Sometimes people say that for logical reasons there can be no examples of unknown or unknowable truths. The logical reason is this: to know that p is an unknown truth requires knowing that p is true, which contradicts the requirement of p being unknown.
Before I give examples of unknown and unknowable truths let me give examples of philosophers who died more than 100 years ago: Hume, Leibniz, Kant, and the philosopher first born in the 16th century. One might have thought that it is impossible for physical reasons to give such examples. After all, a philosopher who died more than 100 years ago just isn't there any more, so he can't be given as an example. But not so. In order to give an example of a dead philosopher it suffices to name or describe one; it is not necessary to dig him out.
With all these great comments coming in, I've decided to make them available in the RSS feed. (That also makes it easier to track reactions to a comment). While I was at it, I also built in an option to include only excerpts rather than the full postings. As a result, this blog now has the ridiculous number of six RSS feeds: One for my postings (that's the old feed), one for comments, one for postings and comments combined, and then all of them again but with excerpts only: postings, comments, combined. The feeds should now also support Conditional GET. Hope that works.
I guess I should to clarify my argument. The position I want to argue against consists of the following two claims:
1) "pain" denotes a physical entity, say CFF.
2) For no P that only contains physical terms is "P 
I am in pain" a priori.
"" is the material conditional. I've chosen the pain example only for brevity: if you think it matters, feel free to replace "pain" by something like "the phenomenal quality of my current red-experience".
Brandt Van der Gaast points out that Michael McDermott proposes something like the semantics I sketched on behalf of type-B materialism in his "The Narrow Semantics of Proper Names" (Mind 1988). That's true. But I think McDermott is almost silent on the matter crucial to type-B materialism, and there is no acceptable way to fill the silence without spoiling type-B materialism.
In The Conceivability of Naturalism, Crispin Wright notes:
When we disjoin or existentially generalise on names, the results -- for instance, "Tom or John was to blame", "Someone was to blame"-- had better not be conceived as forms of expression involving reference to disjunctive, or existentially general objects. There are no such objects.
What does he mean? Is his point merely the semantical hypothesis that "Tom or John" and "someone" should not be treated as refering expressions? It is probably easy to create a semantics where they are assigned a reference. I'm not even sure (though I believe it) that such a semantics would be perverse, given that lots of people have argued that expressions like "Tom and John" should be assigned some kind of reference to account for sentences like "Tom and John ate the cake". But at any rate, this presumably isn't Wright's point. For even if there was a disjunctive object consisting of Tom and John, it doesn't follow that "Tom or John" must be interpreted as refering to it. So the converse is also invalid: it doesn't follow from the fact that "Tom or John" doesn't refer that there are no disjunctive objects. The passage rather sounds like Wright has independent reason to believe in the non-existence of disjunctive and existentially general objects; a reason that merely gives further support to the semantic claim that "Tom or John" and "someone" don't refer.
First, on behalf of type-B materialism a reply to yesterday's
post. (Thanks to Sven Rosenkranz for pointing out something like this to me.)
What makes it the case that the red-quale is the referent of "the distinctive quality of my current red-experience"? Not causal or counterfactual relations. Not demonstrative baptising. Not other kinds of verbal and non-verbal behaviour. Right. But these attempts to naturalize semantic properties are doomed anyway. They presuppose that semantic properties are generally independent of how things appear to us, which they are not. In fact, how things appear to us is an essential component in many "modes of presentation" determining the reference of terms. E.g., the referent of "red" is what appears to us under normal conditions in the way red things appear to us. In a same manner, the referent of "the distinctive quality of my current red-experience" is what appears to me in this distinctive way. Which is the red-quale, which in turn is a property of brain states. But no amount of physical information will tell you how this property of brain states appears to me. Phenomenalism as a semantic doctrine may have been too extreme, but it was not entirely wrong.
Some strings of symbols and noises and brain states have semantic properties. What makes it the case that a
particular string or noise or state has the semantic properties that it has? One possible answer is that nothing
does: semantic properties are fundamental, primitive and inexplicable. That's incredible. Not only because
semantic properties just don't feel fundamental, as Fodor pointed out long ago. Much worse, it would
make little sense of our use of semantic vocabulary: we believe that our expression "the moon" denotes that
heavenly body up there; but how do we know? Maybe it really denotes the largest red thing in Alaska, or
Gottlob Frege, or nothing at all. If reference is fundamental,
facts about how "the moon" is used, how it got introduced, what conceptual role it plays, in what kinds of causal or
counterfactual relations it stands to other things, how people verify statements containing it, what degree of
naturalness various candidate referents have, etc. must all be considered irrelevant. On this view, there is a
possible world where all these facts about use etc. obtain, but where "the moon" denotes Gottlob Frege. Obviously that's silly.
Semantic properties are clearly determined by facts about use, baptising, causal chains, naturalness, etc. (In so far as they are determined at all, that is. No doubt sometimes the facts about use etc. are insufficient to settle whether a string or noise or state has semantic property A or B. But then it really is indeterminate which of the properties it has.)
The problem of intrinsic change is often put in misleading terms, like: "how is it possible for a thing to have incompatible intrinsic properties at different times?", or: "how can I be first bent and then straight?" Putting the problem this way invites wrong kinds of answers, like:
- There really is no problem here. Why should things not have incompatible properties, as long as they
have them at different times?
- Well, a thing can change its instrinsic properties by consisting of a substratum to which different properties attach at different times.
- How can I be first bent and then straight? Why, by standing up.
When I first read Lowe's proposed solution, I thought what he offers belongs to this class of answers that don't answer the real problem. In fact, his answer looks much like the third one above: How can I be first bent and then straight? By having parts, such as legs and a torso, which can change their spatial arrangement. Sure. But does that answer the problem?
When first introduced to the distinction between three- and fourdimensionalism and between perduranitsm and endurantism, many, myself included, have the feeling that both are valid ways of looking at the same reality and hence that at bottom they must be somehow equivalent or inter-translatable.
I still believe some of this. Consider for example the question of interpreting temporal predications. Endurantists say that "x is F at t" is true iff (the whole of) x stands in the F-relation to t, or iff x instantiates-at-t F, or something like that. As a perdurantist, I need not deny that. Rather, I have a further analysis of what it means to stand in the F-relation to t, or to instantiate-at-t F: it means to have a temporal part located at t which is F. Similarly, I needn't deny that I am wholly present right now. Applying the perdurantist analysis, what this claim says is that I -- the entire worm, with all his spatial and temporal parts -- have a temporal part which is present right now. Perhaps I could even try to make sense of claims like "people don't have temporal parts" by appealing to restricted quantification. But somewhere around this point the translatability comes to an end. Endurantists usually build the rejection of perdurantism into the very heart of their account, and it is certainly uncharitable to re-interpret this rejection so that it is after all compatible with what it rejects. (Here is something odd, by the way: how can it be uncharitable to interpret someone's utterances in such a way that they come out true rather than in a way in which they are false?)
There is a curious problem about rejecting both premise 2 and 3 in this familiar argument:
- It is conceivable that pain is not CFF.
- If it is conceivable that pain is not CFF then it is possible that pain is not CFF.
- If it is possible that pain is not CFF then pain is not CFF.
- Therefore: pain is not CFF.
I believe that premise 3 is almost certainly false: why can't 'pain' denote CFF at our world and D-fiber firing at other worlds? Or, even better, CFF in humans at our world and other states in other beings here and elsewhere? Some claim that 'pain' must rigidly denote a kind of diagonal state that all beings who are in pain share. But I've never seen a convincing argument why this should be so. Crispin Wright argues (in "The Conceivability of Naturalism") that a) the reference-fixing description for 'pain' is something like 'state of feeling painful', which is itself rigid, and b) necessarily, pain satisfies this description. But it is not at all obvious to me that the reference-fixing description for 'pain' is 'state of feeling painful', rather than, for example, the non-rigid 'state that feels painful' or something physicalistically more acceptable.