Problems with Jim's Platonic Account

Much of what I have to say probably reflects the fact that most of Jim's account eludes my understanding. (Perhaps I can't quite see how it works!). Sorry for the length - believe it or not, this is the condensed version of my notes. Of course, I don’t expect anyone to read it all :)

TEs as visualizable

Brown takes it to be a virtue of his account that it can accommodate the phenomenology of thought-experimentation. (I'll say more about this phenomenological stuff later.) In particular, he thinks it nicely captures the idea of TEs being 'visualizable'. He even seems to claim that visualization is a necessary condition of any TE, since he rules out TEs that don't involve "a picturable state of affairs". (LAB, p. 18) Presumably, 'visualization' must mean something like: pictorial-mental representation via the 'mind's eye'. Does this apply to all TEs? To what degree/extent must a TE be visualizable? Does this condition carry over to TEs outside of natural science? Brown's account purports to restrict itself to TEs in natural science, but he often appeals to examples outside of natural science, e.g. Searle's Chinese Room, Thompson's Violinist, Jackson's Mary - and not merely for illustrative purposes. They're each examples of easily visualizable scenarios, so he must think the visualization-condition carries over to TEs in philosophy, too. But that's not clear at all; and it's even less clear why a good TE in philosophy must be visualizable, especially since some of the best TEs in philosophy hinge on making a conceptual point. In what meaningful sense is (e.g.) Spinoza's perspective sub specie aeternitatis or Nagel's 'view from nowhere' (which could surely constitute key elements of a good TE) visualizable? And why is its visualization even relevant? Also, given much of what Jim goes on to say, it's deeply unclear how the visualization-condition is supposed to apply. For instance, he points out that some of the best TEs - e.g. Maxwell's Demon - depict a "contradictory situation." As he puts it: "Though the whole situation is contradictory, the [TE] works..." Borrowing from Norton, it would take an "epistemic miracle" to see or visualize a contradictory (i.e. impossible!) situation. At minimum, we need a clearer account of (a) what we're 'seeing' in a contradictory situation, and (b) the degree to which TEs must be visualizable - one that doesn't imply that we can visualize impossible situations, e.g. a round-squares floating around in Plato's (non-spatial) Heaven. :)

TEs, Thought, and the 'External World'

Jim draws a distinction between a TE and a "psycho-linguistic experiment". (LAB, pp. 15-16) The latter, he thinks, is more accurately characterized as a "real experiment" or "empirical experiment [EE] about thought itself." TEs are about "the external world and thinking is the method of learning something about it." This entails (as Jim admits) that there can be no TEs about thought itself. But this can't be right. Indeed, Jim himself cites a clear counterexample without recognizing it as such. On p. 27, he claims that Searle's Chinese Room is a TE "which has to do with the nature of thought itself"! Searle's Chinese Room is a TE about thought itself which purports to show (roughly) that thought is not (mere) computation. Thus, if he's right about Searle's Chinese Room, his distinction between TEs and psycho-linguistic experiments (and EEs in general) is kaput. Perhaps he means only that TEs in natural science can't be "about thought itself." But that doesn't hold up either. First, unless we're substance dualists, the nature of thought is at least partly within the epistemic ambit of scientific inquiry, and it's surely part of "the external world." If so, nothing rules out the possibility of natural-science-TEs about thought itself. So the distinction is untenable as it stands.

Issues with the Taxonomy and Jim's Critique of Norton's Argument Account.

1. Jim's taxonomy seems to imply that while there are Destructive-Direct TEs (i.e. Platonic TEs), there can't be any Destructive-Mediative TEs. But that's implausible. If Mediative TEs simply "facilitate understanding", or serve as a kind of "midwife" guiding us from a background theory to a new conclusion, or (sometimes) play a more "instrumental role" (which, incidentally, he never explains very clearly), then why must they be only constructive? Ditto for Conjectural TEs. The taxonomy doesn't seem to allow for Destructive-Conjectural TEs, but without justification. Even if we're not starting out with any "well-articulated background theory", by establishing a thought-experimental phenomenon P that requires explanation and conjecturing some explanation E of P, we seem to be ruling out other alternative explanations of P, at least those that are incompatible with E. But this 'ruling out' is clearly destructive. Indeed, we can say more than this: in an important sense, every constructive TE is ipso facto a destructive TE. If I can establish that P via some TE, and if P is incompatible with Q, with the result that Q has been ruled out, isn't this a destructive (as well as constructive) result?
2. Jim claims that Mediative TEs don't do any supportive/evidential work. This is mainly why he thinks that Norton's argument account can't accommodate them. Rather, they play a psychological (rather than justificatory) role, in that they provide (where necessary) the "psychological help" needed to facilitate understanding or acceptance of some theory T. But why can't a Mediative TE provide at least indirect support for T by (e.g.) showing it in a better, clearer, more plausible-looking setting? It seems like a persuasive tool - it's not just psychologically useful, illustrative filler. Indeed, they might function very much like arguments by analogy - or more generally, as appeals to consistency across structurally-similar cases. As Jim says, "a mediative [TE] might illustrate some otherwise highly counterintuitive aspect of the theory thereby making it seem more palatable..." (LAB, p. 35) The idea is that if you accept T in a more plausible-looking or intuition-friendly setting (i.e., the setting as depicted in the mediative TE), then - on pain of inconsistency - you should accept T in a less plausible-looking (etc.) settings, unless there's some relevant substantive/structural difference. Also, if a Mediative TE succeeds in showing something, shouldn't it be possible to show how it shows it, i.e. to reconstruct as an argument?
3. I'm having a hard time making sense of Conjectural TEs, and why Jim thinks they pose a problem for Norton's account. First, he claims that Conjectural TEs don't start with some theory but end with one. What does this mean exactly? Surely any TE, to make sense at all, must presuppose some background theory or another. Second, I think Norton's right in claiming that a Conjectural TE is an inference to the best explanation (or perhaps more accurately, that they end with a inference to the best explanation). After all, it posits some thought-experimental phenomenon and offers an explanation of that phenomenon, i.e. a theory which (purportedly) best explains that phenomenon.
4. One of Jim's objections to Norton's account says that even if it were possible to reconstruct any TE as an argument (and so far, I haven't found any good reason to think it isn't - anyone disagree here?), it doesn't accurately reflect the actual psychology or phenomenology of thought-experimenters. For starters, this does nothing to harm Norton's account of the justification and evaluation of TEs (i.e. in terms of arguments). Second, Norton doesn't seem to be claiming that his view is an account of what's actually going on at the level of conscious awareness whilst thought-experimenters are thought-experimenting. Third, Norton's view is compatible with thought-experimentation involving tacit argumentation, even if it's not explicit during the conscious experience of thought-experimentation. Fourth, Jim's own account of what's going on in no way corresponds to or reflects my own phenomenology vis-a-vis thought-experimentation. Crucially, in developing TEs, I don't experience or take myself to be 'seeing the laws of nature' - at minimum, I take myself to be defending or criticizing some theory via a non-actual but possible case (otherwise, I wouldn't introduce my TEs by saying, "Suppose that...", etc.) which I take to show what I'm trying to show by developing such a case. Of course, as I just pointed in connection with Norton, Jim might be right here: perhaps at a deeper level, some sort of tacit Platonic seeing is going on. Who knows! The point is that if it's unfair to criticize Jim on such grounds (and I think it is), it's unfair to criticize Norton on the same grounds. So, we shouldn't criticize either account on the ground it doesn't match up with one's conscious awareness of thought-experimentation (let alone one's interpretation of such goings-on). Finally, there are clearly several paths to the same destination: even if Jim is right that some (many?) thought-experimenters don't thought-experiment a la Norton, it doesn't follow that no thought-experimenter does - let alone that no thought-experimenter should.

The Mystery of Platonic Perception

Jim admits that Platonic perception ('P-perception' for short) is mysterious, but I don't think he appreciates the extent to which this undermines the plausibility of his Platonic account of TEs. Obviously, a good deal of what I'll say here (which isn't very much) should be taken as tentative/provisional, mainly because I just don't have a clue what I'm being asked to consider (which is also why I can't say very much about it!).

This last point is crucial, and that's where I'll start. If there is such a thing as P-perception, Jim doesn't tell us anything about it. No attempt is made to offer a positive account of exactly what it is, how it works, and how (let alone why) it succeeds/fails. It's frequently - albeit loosely and spuriously - associated with comparatively less mysterious/unpalatable notions, such as "grasping", "intuiting", "understanding" and the like. Not only are these latter notions in no way equivalent (conceptually or ontologically) to "perceiving" or "seeing", Jim doesn't show us how they're connected to (much less how we can understand P-perception on the basis of) such notions. If all he means is (say) intuition, why talk in terms of "perception" at all? To invoke talk of "perceiving" abstract objects borders on a category mistake: Jim might be right that knowledge doesn't require a causal connection to some physical object or property; but perception - at least in the sense that we even remotely understand and use in our literal, philosophically serious talk - clearly does. And that's why I'm at a loss as to why "perception" is invoked at all.

Jim argues that the mystery of P-perception is acceptable because it's analogous to the 'mystery' of "ordinary [i.e. sensory] perception". If we accept it in the case of the latter, we should have no qualms about accepting in the case of the former. I think Norton does a great job criticizing this argument; also, Joey raises some interesting points of his own in addition to summarizing Norton's position on the matter. So I won't rehearse these points in detail - see pp. 358-365 for Norton's arguments (and see also Joey's post!). Instead, I'll try to develop a few points of my own.

Jim claims that ordinary perception and P-perception are equally mysterious: "...the perception of abstract laws of nature is certainly [!] no more mysterious than that [i.e. belief about the object seen, the 'second' part of ordinary perception]." (LAB, 108) I doubt that many cognitive psychologists, neuroscientists, and philosophers of mind would follow Jim in his certainty here. We don't have a complete, fully articulated theory that commands universal consensus, but to claim that it's a "complete mystery" is absolutely incredible. Moreover, at least we understand part of the story; not so for P-perception: we don't understand any part. Nothing whatsoever. Indeed, P-perception is almost 'Meta-Mysterious': it's not even clear what we don't have any understanding of.

But let's suppose Jim's right about both types being 'equally mysterious'. What could we conclude from this? We couldn't conclude that this provides any positive support for, or even makes room for rational and principled acceptance of, P-perception. If the 'equal mystery' claim holds, we should deeply suspicious of both. Salve double-negation, two wrongs don't make a right (and not just in ethics). We appreciate this fact in other contexts. Consider, e.g., one of Plantinga's (bad) arguments for the rational acceptability of Christian faith: Do we have conclusive grounds for believing in the existence of minds other than our own? Suppose our grounds for the one (belief in God) were rationally/evidentially equivalent to our grounds for the other (belief in other minds). What could we conclude from this? Could we conclude that Christian faith is thereby vindicated, because it's just as bad - rationally/evidentially - as belief in other minds? Not at all. You can't show that one thing is good by showing that something else is just as bad as what you claim is good. In the same way, if ordinary perception is just as mysterious as P-perception, then so much the worse for both. Fortunately, there are good reasons to reject the 'equal-mystery' thesis.

Norton does a good job in showing why it's completely mysterious not only what P-perception is, but how/why it succeeds/fails. But I want to point something out about justification and evaluation in particular. Suppose Jim is right that in (successful) thought-experimentation, Platonic Seers can see the laws of nature. What if I can't see what they see? Suppose I'm lame, uninsightful - 'Platonically challenged', so to speak. I just don't have the 'gift'. Why should I trust the alleged Seer? It seems to me that I'm perfectly entitled to say:

Good for you! Now show it in a way that's accessible to all of us. Surely, if what you claim is true; if what you claim accurately represents how the world is, it must be possible to give reasons for why this is so. It must be possible, in other words, to give us a sound or inductively strong argument that shows whatever it is you claim that you have 'seen' with your Platonic 'eyes'. After all, how else can we rationally assess (let alone accept) your claim - we who do not See as you do, O Great Seer?

Another way to put the point: when the Seer comes back down in the Cave, he shouldn't expect us to merely take his word for it. If he can't do what we ask of him, why should we believe anything that he says?

An Argument for P-Perception?

In closing, let me gesture at a possible defense of P-perception. I'm not sure that it works, but it makes at least the possibility of P-perception more digestible. In Knowledge and the Flow of Information, Fred Dretske defends a distinction between sensory perception (i.e. the perception of objects) and cognitive perception (i.e. the perception of facts). Very roughly (omitting details), while one S-perceives such objects as cats and mats, one C-perceives that the cat is on the mat - the latter involves not merely objects, but a state of affairs (i.e. the cat's being on the mat) and a relation (i.e. x is on y [or something similar]), which constitute a fact (i.e. that the cat is on the mat). Again, ignore the details and just reflect on whether C-perception is plausible. If it is, then it somehow seems to involve, at least in part, the perception of abstracta. Why? Well, plausibly, states of affairs and relations (or at least the latter) are abstracta. If so, then C-perception is (at least partly) the perception of abstracta. But if C-perception makes sense, then - contra my claim above about the inextricable link between physical causation and perception - this opens the (metaphysical) door to P-perception. Moreover, it seems very plausible that the candidate objects of P-perception - namely laws of nature - are facts of some kind.

A Few Notes on Platonic Perception

I want to note straight out that I, like Jim Brown, am deeply sympathetic to Platonism in mathematics. I want to be able to say that we can have a priori knowledge of mathematical truths, and it strikes me as tempting to say that we attain this knowledge through a process that is somehow analogous to perception. How would we come to know mathematical truths that cannot be given in experience, except by somehow ‘glimpsing’ them with another faculty? Brown thinks this is precisely what is going on, even if no account of what this faculty of mathematical perception is or how it works can be given. Now, on Brown’s view we can sometimes ‘glimpse’ the laws of nature in much the same way that we ‘glimpse’ that 2 and 2 are 4. And indeed it is not readily apparent why we should find Platonism a plausible view in the mathematical case but not in other cases of (apparent) a priori knowledge.

Now, one might object that we just cannot understand what it is to see abstract entities such as laws, numbers, sets etc. And Brown is more or less willing to concede that we really don’t understand how this sort of platonic perception works. Thus the analogy between platonic and ordinary perception breaks down. However, Brown doubts that this can really stand as an objection to his view. He points out that we really don’t have an adequate understanding of how everyday perception works either. So critics who demand a full account of how we make epistemic contact with abstract entities are simply demanding too much from the Platonist. Moreover, the mere fact that we don’t have such an understanding is not by itself evidence against the existence of this kind of perception (doubtless a lot of things exist of which we don’t have an adequate understanding).

John Norton thinks this is an unsatisfactory response to the worries of the empirically minded. Brown’s account allows that platonic thought experiments (even very good ones) can sometimes lead us into error. Such thought experiments afford apparent glimpses of the true laws of nature, but in some cases this is an illusory appearance. What appears to be an instance of a priori knowledge of natural laws can turn out to be no knowledge at all. Brown suggests that we need not be troubled by the fallibility of platonic perception any more than we are troubled by the fallibility of ordinary perception. The argument from illusion is hardly taken seriously in the latter case, so why should it be in the former.

Norton thinks this overlooks a serious disanology between the two cases, which he summarizes as below:

(3A) Ordinary perception is well understood insofar as it governed by an array of familiar regularities. They make the success or failure of ordinary perception controllable and intelligible in all but exceptional cases.

(3B) The mechanism of perception of Platonic laws is essentially completely mysterious. We have no understanding of why this perception succeeds when it succeeds and fails when it fails. ( "Are Thought Experiments Just What You Thought" 359-60)

I think it is difficult to deny 3A, without opening ourselves up to a somewhat unsavory skepticism about sense perception. We may not ultimately understand all the mechanisms at play in ordinary perception, but surely we know something about the conditions under which it is reasonable to trust our senses and those under which their deliverances are particularly liable to be deceptive. We have whole catalogues of perceptual illusions of which we are aware, and we can and do correct for them. This itself seems to indicate some understanding of the mechanisms in play, even if it is imperfect. The upshot is that sensory perception is familiar enough to us that we have a kind of system (not perfect but a system nonetheless) by which to gauge its reliability in particular cases. It may be true that in no particular instance can we be absolutely certain that our senses are not deceiving us. But if we’ve agreed not to take the argument from illusion seriously, this is no problem.

However, if 3B gives an accurate picture of platonic perception, this does strike me as a serious problem. Norton’s argument view can say quite simply that thought experiments fail when the argument of which they are but a picturesque presentation is either unsound or invalid. We can choose between thought experiments with different conclusions by weighing the comparative strength of the arguments they can be reformulated as. This is all very neat and convenient. But if platonic thought experiments are not arguments, but perceptions of abstract entities, and this perception is fallible, how are we to choose between them when their ‘findings’ conflict? It seems to me that if the Platonist view is to be persuasive, we need to be able to say that the working of platonic perception is not just mysterious, but that it is governed by something like the sort of regularities governing ordinary sense perception. Further, we need to be able to say something about these regularities, so as to ascertain the conditions under which a platonic thought experiment is most likely to be a genuine source of a priori knowledge. I am not ready to concede that the Platonist cannot meet these demands, but doing so would seem to require a more robust account of platonic perception than what Brown gives us.