It has been argued that “rights,” particularly the right to self-ownership (that is, property in one’s self) and its extension to those goods and services that are acquired, either through labor transforming land from the state of nature to capital or consumer goods, or through voluntary gift or exchange, cannot properly be applied to any other species than that of man. 

As Rothbard states in Ethics of Liberty:  “In short, man has rights because they are natural rights. They are grounded in the nature of man: the individual man's capacity for conscious choice, the necessity for him to use his mind and energy to adopt goals and values, to find out about the world, to pursue his ends in order to survive and prosper, his capacity and need to communicate and interact with other human beings and to participate in the division of labor. In short, man is a rational and social animal. No other animals or beings possess this ability to reason, to make conscious choices, to transform their environment in order to prosper, or to collaborate consciously in society and the division of labor. Thus, while natural rights, as we have been emphasizing, are absolute, there is one sense in which they are relative: they are relative to the species man.”      

This sentiment echoes that of Aquinas and Aristotle of man as separated from beasts, distinguished above all others by his capacity to reason. But how can a consistent thinker decry “universal principles” and “natural rights,” and discuss Crusoe in the “state of nature,” yet then draw such a narcissistic and arbitrary distinction? How can we, with any certainty, make the claim that a wolf has no capacity for conscious choice, or that a rabbit does not use its mind to pursue its ends in order to survive and prosper, or that an ant does not communicate with others to participate in the division of labor?     

Nevertheless, we must admit that the extension of natural rights to species other than man is fraught with difficulties, not the least of which is that so doing leads us immediately to question: to which animals must such rights be extended, if any, and why; and if extended to all, even bacteria or the minutest of single-celled organisms, must this not necessarily lead to the extinction of the human race entirely?    

Let us step back from the slippery slope of utter annihilation of humanity, pause a moment, and put our reason to use. First, it must be conceded that, if possession of reason is the primary criterion for distinguishing between those beings which can be said to have rights and those which cannot, rights are by no means a priori unique to men. To say otherwise is to make the unfounded assumption that man is the only being in the vastness of the Universe to have such a faculty, rather than to admit with proper humility that this is so only insofar as our limited knowledge allows (and even this admission is somewhat spurious as it hangs mightily on what we define reasoning to be).  Hence rights, and particularly the right to self-ownership, are not necessarily something peculiar to mankind, but must at least belong to any being demonstrating the capacity for reason. 

Furthermore, if reason is to be the litmus test for possession of the right to self, as we have stated above, we must give some precise definition of what we mean reasoning to be. For practical purposes, let us take reasoning to be the process of discovering ends, making subjective value judgements regarding those ends, devising means to the ends, and implementing those means. But what then of infants? Clearly, they do not demonstrate the capacity for reason (lest our definition be extended to howling for their mother’s teat). Does this mean they should have no natural rights, that they are similar in kind to a rock or tree or lion and no different?  Obviously not!     

It may then be argued that while infants do not currently possess the capacity for reason, they do so potentially, that they have rights insofar as they may become an adult human with the capacity to reason (which possibility no animal has). But then what of the severely disabled, mentally handicapped, or comatose who not only do not demonstrate reasoning but also never will? Do they have no right to self? Without question, not one among us, even the staunchest of critic, would be willing to concede such a thing. Being disabled, in that sense, makes them no less human, and hence no less possessed of the natural rights of any other human.     

Consequently, it cannot be that reason is the sole criterion for possession of the right to self.  Let us make clear that what is at stake is not whether animals should be said to have “human rights.” Allowing that such rights exist, it is clear that no animal could possess them, being that animals are not human. But what are human rights if not “natural rights?” and if those rights are natural, adhering to us through principles supposedly universally valid, how can we draw any such distinction? The right to self is the right to self, qualification notwithstanding.