Wednesday, February 25, 2009

Williamson's Modal Epistemology

Williamson believes that our knowledge about what might have been and what must be derives from our knowledge about counterfactuals. His rough idea is as follows. There are interesting biconditionals schemas that relate metaphysical possibility and necessity to certain kinds of counterfactuals. We can formulate these biconditionals as follows (please excuse my crude notation system. I hope everyone will be able to figure out what these are supposed to say):

17. []A iff (~A[]--> (P&~P))
18. <>A iff ~(A []--> (P&~P))

Since these biconditional schemas are true, if we can come up with an account of how we come to know certain counterfactuals, then we might be able to extend that account to say how we come to know that certain claims are necessary and that certain claims are possible. This is Williamson's project.

Williamson has a lot to say about how we come to know ordinary counterfactuals. I'd like to grant to him that we come to know ordinary counterfactuals in the way he indicated. However, I think there are still problems with his account of how we come to know that a claim is necessary or that a claim is possible.

My first objection to Williamson's account involves noting that the counterfactual schemas above involve strange, non-ordinary counterfactuals. Although Williamson has given us an account of how we come to know ordinary counterfactuals, he has not said much about how we come to know these strange counterfactuals. I might be willing to grant that we can come to know some of these non-ordinary counterfactuals. For example, I can come to know that if there were a barber who shaved all and only those who don't shave themselves, then there would be a barber who both shaves himself and does not shave himself. I can come to know this simply by drawing out the logical consequences of the antecedent of that counterfactual. But, suppose it is impossible for two objects to be co-located. Now, I'd like to know how I might come to know that if two things were co-located, then pigs fly and it is not the case that pigs fly. The claim that two objects are co-located is not inconsistent. So, I cannot draw the contradiction as a logical consequence of the claim that two objects are co-located. But, presumably some metaphysicians know that it is impossible for two objects to be co-located (given our supposition). So, how do they come to know this fact? It doesn't seem to me that Williamson has said much about this.

My second objection to Williamson's account is that his account seems to require that we know (17) and (18) above. If we did not know (17) and (18) then we would not be justified in believing that possibly P is true even through we are justified in believing that it is not the case that if P were true then P and not P would be true.

My third objection is merely an extension of one of the objections that Williamson considers. Williamson responds to the objection that his acocunt requires that all counterfactuals with necessarily false antecedents are vacuously true. However, the objector claims, there are some counterfactuals with necessarily false antecendents that are true and others that are false. Williamson gives several good explanations of why we might be mistaken in thinking that these counterfactuals are sometimes true and sometimes false. I find his explanations very plausible. However, the theorist who thinks that some counterfactuals with necessarily false antecedents are true while others false has more to say than simply that he has an intuition regarding certain counterfactuals. Such a theorist can say both that he has an intuition and that he has a prior commitment to an ersatzist account of worlds that allows for impossible worlds which can be used in an account of counterfactuals that satisfies his intuition. So, it seems to me that Williamson needs to say more in response to such a theorist. Not only does Williamson need to explain away our intuitions about these counterfactuals, but he needs to say why it is better to explain away our intuitions rather than accept an account of counterfactuals that satisfies those intuitions.

Tuesday, February 24, 2009

An Argument against Presentism

Presentism is the thesis that no non-present objects. I was just thinking about this simple argument against presentism and I was wondering what all of you might think of it.

1. The proposition that 2+2=4 is not ever anywhere.
2. for anything whatsoever, if that thing is ever present, then it is somewhere at sometime.
3. So, the proposition that 2+2=4 is not ever present.

(1) seems intuitive. It does not seems as though we would be able to find a proposition if we just looked hard enough. Even if we could check every spatial region at every time, we would not be able to find the proposition that 2+2=4. but, if that proposition did at some time exist at some region, then it seems like we would be able to find it if we just looked.

Premise (2) is true because of the manifold nature of space-time. Given that space is three dimensional, no object can be some distance from me along one dimension without also being some distance from me along the other two dimensions (perhaps that distance is a zero distance). This is because the regions of one dimension are just composed of the regions of another dimension. So too, since time is putatively just composed of blocks of space, anything that is ever present must also at some time be spatial. (3) seems to follow from (1) (though the validity of the inference might be in question, there is no question that the inverence is cogent)

4. If the proposition that 2+2=4 is not ever present, then it is not present.
5. So, the proposition that 2+2=4 is not present.

Premise (4) seems very plausible. If something is not ever present, then it simply is not present. If something is present, then it is present at some time (namely the present). (5) follows from (3) and (4).

6. If the proposition that 2+2=4 is not present, then presentism is false.
7. So, presentism is false.

(6) seems obviously true. If presentism is the thesis that everything is present, then if something is not present, then presentism is false. So, if the proposition that 2+2=4 is not present, then presentism is false. (7) follows validly from (5) and (6).

I see several responses that someone might make to this argument. Some of the responses would probably be more widely accepted than others. Someone might, for example, reject (6) on the grounds that propositions do not fall within the scope of the quantifier 'everything'. This view might be most acceptable to non-serious presentists. such presentists might already accept that Socrates stands in relations to me and even that 'Socrates' refers. However, they reject that Socrates refers to anything that falls within the scope of 'exists' or 'everything'. If we are willing to accept the non-serios presentists position, then it shouldn't be too difficult to accept that the proposition that 2+2=4 also stands in relations, that 'the proposition that 2+2=4' refers but that that referent fails to fall within the scope of 'exists' and 'everything'. Moreover, this view might actually be held by Graham Priest. I think this is my preferred response to the argument (though I do have worreis about how to analyze the definite description), but I think this response would not be widely accepted.

I think that some presentists would deny (1). They might say that I am confusing the relation of existing-at with the relation of being located-at. To exist at a region is merely to be in the domain of quanfification for a region. To be located at a region is to have some kind of presence at that region. For example, I am not located at my apartment right now. However, I am within the domain of quanfication for my apartment. Hence, I exist-at my apartment without being located there.

I think that this way of rejecting (1) is mistaken. I am not sure I completely understand 'exists-at' but insofar as I understand it, it seems obvious that it implies a presence of some kind. If I exist-at my apartment, then I better be in my apartment. My opponent might push further by saying that I am only introducing further confusions. I am confusing 'exists-in' and 'exists-at' or maybe I am confusing 'exists with respect to' with 'exists-at'. But, I think it is my opponent who is introducing confusions. In the argument above, I refrained from using any phrase like 'exists-at'. So, it is not enought to simply say that I am confusing 'exists-at' with some other relation. My opponenent needs to say something about how this relates to premise (1).

My guess is that someone who claims that I am confusing 'exists-at' with 'exists-in' or 'exists with respect to' has some kind of analysis of 'The F is not ever anywhere' in mind; she has an analysis that employs 'exists-at' or 'exists with respect to' or whatever. But, any analysis of 'The F is not ever anywhere' that implies that 'The proposition that 2+2=4 is not every anywhere' expresses a falsehood has a singnificant strike against it. Such an analysis better do a lot of good theoretical work to account for such a counterintuitive consequence. I don't know for sure, but my guess is that there are not such strong theoretical benefits to the proposed analyses.

So, if (1) and (6) are okay, then we are left with (2) and (4). I can't think of any theorist who denies (2) or (4) and I can't think of a plausible metaphysical view that implies the denial of (2) or (4). If any of you can, I'd like to hear about it. In any case, it seems to me that a view that denies (2) or (4) will have something interesting to say about the particular quantifiers 'ever', 'sometime' and 'somewhere'. I'd like to hear what such a view has to say.

Tuesday, February 17, 2009

Sketching the First Half

Having just completed the (epic) fourth chapter, it seems to me that the general agenda Williamson had for the first half of the book is now over and the fifth chapter will take us onto something new. With this in mind, perhaps it will be helpful (I'll find it helpful, at any rate) to look back on what Williamson was up to in the first half, now that I have the wisdom of hindsight.

Here's the short version as I see it, though I'm certainly open to being corrected.
Some people seem to think that what distinguishes philosophy from other disciplines is that philosophy is in some distinctive sense merely linguistic or conceptual (chapter 1). Two questions: what could they mean by this, and is it true? Here's one thing they could mean: all philosophical theses are about language or thought. But this is false (chapter 2). Here's another thing they could mean: all philosophical theses are analytic and so less substantial than the theses of other disciplines. But this is false if we understand analyticity in terms of a metaphysical criterion like "truth in virtue of meaning" (chapter 3). It's also false if we understand analyticity in terms of an epistemological criterion like "assent entailed or constituted by understanding" (chapter 4). So without any idea about what else people might mean by saying that philosophy is primarily linguistic or conceptual, we can tentatively conclude that it's not.
Does this seem like a fair characterization of the first half of the book? If so, why the heck was the first half so long? :)

My main complaint about the argument up to this point is the same one I've shared before: that it doesn't seem like he clearly identifies his opponent. Surely someone could admit that not all philosophical theses are about language (or thought) and also admit that not all philosophical theses are analytic in any sense and yet also maintain that at best philosophy can help us learn about ourselves and not the world around us. Perhaps this character would have to deny the sort of claim that Joshua has pushed in some of the previous comment threads -- namely, that one perfectly good way to learn about the world is by learning about ourselves. But it seems to me that THIS is where the dispute is located...not in the sort of pedantic maneuvers involved in trying to come up with an adequate conception of analyticity.

Epistemic Analyticity

I'm sorry this post is a bit late. This chapter was rather long and I only just finished reading it. It also turns out that, due to the length of the chapter, a significant amount of time has passed since I read the beginning sections. I mention this because I think that Williamson addressed the idea that I am going to bring up in this post. But, since he addressed it toward the beginning of the chapter and since he said a lot in this chapter, I don't remember exactly what he said in response to the idea I'm going to present.

In the last chapter, Williamson considered metaphysical accounts of analyticity. However, such accounts suffered from a gap problem; there always seemed to be a gap between the analytic status of a sentence and our putatively easy knowledge of the proposition expressed by that sentence. That is, it seemed that there was no way to support the idea that if a sentence is metaphysically analytic, then it expresses a proposition that is epistemically accessible independant of various experiences. In this chapter, Williamson considers epistemic accounts of analyticity. The hope is that epistemic accounts will not suffer from such a gap problem.

Williamson approaches the subject in a rather circuitous way. He first introduces understanding/assent links and then suggests that such links can be used to support the claim that analytic sentences express propositions that are (in some sense) easily known. I am not exactly sure why he didn't just get straight to the heart of the issue. Although he considered unserstanding/knowledge links and understanding/justification links, he did not make them the central issue of his discussion. In this post, I'd like to consider approaching the idea of epistemic analyticity more directly.

Let's start with the intuitive idea that any possible native English speaker who understands a sentence like "Every vixen is a vixen" should have some positive epistemic status toward the proposition expressed by that sentence unless s/he has strong evidence against that proposition. Alternatively, some one might say that any possible native English speaker who understands the sentence in question will be justified in believing the proposition expressed by that sentence as long as s/he has no defeaters. Or, perhaps someone might say that any possible native English speaker who understands the sentence will be prima facie justified in believing the proposition expressed by that sentence. I am not exactly sure how to spell out this intuitive idea and I am not sure if the three things I wrote above are even (in any sense) equivalent. but, I think the idea, vague though it is, is clear enough to think about. So, let's just take the following principle and run with it under the assumption that prima facie justification can be overwhelmed by countervailing evidence:

(EA) For any English sentence S, S is epistemically analytic (if and) only if any possible native english speaker who understands S is prima facie justified in believing S.

The idea here seems to be that analytic sentences are such that understanding them is constitutive of some kind of evidence for the proposition expressed by that sentence. Of course, one can have evidence against the proposition expressed by an analytic sentence. So, for example, the theorists from Williamson' example have evidence against the proposition expressed by "every vixen is a vixen" because they believe or have evidence for some alternative theory that suggests that the claim that every vixen is a vixen is not true. Thus, Peter is not justified in believing that every vixen is a vixen becuase he has reason to believe that such a claim entails that vixens exist. This does not show, though, that he is not prima facie justified in believing that every vixen is a vixen. He might very well be prima facie justified yet have evidence that makes him ultimately not justified in believing that proposition. Similar things can be said for Stephan who denies "every vixen is a vixen" because he thinks that certain sentences with vague expressions are indeterminate in truth value.

Williamson does consider a couple of objections to something like (AE). If I remember correctly, he considers a case involving a man who decides to believe phlogiston theory simply because he likes the word or has good memories involving the word or something like that. Williamson claims that such a theorist is not even prima facie justified in phlogiston theory. I am a bit confused by this example though. Are we supposed to be taking certain tenets of phlogiston theory as analytic? why can't we, for example, simply say that our theorist is not at all justified in believing the central tenets of phlogiston theory and, moreover, those tenets are not analytic? I honestly don't remember what Williamson says in response to these questions. So, if someone can help me out, I would appreciate it.

However, I think there is a decent response to this criticism even if we accept that certain central tenets of phlogiston theory are analytic. We should make a distinction between being justified in believing and justifiably believing a proposition. Someone can be justified in believing a proposition, yet fail to justifiably believe that proposition. The theorist who believes phlogiston theory might be in such a position. Perhaps his mere understanding of certain sentences of phlogiston theory provides him with prima facie justification for the propositions expressed by those sentences. Moreover, absent any evidence against those propositions, he might even be justified in believing them. However, if he believes those propositions because of his fond memories, then he is not basing his belief appropriately. That is, he is not justifiably believing the propositions even though he is justified in believing them.

I kind of like (AE). I'm sure there will be problems with it. But, as far as I can see, Williamson has not introduced any such problems. One might worry that if there is such a link between understanding and prima facie justification, there needs to be an explanation of that link. In other words, we need a theory of why those sentences like "every vixen is a vixen" are such that mere understanding of them implies prima facie justification in the propositions they express. I am not sure how to respond to a demand for an explanation of such a link. However, I am inclined to say that nothing more needs to be said. Understanding such sentences is enough to provide prima facie justification for the propositions they express. Perhaps understanding them even constitutes prima facie justification. But, I am not sure about the plausibility of defense.

Wednesday, February 11, 2009

Pragmatics

We often say just a little and convey quite a bit. When there is a small kitchen fire, I might say "There is a fire extinguisher under the cupboard" and pragmatically convey that the nearest working fire extinguisher is under C (some particularly salient nearby cupboard). There is a question, though, that I want to ask about pragmatics. When we utter a sentence and pragmatically convey some bit of information, is it the sentence that we utter that triggers the pragmatic conveyance or the content of the sentence that triggers the pragmatic conveyance?

One initially plausible answer is that it is the content of the sentence that triggers the pragmatic conveyance. After all, if I say "there is a fire extinguisher under the cupboard" to someone who does not speak any English, then no information will be pragmatically conveyed to that person. but, if the sentence (and not the content) triggers the pragmatic conveyance, then it seems that information would be pragmatically conveyed to such a person.

Here is another reason to favor the view that pragmatic conveyance is triggered by the content of a sentence rather than a sentence itself. If someone says a a native Spanish speaker "hay un extintor de incendios en el marco del armario" then he will convey to that Spanish speaker the same thing that I convey when I say "There is a fire extinguisher under the cupboard". The best explanation of this is that the content of my sentence and the content of the Spanish sentence is the same and that content conveys that the nearest working fire extinguisher is under C (some particularly salient nearby cupboard).

Unfortunately, there are some troubling cases. First, there is a problem of particular conversational implicatures. Suppose that we have two people, one of whom is a believer is in a pagan religion that believes that Bolti is a vile god that throws thunderbolts from heaven on those whose corps fail. The other is a pagan who believes that Mani is a kind god who throws mana from heaven on those whose crops fail. Assuming that there are no such gods as Bolti and Mani and assuming a certain kind of Millianism, the content of "Mani is listening" is the same as the content of "Bolti is listening". Hence, if pragmatic conveyance is triggered by the contents of sentences rather than the sentences themselves, then someone who utters "Bolti is listening" will convey the same information as someone who utters "Mani is listening". But, this is just not correct. If our first pagan says to one of his friends "Bolti is listening" after the friend confesses that his crops might fail, it seems he has pragmatically conveyed that thunder bolts might fall on his friend. On the other hand, if the second pagan says "Mani is listening" to a friend who has just confessed that that his crops might fail, then it seems he has not pragmatically conveyed that thunder bolts might fall on his friend, but rather that mana might fall on his friend. Thus, it seems that it is not the content of those sentences that triggers the pragmatic conveyance.

Here is another example. Suppose I introduce the word "flugi" to mean the same thing as whatever adjective would be most offensive to Mr. Wake. I then say "Mr. Wake is a flugi" to Mr. Wake. I presume he will not be offended. But, that seems to indicate that whatever is offensive about a use of a particular word, it is not part of the content of that word, but rather part of whatever is pragmatically conveyed. But, now we have another reason for thinking that pragmatic conveyance is triggered by the words or sentences and not the contents of words or sentence. This is becuase if I say to Mr. Wake "You are a flugi", then (as I said before) he will not be offended. But if I say to Mr. Wake "you are an A" where 'A' is whatever word is the one that is most offensive to Mr. Wake, then I will offend him. Since "You are a flugi" and "you are an A" have the same content (in thier respective contexts), then it looks like the pragmatic conveyance is not triggered by the content.

I am not exactly sure what to take away from this discussion. I am inclined to say that pragmatics is much more complicated than one might expect. Pragmatic conveyances aren't just triggered by contents and they are not just triggered by sentences or words either. Rather pragmatic conveyances are triggered by words or sentences in combination with their meanings. On this view, it is not simply the word (taken as a sound of inscription) that triggers a pragmatic conveyance and it is not just the meaning of the word either. Rather, it is something like the word combined with the meaning.

Monday, February 09, 2009

The opposition?

Despite having gotten off to a good start, so far I'm not nearly as impressed with this book as I thought I would be. Part of the problem, I think, is that it's unclear to me exactly who Williamson means to be addressing. In my post on the last chapter, I complained that he was setting up a straw man because those in favor of the conceptual turn must have something more interesting in mind than merely the claim that all philosophical theses are *about* language/thought in Williamson's various senses of 'about'. When I started chapter 3, then, I was excited because it seemed like Williamson was going to address this very point. But I still think he must be misunderstanding or misrepresenting his opposition, whoever they are.

His main point in this chapter is to argue that thinking about analyticity as "true in virtue of meaning" doesn't entail that analytic truths are insubstantial. I take it that in the next chapter he'll argue that thinking about analyticity in terms of some epistemological formulation also doesn't entail that analytic truths are insubstantial, and hence we get a fuller defense of the claim that philosophy is more than merely conceptual. But I'm a bit skeptical of this strategy, in part because I would think we should *begin* with the presupposition that analytic truths are less substantial and then go on to investigate both what this means and also whether all philosophical truths count as analytic. Doesn't it just seem obvious that the truth expressed by "Vixens are female foxes" is somehow less substantial than that expressed by "There are black swans"? Maybe this means I'm just coming at it from a different perspective, but I wouldn't have thought that the burden was on those who made these claims of insubstantiality. Or, at least, the burden on them is not to show THAT these truths are insubstantial but instead to say in what their insubstantiality consists. That seems like an interesting project, but I don't really see Williamson engaging concretely with those who would wish to embark on it.

P.S. Sorry I don't really have anything terribly penetrating to say about the book so far...I'm still trying to get my head around the general project, and I haven't been very impressed so far with the clarity of his writing.

Sunday, February 08, 2009

Modal-Analytic Truths

I think I agree with much of what Williamson says in this chapter. It seems clear, for example, that no metaphysical conception of analyticity will vindicate the idea that analytic truths are insubstantial. There are, however, a couple of small points that Williamson makes that I disagree with.

Williamson claims that this sentence:

S1: It is raining iff it is actually raining.

expresses a modal-analytic truth. I disagree.

A modal-analytic sentence is a sentence the meaning of which is sufficient for truth. A meaning is sufficent for truth "just in case necessarily, in any context any sentence with that meaning is true." In what follows, I will assume that the meanings of sentences are propositions. Hence, it will be ligitimate to say that a proposition is sufficient for truth. With this definition in mind, we can easily show that S1 is not a modal-analytic truth.

To see that S1 does not express a modal-analytic truth, first consider the following sentence:

S2: It is raining iff it is raining in actuality.

If we take 'actuality' as an indexical that picks out the world of whatever context it is expressed in, then this sentence, just like S1, will express a true proposition in any context. Whatever proposition it expresses will be contingent. And, most importantly, whatever proposition it expresses will fail to be sufficient for truth. To see that this latter claim is true, let 'Alpha' name whatever world happens to be the actual world. Now, it is clear that the proposition expressed by S2 in a context that has alpha as its world will be the same as the proposition expressed by the following sentence:

S3: It is raining iff it is raining in Alpha.

Let's call the proposition expressed by S2 and S3 in such a context, say our context, 'P'. Since 'Alpha' is a name, rather than an indexical, then in any context, S3 will express P. Consider a context C that is such that alpha is not the world of C. Suppose that in the world of C it is not raining whereas in the alpha it is raining. Then, the proposition expressed by S3 in C will be false. That is, P will be false in C. But, that means that the sentence S3 will be false in C. So, possibly, in some context, a sentence that has P as its meaning is false. So, P is not sufficeint for truth. But, P was the meaning of S2 in our context. So, the meaning of S2 (in our context) is not suffient for truth. So, S2 is not modal-analytic

I say that the same kind of argument will show that the meaning of S1 is not sufficient for truth. That is, S1 is not modal-analytic. All we need is a non-indexical adverb that happens to have the same meaning as 'actually' in our context. Let's introduce the adverb 'alpha-ly' to be just such an adverb. Now, we can run an argument perfectly parallel to the one introduced above. The conclusion of that argument is that the meaning of S1 is not sufficient for truth and hence S1 is not modal analytic.

I think a general lesson can be learned from this exercise. Namely that sentence is modal-analytic only if its meaning is necessary. If the meaning of a sentence is contingent, then we can always come up with a way of expressing that meaning using non-indexical terms. Whatever sentence we come up with will express the contingent proposition in a context where that proposition is false. Hence, the proposition will not be suffient for truth. Hence, any sentence that expresses that proposition will fail to be modal-analytic. So, contrary to what Williamson says, the notion of modal-analyticity does not violate the Kripke contstraint on analytic truths. That is, if analytic truths are modal-analytic, then analytic truths are necessary, just as Kripke claims.

Thursday, February 05, 2009

Rights and Permissions

I have some ethical issues that I want to discuss. I know that it is not normal for me to discuss such issues, but I hope everyone will forgive me for this unusual diversion. I have been teaching ethics classes for a little while now and I've noticed that my students tend to use the word 'right' when philosophers would typically use the word 'permitted'. For example, my students might object to a view by saying 'no one has a right to do that' whereas a philosopher would put the objection by saying that 'no one is permitted to do that'. Similarly, my students often say 'we have a right to do A' in a situation where a philosopher might typically say 'we are permitted to do A'.

Many years ago, I took a class on moral rights theory and my students comments have made me start to think about the nature of moral rights again. In my rights class, we talked about two reductive theories of rights. The first reductive rights theory can be stated as follows:

(RR1) Necessarily: for any S and any action A, S has a moral right to do A iff S is morally permitted to do A and no one is morally permitted to stop S from doing A.

(Let's ignore complications that might arise with the generality of these claims and take all permissions, obligations and (hence) rights to be presumptive or prima facie.)

If (RR1) is correct, then it is logically consistent to say that someone is permitted to do A and yet doesn't have a right to do it. That is, to be a bit more precise, the conjunction of (RR1) with the thesis that someone is permitted to do some action yet does not have a right to do that action is logically consistent. So, from a logical point of view, it seems that we are saying something more when we say that a person has a right to do something than when we say that he is permitted to do so. but, my students don't seem to talk this way. They seem to take having a right to do something as equivalent to being permitted to do it.

I think that my students might be on to something. Although the position that someone is permitted to do something even though they don't have a right to do so is logically consistent, I am not sure that it is metaphysically possible. I can't seem to think of a situation where some one is morally permitted to do something yet some second person is morally permitted to stop that first person from doing that thing. That is, the following permission principle seems true to me:

(PP) Necessarily, for any S and any A, if S is morally permitted to do A, then no one is morally permitted to stop S from doing A.

Here is my quick defense of that thesis: Suppose that possibly, there is a person, S1, who is permitted to do A and yet there is a second person S2 who is morally permitted to stop S1 from doing A. If S2 is morally permitted to stop S1 from doing A, then there must be some negative moral feature of S1's action that warrents its being stopped. But, if there is some negative moral feature about S1's action that warrants its being stopped, then S1 is not really morally permitted to perform that action (contrary to our supposition). So, it seems to follow that necessarily, for any S and any A, if S is morally permitted to do A, then no one is morally permitted to stop S from doing A. That is, (PP) is true.

If (PP) is true, then although my students might be saying something with greater logical content when they say that someone has a right to do something as apposed to saying that he merely has a permission to do so, their claims might still be acceptable. After all, it is not really possible to have a permission without also having a right.

Of course, all this depends on my rather rough argument for (PP) and the controversial thesis (RR1). Some people, for example hold an alternative view about rights. They often say that a right implies more than just an obligation of non-interference. Some say that rights imply a kind of obligation of protection. It is hard to express this idea in a reductive principle, but the rough idea is something like the following:

(RR2) Necessarily: for any S and any A, S has a moral right to do A iff S is morally permitted to do A and everyone is morally obligated to ensure that no one interferes with S's doing A.

(RR1) is often called a negative rights theory whereas (RR2) is called a positive rights theory. Now, I have not thought about whether similar considerations would indicate a kind of metaphysical equivalence between having a right and having a permission given (RR2). So, someone might tentatively object to my claim that my students are on to something by endorsing (RR2). But, I think I might be inclined to turn such an objection on its head. That is, if (RR2) really does indicate that having a right is different from having a permission, then since my students are so inclined to take these two things as equivalent, we have some reason to favor (RR1) over (RR2). Of course, it is only a small reason and it might be defeated by other considerations in favor or (RR2). But, right now, I am inclined to reject this tentative objection.

So, that is my digression into moral philosophy for the day. I would be interested to hear what others think of my argument for (PP). I am also interested in thinking about whether a similar argument can show that the following permission/obligation principle is true:

(POP) Necessarily, for any S and any A, if S is morally permitted to do A, then everyone else is morally obligated to ensure that no one interferes with S's doing A.

If (POP) does happen to be true, then having a right and having a permission would be the same even if (RR2) is true. Unfortunately, this principle sounds less plausible to me, but I honestly haven't thought much about it.