This paper presents a new challenge for libertarianism. The problem, in a nutshell, is that libertarianism appears to self-destruct in cases where conjoined twins—who share body parts—disagree over what to do with them. The problem is explored, and some solutions are proposed. The verdict is that accepting any of them will make libertarianism harder to defend.

When we seek a fuller understanding of individual liberty including its relational character, we confront a conundrum. The evident advantages of a single individual possessing liberty cannot be simply transferred to a greater number of beneficiaries. This conundrum is confronted with the resources of Hohfeld's analytical framework, developed specifically to elucidate the practical outworkings of interpersonal relations within the law. Attention is also paid to concerns expressed by von Wright over a representation of liberty (permission) within the resources of standard (...) deontic logic which fails to address its social aspect. The aggregate level of the Hohfeldian scheme is employed to represent a complete picture of liberty, but one that cannot guarantee benefits for a plurality of holders. The conclusion is reached that in order to extend the advantages of individual liberty to all, something other than liberty is required. (shrink)

Ben Bryan argues that the strongest challenge to natural rights theory is to explain how it overcomes the Problem of Authority. Given that our natural rights are multiply realisable by a range of equally reasonable social conventions, how or why ought one particular realisation have authority? I argue that Thomistic and Kantian solutions to this problem do not count as solutions from natural rights theory, and therefore offer my own solution. When theories of natural rights describe the rights we have (...) in terms that refer not only to moralised act-types, but rather, tell us which non-moralised act-types ought to be moralised in the relevant way, they avoid the Problem of Authority altogether. Such theories of natural rights are singularly realisable at the level of regulative conventional rules, and only multiply realisable at the level of constitutive conventional rules. The latter form of multiple realisability does not raise the Problem of Authority. (shrink)

Most philosophical accounts of human rights accept that all persons have human rights. Typically, ‘personhood’ is understood as unitary and binary. It is unitary because there is generally supposed to be a single threshold property required for personhood. It is binary because it is all-or-nothing: you are either a person or you are not. A difficulty with binary views is that there will typically be subjects, like children and those with dementia, who do not meet the threshold, and so who (...) are not persons with human rights, on these accounts. It is consequently unclear how we ought to treat these subjects. This is the problem of marginal cases. I argue that we cannot resolve the problem of marginal cases if we accept a unitary, binary view of personhood. Instead, I develop a new non-binary personhood account of human rights, and defend two main claims. First, there are many, scalar properties, the having of which are conducive to personhood. Second, different subjects have different human rights depending on which of these properties they have, and what threats apply to them. On my view, and contra most existing accounts, most marginal cases have some degree of personhood and are entitled to some human rights. (shrink)