when you are born or die

    Oh, come on! First of all, it’s the period in between that we’re concerned with. That’s when you’re a functioning “observer”, and that is the part where it would be nonsense to say, “There’s not actually any fact about the number of copies of me that exist in the multiverse. It depends on where you set an arbitrary cut-off.” Again, according to the hypothesis, you right now are one of those copies, and because you definitely exist here and now, your existence and the existence of this world cannot simply be a matter of definitional convention, dependent on where we set a decoherence threshold parameter.

    I also think you underestimate the objectivity with which the beginning and the end of your existence in time can be defined. The principle is the same: if you are aware of these words, then at that moment there is some sense in which you exist, categorically and absolutely. This in turn implies that there is some quite objective criterion of personal existence available. Consider the idea of a “neural correlate of consciousness”. One might say: there’s a person there, if and only if that neural correlate is there. I concede that even here, multiple definitions will be possible: one would be, the person exists if and only if the neural correlate is there and it is in a state of consciousness; another would be counterfactual, the person exists if the neural correlate could become conscious. Personhood is a complex concept, and unless its ontological basis proves to be much simpler than one would presently expect, there will be multiple objective thresholds at which one might draw the line between person and not-a-person, just as there are degrees of consciousness, a variety of mental faculties which may or may not be possessed, and so forth.

    But I bring up all those complications only to demonstrate that there is no excuse anywhere for treating things as elemental as “existence” and “awareness of existing” as being on a par with those fuzzy, conventionally defined concepts. If your theory is fuzzy about them, it means the theory isn’t complete – that’s all.

  • mitchell porter

    I find that I said this all already, five years ago.

  • Unknown

    Mitchell, all possible concepts are vague, and the vaguest of all is “existence.” If you disagree, show some examples of well-defined concepts. (Mathematics and logic do not provide examples, as you will see after thinking about it for a bit.)

  • mitchell porter

    Unknown, above all I am saying that realities are not vague. There is nothing at all mysterious about a concept whose vagueness arises from its being about highly complicated entities. To exactly define the scope of such a concept will itself typically be a highly complicated matter, because there are so many cases to be dealt with.

    But “existence” is not in any way a vague concept. Why would you think it is – because it applies to everything? (Everything that exists, at least.) Because it has no properties of its own? A vague concept is one whose reference is underdetermined. But intensionally speaking, the scope of “existence” should be crystal clear, even if it is hard to define in a noncircular way: X exists if and only if X is part of reality – reality being everything that exists. If I say there’s an elephant outside your window, you don’t puzzle yourself over what I mean by the “is” in “There is an elephant…”, you proceed immediately to judge the truth of my utterance by referring to reality itself, perhaps by looking out the window.

    In any case, as interesting as the discussion about the nature of existence is (is it a property, is it something else, how do we know of it), it is not necessary to have that discussion to make my point. As an individual observer, just about the most elementary thing you can know about reality is that it is there. That something exists is the most epistemically basic fact there is – followed by the fact that it’s you (whatever you are) that knows this. A theory of your existence which implicitly asserts that there is no such fact would be wrong, but any theory which makes your existence a matter of convention is already such a theory, and yet that is what we have if the existence of quantum worlds is held to be determined by arbitrary convention.

  • Unknown

    Mitchell, your claim “any theory which makes your existence a matter of convention is already such a theory” is not evident and needs to be established.

    If I see someone who is bald, saying that the word “bald” is vague and cannot be precisely defined is not saying that the bald person does not exist, nor that he is not bald. It is not saying that “there is no such fact.” It it simply saying that he is in fact bald, but his baldness is something vague.

    In the same way, there is no reason not to admit that I exist, but my existence is something vague.

  • One area where no formal models can even capture all the platitudes is in the theory of truth. Every meaningful sentence is either true or false (but not both); we can express meaningful sentences containing the words “true” and “false”; and it’s certainly possible for a card to have the following two sentences written on opposite sides: “the sentence on the opposite side of this card is true” and “the sentence on the opposite side of this card is false”. There has been a lot of work done in recent years to improve formal models of this sort of stuff (look at the work of JC Beall, Kevin Scharp, Hartry Field, Anil Gupta, Graham Priest, and others) but none of them really work yet.

    Even in areas where the formal models are very well developed and seem to do a good job of capturing the ordinary notions are still generally full of problems – there’s a recent paper by David Baker pointing out that recent derivations of the Born rule from the many-worlds interpretation are circular in the way they presuppose decoherence; there’s lots of work in Bayesian epistemology pointing out the ways in which particular models assume all sorts of things, like logical omniscience and omniscience about one’s own mind.

    Someone earlier in the thread said that words are apt to change meaning, while formal symbolism is not. I would say that in fact that in many cases, the situation for formal symbolism is far worse – there are far too many distinct axiomatic theories that aim to discuss the same concept, and use very similar notation, so that it’s very easy to interpret a formula in one system, when it’s meant to be interpreted in the other. Even consider the confusion caused in pure mathematics by different conventions of whether rings are commutative and have identity, or whether topological spaces are compact or Hausdorff. The important thing is to be really careful and clear about what you’re talking about, and to do this right, we often need to use an appropriate combination of formal methods and informal language. We can get a very precise grip on something by using formal methods, but informal language is generally much closer to the thing that we actually want to talk about. Our aim is to somehow bridge the gap, so that we can get a very precise grip on the thing we actually want to talk about.

    • themusicgod1

      Anyone have a link for the confusion in pure mathematics about the rings part? Did this get resolved since or something?

  • mitchell porter

    Unknown, I feel like I really shouldn’t have to go through all these contortions and byways to make a very simple point. So let me first try, one more time, to say it very simply: You exist. You know you exist. According to many worlds, you are part of a “world”. Since you unquestionably do exist, the world that contains you must also exist just as absolutely as you do. Therefore, a theory which shrugs its shoulders rather than be exact about the existence of worlds is, at best, incomplete (and at worst, it is entirely wrong, along with the whole many-worlds notion).

    Now back to details…

    You bring up a paradigm example of a vague property, baldness. But there is a big difference between attributing a vague property to something whose overall existence is not in doubt, and saying that the very existence of a thing “is vague”. I’m not even sure what you mean by the latter. Are you saying that some of your properties are vague? But that’s not what this is about. Let’s distinguish between thatness and whatness; the fact of your existence, and the nature of your existence. That you are, that you exist, should not be in doubt. What you are, your nature as an existing being, the collection of all your properties, is much more in doubt. It’s complicated, open-ended, there is plenty of scope to attribute to you properties which are vague because they are complex and underspecified, as I wrote earlier. Baldness is very definitely a property of that kind.

    Now what does it mean to talk about the existence of a vaguely defined object? It means that for some cases, the existence or nonexistence of the object will vary across specific refinements of the definition (refinement to the point of exactness, i.e. to the point of offering an exact yes-or-no answer to the question ‘Is it there?’ in all possible worlds). Already this means that there must be some definition of “you” which is not vague, because there is at least one sense in which you unquestionably exist, namely, the sense in which you are a locus of awareness. (For the sake of argument I assume I am not talking with a zombie or a hallucination.) Your existence, in that sense, cannot be dependent on a definition. Your existence as a locus of awareness is a certainty, regardless of what uncertainties there may be regarding other aspects of your ultimate nature.

    But this also applies to all your copies. If they exist, they exist unequivocally, in definite quantity. And since there is one world per copy – since a copy owes its existence to being part of a “quantum world” – then worlds too must exist just as unequivocally. And so an ultimate theory cannot still treat the concept of world as a merely heuristic concept that can remain vague. It must become “sharp”, exact, in the final reckoning.

  • Caledonian

    mitchell porter, can you explain what it is that you mean by ‘existence’?

    When you say things like:

    So let me first try, one more time, to say it very simply: You exist. You know you exist.

    What is it that you’re asserting Unknown knows?

  • Unknown

    Mitchell, I have no doubt that I exist. I also have no doubt that certain people are bald. You are confusing doubtful claims with vague claims. A claim can be vague but certain, or a claim can be distinct (to a certain degree; my point is that absolute distinctness is impossible) but doubtful.

    When I say that someone is bald, I may be certain or uncertain. Either way, the claim is vague.

    When I say that I exist, I am very certain. In this case, according to me, the claim is certainly also very vague.

    Once again, if you say that this claim is distinct, please offer an exact definition of existence that clearly manifests those and only those things which are included in existence. You have not yet done this, saying that it is not easy to do without being circular. If so, this reveals that the idea of existence is extremely vague, even if very certain.

  • mitchell porter

    Before I get lost in these semantic and epistemic complexities, I will say once again what the problem is.

    We are endeavoring to interpret the wavefunctions or state vectors of quantum mechanics: to form a hypothesis about the reality they describe. The hypothesis is: before decoherence there is one “quantum world”, after decoherence there are many quantum worlds. As the difference between “one world” and “more than one world” is discontinuous, but the process of decoherence is continuous, with no sharp boundary between before and after, I asked exactly where the transition from one world to more than one world occurs. The reply was that that is not an issue, since the answer would make no difference to the argument in the papers. I conceded that it makes no difference to this particular argument, but the issue itself must be faced; the existence of these worlds, if they are to be taken seriously, must be an objective matter.

    Somehow, having attempted to argue for that last proposition, I find myself being asked to define what I mean by “existence”, to accept that someone’s existence can be “vague”, and who knows what else is going to come up. I accept the desirability of trying to elucidate fundamental concepts as thoroughly as possible. But can I first ask: If a person said that according to their theory of the universe, at one time you have one of something, and later on you have many copies of that same thing, but there’s no particular moment in time when the one becomes the many, and that doesn’t matter because the something only has a vague, fuzzy existence… wouldn’t you think that the theory might have a few problems, or at least be missing a part?

    Everything I have said about worlds, and observers in worlds, and about the certainty of one’s own existence as an individual observer, has been meant to drive that home. That chain of relationships is the detailed reason why it is unacceptable to have a blase attitude towards the conditions of existence of quantum worlds. They must be regarded as existing or not existing, in a completely objective, absolute, non-relative way, or the concept becomes a nonsense, because worlds must play the role of hosting entities whose existence is definitely not vague or relative, namely, us.

    Does no-one understand or sympathize with this line of thought?

    I will get on with the philosophy in a moment. But I ask that those of you who may find yourselves in a protracted debate with me over these tangential questions, please consider anew the foregoing argument and ask yourself whether it is desirable or even possible to settle for a vague notion of “world”, given the theoretical burden it has to bear.

    Caledonian asks what I mean by “existence”. I confess that I am unable to define it without using a synonym, which is not much of a definition. There may be quite a few similar basic indefinables, which we nonetheless manage to talk about; “negation” may be another example. It seems that all I can do is talk about it, and hope some recognition dawns. I know I already have a disagreement with Caledonian in this matter, because earlier this month he wrote here that existence is relative and depends on the possibility of interaction, something I would never say, because it confuses existence per se with something like knowability – the epistemic grounds whereby one observer may assert of one thing that it does indeed exist. We who live now, our existence was not knowable to anyone who lived a thousand years ago. Nonetheless, we do exist, here and now, and it is a fallacy to relativize our existence, and say “we exist for each other, but we don’t exist for those people in the past”. It is a basic confusion of knowability with reality.

    Now, Unknown, what am I to do with you? Your line is that existence is a vague concept because I cannot define it without being circular, or that I cannot define it in a way which offers a clear decision procedure for existence. My line would be that we all know perfectly well what “existence” refers to – the property of being there, the property of being a part of reality, the property of not being nonexistent – but that the metaphysical depths of its nature are not so obvious. Again, one is constantly making implicit judgements about what does and does not exist. Does al Qaeda exist? Does Xenu exist? Does the special discount on milk at the corner store still exist? Existential judgements are ubiquitous in human thought. We all possess a basic facility with the concept. Does the inability to crisply define it or place it in an ontological scheme mean that one only has a vague concept of existence? I don’t think so, because I think the criterion of vagueness in a concept is that its referent, the specific thing which it designates, is underdetermined (i.e. there are several different things it might be referring to), not that the nature of the referent remains incompletely specified. I think the particular referent of the human concept of existence is unambiguously known, but the nature of that referent may be obscure to the human mind. But this is a complicated matter.

    And one more time: this metaphysics is an interesting and even vital topic, but it is somewhat of a tangent from the main issue, which is the meaning of “world” in many worlds.

  • mitchell porter

    I made a lengthy reply here yesterday. I even saw it go through. Half of it was about the real issue (the quantum worlds), half of it about these conceptual tangents. It’s gone now and I didn’t save a copy. I’ll wait a few hours to see if anyone happens to have preserved it, and then I’ll do it again from scratch.

  • mitchell porter

    OK, I just checked my email and I see it was rejected as too long and insufficiently relevant. Very well. If anyone wants to see what I said (Caledonian and Unknown, I suppose this means you), mail me at mitchtemporarily@hotmail.com.

  • While I agree with the sentiment about the typical philosopher’s over-reliance on intuition and the need for formalization and calculation when possible, nonetheless many sub-disciplines of philosophy, such as epistemology, philosophy of science and (der) logic use formal methods regularly.

    I apologize for going all laundry list on you guys, but one has just to look at the the many philosophical journals (The British Journal for the Philosophy of Science, Erkenntnis, Journal of Symbolic Logic, etc.), conferences (e.g. Formal Epistemology Workshop) professional associations (The Society for Exact Philosophy, Association for Symbolic Logic, etc.) and books that feature formal treatments of philosophical problems. Moreover, examples abound of philosophers using, and better, contributing to, Bayesian networks (Williamson, Glymour, Bayesian statistics(Seidenfeld), formal learning theory (Putnam, Kelly), set theory (Dana Scott and many others), and more formal subjects. Hell, there is even a move toward experimental philosophy for the more naturalistically inclined.

    See this online copy of Patric Suppes’ Representation and Invariance of Scientific Structures for one approach to formal philosophy. Suppes is an excellent example of a formally-minded philosopher that is responsible for many innovations in fields outside the discipline.

    Best Regards.

  • Also relevant: Philosophy, Science, and Method— a new blog dedicated to promoting philosophy that maintains significant contact with mathematics or science.

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