Wolfgang Schwarz

Lewis on multiply realizable properties

One of the many drawbacks of studying philosophy in Germany is that nobody kicks you when you spend years on your M.A. thesis. So hereby I publicly kick myself. As a consequence, this blog might become even more occupied with David Lewis than it already is.

To start this trend, here is a question about Lewis' functionalism. When a property P is multiply realizable, we cannot identify it with its realizers because then we would identify the realizers with each other, too. All we can do is locally identify P-in-k with its realizer in k, where k is a world or species or individual. Now what is P itself? In Lewis' papers on mind, he usually says that 'P' is systematically ambiguous or indeterminate, denoting the contextually salient realizer. (At least this is what I take him to say. He is not particularly explicit here.) The alternative would be to identify P with the diagonal property of being a P-realizer. The main reason why Lewis rejects this option (e.g. in 'Reduction of Mind') is that it is difficult to see how this diagonal property can occupy the causal role associated with 'P'. Difficult, but not impossible: In 'Finkish Dispositions' he proposes a solution, and consequently prefers identifying fragility not with the contextually salient realizer but rather with the diagonal property. Since then he apparently hasn't written anything more on the issue, so I would like to know if he has changed his mind on mental states (and heat, etc.) as well. (There may still be problems if the theoretical role is not entirely causal, so that even if the diagonal property can do the causal work, it might not be able to do the rest.) Or has he completely endorsed the third alternative – to simply leave the question unanswered: 'The folk well might have left this subtle ambiguity unresolved' ('Void and Object'). Can anyone help?

Carnap on rigid designators

In part II of Meaning and Necessity Carnap defines 'L-determinate designators' for rather specific languages (coordinate languages). I think that a more general definition is possible that pretty much meets Carnaps ideas. This more general definition simply identifies L-determinacy with what we nowadays call rigidity.

Infinite probability spaces

Does anyone know a good resource on probability theory with infinite probabilty spaces (if there is such a thing)? For example, I would like to know if the probability that an arbitrary real number lies between 0 and 1 is defined, and if so, how the obvious awkwardness of any answer can be explained away.

Email Virus

If you recently received an email from somebody called 'Wolfgang Schwarz' mentioning wolfgang@umsu.de and containing a strange attachment, please don't open it. It is the worm W32.Bugbear@mm. If you have opened the attachment, this page tells you how to remove it. Also please don't reply to the sender who is not me and completely innocent, since the mess really spread from my old windows machine. I'm very sorry about this.

Apriority vs. Analyticity

It is often said, correctly I think, that there are contingent but a priori sentences, e.g. "water is the dominant liquid on earth". Are these sentences analytic or synthetic? That is, what puts you in a position to know these sentences? Does understanding suffice, or do you have to invoke some other a priori means, like Gödelian insight? To me this seems wildly and unnecessarily mysterious. Of course understanding suffices, at least in ordinary cases. So there are contingent but analytic sentences. I wonder why this is hardly ever said. Does anyone really believe that those statements are synthetic a priori?

Sharing narrow content

Since narrow content is not determined by external factors, it depends much more on other propositional states than wide content. For example, if you believe that Aristotle was human whereas I believe he was a poached egg, the narrow content of all our beliefs about Aristotle will differ. When I believe that Aristotle was Alexander's teacher, you can't have a belief with exactly the same narrow content unless you also come to believe that Aristotle was a poached egg. Likewise for imaginings: When we both imagine Aristotle teaching Alexander, our imaginings cannot have the same narrow content.

Similarly, I think, if Ted believes that for any atoms there is a fusion, whereas Cian disbelieves this, they cannot share any imagining about atoms.

Restricted deducibility and deferential understanding

Dave Chalmers kindly explained his views on deducibility to me. He thinks that anything one could reasonably call non-deferential understanding of the fundamental truths would suffice for being able in principle to deduce macrophysical facts, provided that these fundamental truths, unlike my P, contain phenomenal facts and laws of nature. He also notes that I shouldn't have called these restrictions (to non-deferential understanding and the rich content of fundamental truths) assumptions, since they are really just restrictions. I'm still not sure if any kind of non-deferential understanding would suffice, but with the restrictions in place it's not as easy to come up with counterexamples as I thought.

A priority, deducibility and understanding

Back to the question of deducibility.

According to the deducibility thesis, the fundamental truths (plus indexicals, plus a 'that's all' statement) a priori entail every truth. More precisely, when P is a complete description of the fundamental truths and M any other truth, then, according to the deducibility thesis, the material conditional 'P M' is a priori.

Infinit analyses?

Dave Chalmers agrees that any concept can be explicitly analyzed by an infinite conjunction of application-conditionals. But he wants to restrict 'explicit analysis' to finite analyses. That certainly makes sense, but I doubt that there are any concepts for which the application-conditionals cannot be determined by finite means. For example, I think it will usually suffice to partition the epistemic possibilities into, say, 50 zillion cases and specify the extension in each of these cases. Admittedly, I can't prove that, but the fact that concepts can be learned and our cognitive capacities are limited seem suggestive.

On the very idea of non-explicit analysis

Dave Chalmers told me to read some of his papers. I have, and I'll probably say more on the deducibility problem soon. Here is just a little thought on conceptual analysis.

Chalmers suggests that we don't need explicit necessary and sufficient conditions to analyse a concept. Rather, we can analyze it just by considering its extension in hypothetical scenarios. What is it to consider a hypothetical scenario? The result seems to depends on how the scenario is presented. For example, 'the actual scenario' denotes the same scenario as 'the closest scenario to the actual one in which water is H2O'. But the difference in description could make a difference for judgements about extensions. Chalmers avoids such problems by explaining (§3.2, §3.5) that to consider a scenario is to pretend that a certain canonical description is true. Hence to analyze a concept, we evaluate material conditionals of the form 'if D then the extension of C is E', where D is a canonical description. (Are there only denumerably many epistemic possibilities or can D be infinite?) Now fix on a particular concept C and let K be the (possibly infinite) conjunction of all those 'application conditionals' (§3) that get evaluated as true. Replace every occurrence of 'C' in K by a variable x. Then 'something x is C iff K' is an explicit analysis giving necessary and sufficient conditions for being C.

There may not always be a simple, obvious, or finite explicit analysis, but at least there always is some explicit analysis. If moreover satisficing is allowed, it is very likely that we can settle with something much less than infinite.