Knowing permissibility

Some moral permissibility facts are logically trivial: it permissible to eat a morally appropriate breakfast. And maybe some moral permissibility facts permit something negative where the permissibility derives from the impermissibility of the opposed positive action: it is permissible to refrain from murder.

But a non-gerrymandered, logically non-trivial permission of a positive action is always something contingent fact (assuming it is a fact), and depends on empirical knowledge of the world or revelation. It is never a priori. The reason is simple. For any non-gerrymandered, logically non-trivially permission claim about a positive action A, we can find a logically possible situation in which A has some horrible consequences down the road, consequences so horrible as to make A impermissible (I am not here assuming consequentialism—even the anti-consequentialist has to allow that an action can become impermissible due to its having disproportionately bad non-intended consequences) such that we only know empirically or by revelation that these consequences do not obtain.

Therefore, while one can perhaps engage in purely armchair discernment of obligations, one cannot engage in purely armchair discernment of permissions (except in gerrymandered, logically trivial or negative cases). Data about the world around us is always needed, either obtained empirically or by revelation.

In particular, unless one's knowledge of a non-gerrymandered, non-trivial permission of a positive action comes from divine revelation, such knowledge suffers from the kind of defeasibility that all empirical knowledge suffers from. We're not going to be dealing in the self-evident when we make these permissibility claims.

This should lead to a certain epistemic modesty when making claims such as that eating meat or engaging in homosexual acts or lending at interest is permissible, unless one has apposite divine revelation (I think in the eating meat case, we do in fact have divine revelation that sometimes the eating of meat is permissible; but it does not follow that in our day, affluent Westerners who can get nutrition from other sources are permitted to eat meat).

Final version of Mark Murphy's letter to the APA

Mark Murphy has closed the comments period on his letter to the APA (which follows a petition and a counterpetition), and he is collecting signatures by email. The final version of his text, together with a link to email him a signature, is here.

I would like to quote from the final paragraph of his letter:

The APA is a diverse association marked by deep pluralism. Its members can rightly expect that the APA will respect the deep differences among them in judgments about how it is reasonable for individuals to live and for communities to organize themselves, and it is far from clear that the suggested change in course does respect those differences. It has been correctly claimed by some who argue for the change in policy that any such respect has its limits: the APA of course would not respect colleges the common life of which was built on racist norms. In our view the appeal to this argument highlights what is involved in excluding or marking as beyond the pale the job advertisements from these Christian colleges. There is no serious reasoned disagreement on racist norms; the APA can rightly feel free to speak on behalf of its members to condemn any such. What would be involved in changing the APA's policy with respect to these Christian colleges is that the APA would be taking an official stand, speaking on behalf of all of its members, on what are still matters of deep and reasoned controversy among them: whether so-called traditional marriage has any privileged normative status and whether sexual activity outside such marriage is morally suspect. For the APA to take such a stand would be a grave error and an injustice.

Deniers of qualia

Do deniers of qualia have qualia? Suppose I believe in qualia (I am not committed either way). If Martha is a denier of qualia, can I argue that Martha has qualia, just because I do? I can use an argument by analogy to argue that she has beliefs, thoughts, etc.: she behaves like I do who has beliefs, thoughts, etc., and has the same kind of brain structure as I do (the latter is kind of fishy, because we say this so confidently even without actually scanning Martha's head and my head). But what about qualia? I could say that she behaves like she has qualia. That's only going to be very plausible as an argument for qualia if qualia are causally efficacious, but I think that if there are qualia, they are causally efficacious. However, does she really behave like she has qualia? After all, unlike me (who, we are supposing, believes in qualia), when Martha has been aware of a red object, she denies that she has had a quale of red, and so on in other cases. Isn't that enough to sink the analogical argument?

Causally inefficacious qualia

The following question is probably very naive: If qualia are causally inefficacious, then how can I know that I experience any qualia, that I am not in fact a qualia-deprived semi-zombie who falsely believes himself to experience qualia? (I say "semi-zombie" because maybe one can be qualia-deprived and yet conscious in a qualia-free way. Maybe even folks who believe in qualia will say that when one is conscious of certain mathematical or moral or modal truths, there are no qualia.)

Mary's knowledge of red

Take Jackson's story: Mary is raised in a black and white setting, never experiencing red. She learns all there is to know about the physical constitution of the world. She leaves her black and white setting. She sees something red. She then comes to know something about the world which she didn't know before: she learns something about the experiences that other people have had. Hence the knowledge about the physical constitution of the world doesn't exhaust the possible knowledge about the world. Hence, the world is more than physical.

The standard objection to this is that this equivocates on "knowledge". Mary gains an ability, an ability to recognize and imagine red experience, say, after coming out of the black and white setting. Jackson has a rather nice answer to this, though. He supposes that Mary, after coming out of the room, toys with scepticism about other minds. But then she rejects the scepticism. In rejecting the scepticism, she does not gain any know-how. But she does gain the knowledge that others have that kind of experience, which she now has when she is looking at a tomato.

Here is a response to Jackson that has occurred to me. If Mary, before she saw red, really knew all there was about the physical world, she also knew that she will come out of her black and white setting, and that she will experience red. Before she has experience red, she can prospectively refer to that experience of red, the experience that she knows she will have (she can use "that" to ostend to that experience she will have). She also already knows that other people have had that experience. When she first sees red, she now "knows what that experience is like." But the only relevant fact in the vicinity, the fact that others have that experience, is a fact that she already knew. She now has a new way of pointing to "that experience" of hers: she can point to it introspectively, while before she could only point to it verbally ("dthat experience which I will have at t₇ upon looking at a tomato"). When she toys with scepticism about other minds, she temporarily loses the belief that others have that experience, and then she regains that belief when she rejects the scepticism. So Jackson is right in thinking that Mary loses something that isn't just know-how through scepticism and regain it. But perhaps he is wrong that what Mary loses through scepticism is what she learned about the experiences of others when she saw red. What she learned by seeing red stays there—it's just a new ability to refer to an experience of hers. What she loses is a belief that doesn't bother a physicalist.

I don't know whether the response stands up. I think it depends on the synonymy relations between indexical sentences. If I stand near near x and say "This is a tetrahedron" and you stand far from x and say "That is a tetrahedron", have we said the same thing? (Or, better yet, we both say "This is a tetrahedron", but your "This" gains reference through your pointing with your eyes, and my "This" gains reference through my pointing with my nose (with me closed-eyedly smelling the tetrahedron).) If so, then I think the response to Jackson goes through—we just have two different ways of fixing an indexical. If not, then it needs more work. But even so, if the difference between what Mary knew before she saw red and after she saw red is like the difference between a "this" belief and a "that" belief about something, it might not be a difference that should bother a physicalist.

Knowledge that and knowledge how

Here is an argument for the generally accepted thesis that knowledge-how is different from knowledge-that. Knowledge-that comes has two poorer cousins, true-belief-that and justified-true-belief-that. Knowledge-how does not seem to have such cousins.

In fact, knowledge-how seems more akin to true belief or justified true belief than to knowledge-that. Actually, it is possible to have knowledge-how in an area where one only has true beliefs. Suppose Georgina has all the skills and true beliefs that an automotive mechanic needs to have, but has very little in the way of knowledge. In fact, she has acquired her true beliefs about automotive repair from a fake psychic who, in a series of drug induced trances, uttered lots and lots of noises that happened to sound just like a series of lecture on automotive repair. Furthermore, Georgina has never actually touched a car. However, completely by chance, lightning has induced in her brain all the structures and motor memories that an experienced car mechanic would have. I am inclined to say that Georgina knows how to fix cars. The evidence of know-how is reliable execution, and she can do that. Suppose Georgina fixes your car. One can still question whether she knew how to do it. But if she reliably fixes cars, and does so consciously, with the right beliefs about how to do it, then she knows how to fix cars, no matter what source she got her know-how from.

The Phaedo equality argument

I've never quite got the Phaedo 75 "equality" argument. The point is made that whenever we have two equal things in the physical world, they are never simply equal, but are always only equal in some respect. From this we are supposed to infer that we do not get the concept of equality from the two things. Here are two readings that build arguments out of the text. Whether they're faithful to what Plato is saying is a different question.

Reading 1: Take two sticks. They are related in many respects. In one respect, they are equal. In another, they are not. Their may be equal length, but not in their width. Moreover, the length of the one is certainly not equal to the width of the other. (I include that remark in case one is tempted to say: "Why not just consider the same stick twice over, and then it'll surely be equal to itself?" But no, it, too, will only be equal to itself secundum quid—its length will be equal to its length, but not to its width, say.) The two sticks are related in all kinds of ways other than equality. Among these many relations that they stand in (such as inequality in width, difference in color, similarity in value, etc.), there is equality, in repect of length. To recognize the equality, in respect of length, among the many relations that they stand in, requires that we already have the concept of equality so that seeing it in the crowd of relations will pick it out from that crowd.

Objection: We can't do it just with two sticks, but if we have enough items, we can abstract equality from them. For it might be that a₁ and b₁ stand in a multitudinous set M₁ of relations including equality, and a₂ and b₂ stand in a multitudinous set M₂ of relations, and so on. But maybe the intersection of M₁,M₂,...,M_n contains only equality.

Response: There are so many relations that things stand in, that it is very unlikely that the intersection will be a mere singleton.

Objection: We can get to equality as long as we specify "in respect of length". So we do get the concept of equality from the sticks—"the relation in which their lengths stand to one another."

Response: First, the lengths of the sticks stand in infinitely many relations, equality being but one of those relations. (To give a non-Platonic example, the two lengths stand in the relation of being equal or the same color. Or the two lengths stand in the relation of being observed by the same observer.) So the problem reappears. Second, "length" must be defined in some respect—from which exact point on one end of the stick do we measure to which exact point on the other end do we measure? And, note, that almost surely we cannot really exactly specify points—the Cartesian coordinates are triples of real numbers, and almost no real numbers can be exactly specified (there are uncountably many real numbers, but only countably many can be exactly specified by us), so almost surely the ones here cannot be.

Reading 2: The two sticks are only equal in some respect R. But even the claim "the two sticks are equal in respect R" only holds in some further respect. And so on. Hence, we never get to equality itself. Concretely, let's start with: they are equal in respect of length. But that only holds in respect of one time—at some later time, one of the sticks will slightly oscillate and they won't be equal. So, they're equal in respect of length in respect of some time. But now, their length has one value in respect of one way of defining lengths, and another value in respect of another way of defining lengths. (There are probably little whiskers of wood fiber sticking out both ends. Do we measure them, or not? Which ones do we measure? Where in the atoms do we start measuring? And of course we have the uncertainty principles to contend with.) Moreover, in what way do we compare the lengths? Do we take a measuring stick to the one, and then to the other? But equality then only holds in respect of measuring sticks that don't change their lengths. And how do we define the measurement with the measuring sticks? Let's say they have tick marks. Where in the tick mark is the relevant point? It is not impossible that these questions go on ad infinitum. But even if they don't, they go further than we can answer them—and so we didn't get the concept of equality from the sticks.

Condoms

This post is based on a slight expansion of an analogy I once read in the New Oxford Review. Consider three cases:

1. Fred throws seed on a normal, fertile field. He enjoys the fresh air, the motion of the arm, the tossing of the seed, the symbolism of participating in God's creative activity.
2. Fred throws seed on an infertile field. He enjoys the fresh air, the motion of the arm, the tossing of the seed, the symbolism of participating in God's creative activity.
3. Fred covers up his field with a giant plastic sheet. (Why? Maybe because the seed has some kind of parasite that he doesn't want to reach the ground, or maybe because he doesn't want the bother of having any plants come up.) Then he walks on the sheet, and throws seed on it. He enjoys the fresh air, the motion of the arm, the tossing of the seed, the symbolism of participating in God's creative activity.

I think that in cases (1) and (2), Fred really is sowing the field. But not in case (3). Moreover, while one can symbolically participate in God's creative activity in sowing in an infertile field (think of how the Gospel also is sometimes appropriately preached to an audience who refuses to pay attention—the seed of the Gospel can fall on rocky ground), one does not do so by covering up the field with a giant plastic sheet and throwing seed on that (imagine covering up someone's ears, and then preaching the Gospel). The covering up of the field has an anti-creative symbolism. So the last bit of Fred's motivations in (3) in fact is mistaken.

In case (3), I think we would say that Fred is not sowing the field, though we might say that he is sowing the plastic. He is engaging in an activity different from that in (1) and (2). This is true whether we consider the symbolic theological meaning or not.

Suppose we do not see the difference between (3) and the first two cases. Then consider:

4. Fred puts a garbage bag in the middle of the field. He then tosses the seed, one by one, into the garbage bag. He enjoys the fresh air, the motion of the arm, the tossing of the seed, the symbolism of participating in God's creative activity.

But that's absurd. There is no symbolism of participating in God's creative activity—quite the opposite. And even if we do not consider the symbolism, it is clear that what Fred is doing in case (4) isn't sowing—it's throwing seed into a garbage bag. But (3) is not relevantly different from (4)—in (3), it's just as if the garbage bag were stretched flat over all of the field.

If this is right, then it is plausible that "sex with a condom" is not at all the same kind of activity as sexual intercourse. Just as in (3) and (4), the relevant kind of causal interaction between Fred and the soil was lacking, so in "sex with a condom" the relevant kind of causal interaction between the persons' reproductive systems is lacking.

This, of course, coheres well with the Catholic canonical view that intercourse with a condom fails to consummate a marriage. And if one adds the premise, accepted by the Christian tradition, that climactic sexual activity is only permissible in the context of intercourse, we get the conclusion that sex with a condom is not permissible, since it is a different kind of sexual activity (more like what the tradition calls "unnatural acts"). Moreover, this is true even in the case where the condom is used not for contraceptive purposes, but to prevent the transmission of disease (see my remarks in (3) on Fred's possible motivations).

Some remarks on Hume on miracles

1. Let's suppose for simplicity that miracles would violate of laws of nature. Consider then a "modernized" version of Hume's argument against miracles: The laws of nature have always been scientifically observed to hold. Whatever the merits of Hume's original argument, this version is really weak. It is, in fact, not uncommon for scientists to get data that does not fit what is predicted from the laws. When this data can be reproduced, it is taken seriously. But when the data cannot be reproduced, unless it is in some way spectacular, it will, I think, be dismissed as experimental error, an artifact of the particular experimental setup, etc. If only one scientist saw something on one occasion, and repeats do not show it, and no one else sees it, then it will not be taken seriously. The one scientist who saw the effect might investigate and try to find the source of the deviation, estimate to see whether the deviation falls within experimental error. But sooner or earlier, I think, the problem will be put aside, unless the data point was spectacular. However, miracles are not supposed to follow any rule—God is not a vending machine who produces a miracle when the right coins are put in. (God does answer prayers; however, he does not always answer them in the way expected; I think when we sincerely pray in Jesus' name, we will either get what we asked for, or we will get something as good or better.) So bringing science in does not help Hume's case.

2. Much of my knowledge of the sorts of regularities that miracles would go against is in fact through testimony. For instance, take the case that interests Hume most: the observation that dead people stay dead. I have never actually seen anyone die. I am sure Hume did. But unless one is a medical professional, a soldier or a witness to tragedy, one is unlikely to have seen very many people die. Moreover, one typically personally only observes a particular dead body for a fairly short time. Observe that once a body is buried, one no longer has direct observational data for the claim that the person stays dead. It could be, for all that one has directly observed, that the person came back to life, clawed at the coffin, and then asphyxiated again. Thus, one has very little direct observational data for the claim that dead people stay dead. But the bulk of our data for the claim that dead people stay dead comes from putting together the testimony of others.

Granted, we may have some indirect observational data. I have never seen graves opening when I visited a graveyard, nor have I driven by a funeral parlor and seen staff running out and screaming, with a formerly dead person walking out after them. However, in the case of most graves in a graveyard, it is through testimony that we know that there is someone in fact buried there. The indirect observational data depends on testimony, too, then.

Our knowledge of the regularity that dead people tend to stay dead depends largely on testimony. However, we only get the universal claim which Hume needs, the claim that all dead people always stay dead, when we dismiss some of the testimony available to us, namely the testimony for cases of resurrection. But it is no surprise that if we dismiss the testimony to the deviations from a regularity, what remains is testimony to the universality of the regularity.

3. In fact, miracle reports are very common, across many cultures. This should undercut one's confidence in any kind of Humean argument that miracles are apparent violations of universally holding regularities. For the sheer volume of miracle reports is strong evidence against the claim that the regularities always hold.

4. Hume himself thought that the ubiquity of miracle reports was evidence against their truth, because he thought that miracles should be confined to the true religion, and at most one of the religions could be true. However, I think we can now have a more ecumenical view of miracles. Moreover, I think we can distinguish between miracles that bear witness to a particular proposition and miracles that do not. A healing can simply be an act of divine love for the person healed and her friends/family, and there is no reason to deny that such miracles might hold quite universally.

But some miracles very clearly bear witness to a particular proposition. Thus, in the fifth century, apparently about sixty Catholics had their right hands and tongues cut out at the roots by an Arian heretic for espousing the doctrine of Nicaea. But these Catholics continued to speak, and presumably to preach the Nicaean doctrine. This seems to be a miracle that is a witness to a particular doctrine. Bishop Victor, writing two years after the alleged event, says:

If however any one will be incredulous, let him now go to Constantinople, and there he will find one of them, a sub-deacon, by name Reparatus, speaking like an educated man without any impediment. On which account he is regarded with exceeding veneration in the court of the Emperor Zeno, and especially by the Empress.

In the case of miracles that bear witness to a particular doctrine, when the doctrines conflict, one has a harder time making the ecumenical move. However, I do not know that there really are that many cases of reliable miracle reports that bear witness to incompatible doctrines. The case of the tongueless sub-deacon is very remarkable, and I do not know of any similar miracles reported on the part of the Arians. It is an interesting bit of religious history that at the time of the Protestant Reformation, one of the arguments adduced by the Catholic side was that claims as sweeping as those of the Reformers should be backed up by miracles—but none, the Catholic apologists alleged, were offered.

So Hume cannot dismiss ubiquitous miracle reports that are not tied to a particular doctrine. He could say something about mutual cancelation in the case of miracles that bear witness to a particular doctrine, but it is not clear that there is actually all that much in the way of reports of such miracles, of equal reliability, bearing witness to incompatible doctrines. And even if there were, it seems to me that the hypothesis that both reports are unreliable is less probable on its face than the hypothesis that only one of the reports is unreliable.

Teaching logic

While teaching logic for the first time (I am teaching to graduate students, but I haven't taught any logic before), I've finally realized how much I like constructive proofs. I gave a completely constructive proof of weak propositional completeness, by giving a simple proof algorithm that underlies this perl prover program. Basically, you start by proving excluded middle for each atomic. Then you just do proof by cases on all possible combinations of truth values of atomics. This only works for a finite number of atomics, so it only gives weak completeness. But the proof method is entirely constructive, simple enough that one can use it oneself (e.g., I used it myself when proving one of the De Morgan directions in class). I am not claiming it's at all new—it's not—but I had fun rediscovering it.

Then, today or Thursday (depending on whether time allows), I'll give a semantic proof of propositional compactness in the case of countably many atomics. (I am sure this proof has a name attached to it, but it's easier to make up than to look up.) Again, it's going to be entirely constructive, and pretty simple. It just uses induction and the lemma that if A is f-satisfiable (i.e., every finite subset of A is satisfiable), and Q is an atomic, then either A plus Q is f-satisfiable, or A plus not-Q is f-satisfiable. As it stands, this only works for countably many atomics, but in fact it also works for any case where there is a well-ordering on the atomics (and hence by the Axiom of Choice, it extends to the general case; but it is kind of nice to note that once one fixes the well-ordering on the atomics, it's entirely constructive). I'm not a logician. None of this is at all new. But I'm having lots of fun, hopefully of an innocent variety.

But I have also made an interesting sociological discovery: Students find set theory harder than first order logic. They seem to think of set theory as more abstract and strange. This was really weird to me at first, but that's just because I've been using sets for the larger part of my life, and only got to rigorous first order logic recently. Next time I teach the material, I will have to move more slowly through the beginning of set theory to make it clear that "member of" is not transitive but "subset of" is, that {{1,2,3}} has only one member, and so on. (Why, oh why, don't they teach computer programming starting with Grade 2 in all schools, so one could suppose familiarity with various kinds of abstract data structures by the time of college, which would allow for a nice stock of common concepts? It's a more useful intellectual and practical skill than, say, cursive handwriting.)

Inspiration and inerrance

Some people prefer to talk of divine inspiration of Scripture instead of Scriptural inerrance, because they think this way they can avoid affirming inerrance and hence being subject to the apparent counterexamples to inerrance. However, I think the right concept of divine inspiration will make God a full author of the text (so is the human author, of course; I am not here addressing the interaction of the two authorships). Sometimes it happens to an author that the text asserts something that the author did not assert. I doubt this can happen in the case of an omniscient and omnipotent author. If it cannot, then anything that the text asserts is asserted by God. Moreover, it seems central to Christianity and Judaism that God does not lie. Hence, the text only asserts propositions that God believes to be true. But the only propositions that God believes to be true are propositions that in fact are true. Hence, anything the Biblical text asserts is true. If we add some plausible counterfactual robustness to this story (a hard question exactly how to do this—cf. this post), we get inerrance. So inspiration, understood the way I want to understand it, entails inerrance.

I don't mean for the above argument that inspiration entails inerrance (which is basically an expansion of the enthymematic argument for inerrance in Vatican II's Dei Verbum, section 11) to convince those who don't believe inerrance. Rather, I am here interested in a different point. Even if we believe in inerrance, as indeed the Christian Tradition does, nonetheless we have at least two good reasons to focus on inspiration as the basic concept.

First, if we can argue from inspiration to inerrance, but not from inerrance to inspiration, then inspiration is likely to be the more basic concept. If something like the strategy in the first paragraph of this post goes through, we can argue from inspiration to inerrance. But we cannot argue in the opposite direction. Inerrance is a negative doctrine, namely that a text does not contain any false assertions, plus a bit of counterfactual robustness. Such a doctrine could be made true by all kinds of positive realities, of which inspiration is only one. For instance, an uninspired text would be inerrant if, say, God resolves to paralyze the person at the first sign of writing a false. For a more extreme case, God could make a text be inerrant simply by resolving to preventing the human author of the text from setting down any assertions (thus, the text might contain questions, commands, nonsensical rhymes, etc.)

Second, inspiration is a doctrine about all of Scripture. Inerrance is only a doctrine about the truth of assertions in Scripture. An assertion can be true, and intentionally both deeply misleading and spiritually harmful. And there are important portions of Scripture, of varying length, where the main business is is not the making of assertions—but the offering of prayers (especially in the Psalms), the making of commands, the giving of advice ("Go to the ant, O sluggard, and consider her ways, and learn wisdom" is not an assertion), and so on. Inerrance says nothing about those portions. Inspiration does.

Presumably, there is some analogue to inerrance in the case of those portions of Scripture (perhaps, the analogue to inerrance in the giving of proverbial advice is that the advice is helpful when appropriately applied by a phronimos). But these are analogues to inerrance, not inerrance itself, and it is to the doctrine of inspiration that we turn to find out what these analogues would be.

Computers and questions

Consider the following BASIC computer program:

input a
input b
print a+b

I run the program, and it pauses for input. I press "5" and "enter". Then it pauses for input again. I press "7" and "enter". It then displays "12".

Intuitively, the computer has answered the question: "What is 5+7?" But that's projection. From the marks on the screen and one's memory of the input, one can deduce that 5+7=12. But the computer program can be interpreted in a variety of ways. We could, for instance, take the program to answer a different question, the question of what an inscription of the decimal number equal to 5+7 looks like. In this case, the program's answer shouldn't be interpreted as a number, but as a numeral. Or we could take the program to answer the question of what the result of converting 5 and 7 (or maybe the ASCII codes 53 and 55) to binary, then adding the results together, and then converting back to decimal would be. And so on. There is an infinity of questions we could take this program to be answering.

All of these questions are different, and which one we take the computer to be answering is completely up to us. For, in fact, it is not the case that the computer is answering a question. Rather, we are using the computer to find an answer to some question or other, and there is an infinite number of questions we could be using the program to find an answer to. (We could be using the program to find an answer to the question whether the "enter" key works or not!)

It seems very implausible to suppose that there is any way of adding complexity to this program in such a way that it will become determinate which question the program is answering. Therefore computers simply cannot answer determinate questions.

Deep Thoughts XX

There is something to be said for an irrefutable theory: It can't be refuted.

[This isn't quite a tautology, because "There is something to be said for" has a valuative component that does not tautologously follow from irrefutability. Anyway, I am always amused when I see the move made against Intelligent Design in public debate: "It's irrefutable. And besides, the evidence is against it." It seems to be like the case of the man who complained that the food was revolting and the portions too small. (I am assuming that "refutable" means something weaker than "can be apodeictically disproved", since coherent scientific theories tend not to meet that standard of refutability.)]

Identity theory of mind

Here is a quick, and no doubt well-known, argument that mental states are not token-token identical with brain states. The argument makes assumptions I reject, but they are assumptions that, I think, will be plausible to a materialist. The idea is this. It is possible to transfer my mind into a computer, while preserving at least some of my memories, and with my brain being totally destroyed in the process (I reject this myself, but I think the materialist should accept Strong AI, and her best bet for a theory of personal identity is some version of the memory theory, which should allow this). Were such a transfer to be made, then I would have some of the numerically same token mental states (e.g., a memory of a particular embarassing episode) as I do now. But if these mental state tokens are now identical with brain state tokens, then it follows that it is possible that some of my brain states can survive the destruction of my brain, without any miracle, just by means of technological manipulation. But no brain state token of the sort that is correlated with memories[note 1], can survive the destruction of the brain, perhaps barring a miracle.[note 2] Hence, the mental states are not identical with brain states.

Of course, one might try a four-dimensionalist solution, supposing some temporally extended entity that coincides with the brain state prior to the destruction of the brain and with the electronic state after the destruction of the brain. But that won't save identity theory—it will only yield the claim that the mental state is spatiotemporally coincident with a brain state, or constituted by the brain state, vel caetera.

Maybe, though, what the identity theorist needs to do is to disambiguate the notion of a "brain state". In one sense, a brain state is the state of the brain's being a certain way. Call that an "intrinsic brain state" (note: it may be somewhat relational—I am not worried about that issue). If identity theory is understood in this way, the above argument against the identity theory works (assuming materialism, etc.) But a different sense of "brain state" is: a state of the world which, right now, as a matter of fact obtains in virtue of how a brain is.

Thus, consider the following state S: Alex's brain being gray, or there being a war in France. State S now obtains in virtue of how my brain is. But state S obtained in 1940 in the absence of my brain, since I did not exist then; instead, it obtained in virtue of there being a war in France. The state S is now a brain state, though earlier it wasn't. Call such a thing a "jumpy brain state": it can jump in and out of heads.

The identity theorist who accepts the possibility of mind transfer had better not claim that mental state tokens are identical with intrinsic brain state tokens but rather must hold that they are identical with jumpy brain state tokens. Put that way, the identity theory is much tamer than one might have thought. In fact, it is not clear that it says anything beyond the claim that the present truthmakers for mental state attributions are brain states.

Also, consider this. Presumably, for any jumpy brain state S, there is an intrinsic brain state S*, which right now coincides with S, and which is such that S obtains in virtue of S*. Thus, corresponding to the jumpy state Alex's brain being gray, or there being a war in France, there is the intrinsic brain state Alex's brain being gray. There is now a sense in which our identity theory is not faithful to its founding intuition that mental states are the states that neuroscience studies. For neuroscience certainly does not study jumpy brain states (neuroscience as such is not about wars in France, or information on hard drives). Rather, neuroscience studies intrinsic brain states. The identity theorist's mental state is identical with some jumpy brain state S, but it is S* that neuroscience studies.

And so there is a sense in which the identity theory is a cheat, unless it is supplemented with a non-psychological theory of personal identity that bans mind transfer between brains and computers. But the latter supplementation will, I think, also ban AI, since if computers can be intelligent, minds can be transfered between computers (think of a networked computation—the data can move around the network freely), and it would be weird if they could be transfered between computers but not from a brain to an appropriately programmed computer. Moreover, once one bans AI, one has made a claim that intelligence requires a particular kind of physical substrate. And then it becomes difficult to justify the intuition that aliens with completely different biochemical constitution (even an electronic one—cf. the aliens in Retief's War) could have minds.

Deep Thoughts XIX

No matter how much we strain our eyes, we will not see the invisible.