I want to try to develop an argument against deontological libertarian moral principles that treat a wide range of our basic rights as flowing from morally powerful rights of self-ownership. I am curious how widely this problem afflicts a broader range of deontological views but I will not much pursue that here.
Previously (and following Nozick and Railton) I offered the criticism that such libertarian views have great trouble handing risk. The fear was that such views cannot explain why it is permissible for me to throw a stick for my dog when there is some small chance that the stick would violate the property rights of others. I now think (non-absolutist) libertarians should accept that, whatever amount of social good it takes to justify a property rights violation, they should say that it takes only 10 percent of that amount of good to justify a 10 percent chance of a rights violation. While this perhaps makes our rights more fungible for social good than the libertarian is comfortable with, it seems necessary to explain why we are permitted to fly planes, throw sticks, etc.
Now I am thinking the real problem (which again Nozick and Railton’s examples help us see) is that such libertarian views cannot adequately distinguish the moral seriousness of the wide variety of kinds of actions that violate our property-rights. Intuitively, strapping me down against my will and taking my kidney is a morally very serious offense but stepping on the edges of my property as a short cut against my will a less serious offense. Nozick offers us a one-size fits all amount of social good needed to justify a rights violation, namely, a catastrophic moral horror. But it is plainly implausible that it should take the same amount of social good to justify each of these two property rights violations. Our libertarian needs some way of marking the divide between more and less serious violations, and not just for the intuitive reasons offered above.
Imagine there is a pollutant that is produced by a wide range of human activity such as driving a car, flying a plane, running the lawnmower, making toasters, etc. Suppose this pollutant was such that the more of it one breathes, the itchier one gets once a year and this is the only effect of the pollutant. Even at maximal itchiness, however, the itchiness is not debilitating but rather only annoying. Presumably putting this pollutant into the air such that it is very likely I will breath it and be affected by it is a violation of my right to my lungs. You cannot cause stuff to end up in my lungs without my permission without violating my right to my lungs. My right to my lungs includes a right to determine what I will and will not put in my lungs.
Now if this rights violation were treated as just as morally important as taking someone’s organs against her will, then, since there will be many such rights violations as a result of the pollution, surely such pollution would be impermissible. But this would shut down much of the economy of the world we are imagining and it would radically restrict the liberties of people in such a world. Nozick, recoiling from such a picture, said that this “would ill fit a picture of a free society as one embodying a presumption in favor of liberty.” 
But this reveals a tension in the libertarian picture. On the one hand, liberty is just defined negatively, as the freedoms one is entitled to so long as you do not violate another person’s rights. So understood, there would be no infringement on liberty here. But Nozick’s reaction reveals that there is another image of liberty, one that includes us having a wide range of attractive options and the ability to move about freely. Usually the libertarian assumes that these two pictures will go together—that is, that respecting other people’s property rights will leave us tons of free space to enjoy (the permissibility of) a range of attractive options. But given the wide array of actions that in minor ways infringe on other people’s property rights, such as polluting, this view seems threatened.
I conclude that to avoid shutting down the world economy in nearby possible worlds and perhaps in this one, libertarians must mark a distinction between more and less morally significant property rights violations (I would have thought this should have been obvious even without the above argument). How might they do this?
There are several possible ways. One might look to how much a person values a certain property right and say that less valued property rights are morally less important. One might say that some property rights protect things that are objectively more valuable, regardless what the owner of the right thinks about the matter, and so protecting such rights are more important. And no doubt there are other options as well.
The key thought I want to urge now is that any plausible way of doing this will severely threaten the confidence it is reasonable to have that progressive taxation of the rich to provide for the infirm is wrong.
So, in a nutshell, failing to distinguish the moral seriousness of different property rights violations is intuitively repugnant and it yields crazy results that threaten our economy and the freedoms we currently enjoy (as is shown in the pollution case). But when we do distinguish between the moral seriousness of different types of property rights violations, we are left without a principled rationale for rejecting redistributive taxation, since it is very plausible that such violations will in most cases be among the not so serious instances of rights violations (like exposing others to pollution). And if the social good that accompanies such pollution is sufficient to justify a fair amount of pollution (even if not as nearly as much as we currently put out) despite it violating the rights of just about all humans, then surely the social good involved in progressive taxation may well be permissible as well so long as it produces great social good (and violates the property rights of far fewer people than pollution).
As I mentioned initially, it seems to me that a variety of deontological views are put under pressure by such worries. Surely there can be more and less morally important ways in which someone could violate the categorical imperative or use someone as a mere means. It seems plainly implausible that each such case should be treated the same by a moral theory. But then we are owed a story about how to distinguish the more important from the less important violations if such accounts are to be plausible.
But for now I hope to keep the focus on the problems that libertarians have in dealing with the range of moral seriousness of property rights violations, yet keeping cherished conclusions about the injustice of redistributive taxation.