This certainly sounds like a strange question. In everday parlance, the terms "human" and "person" are taken to be more or less interchangable. But I think there is a very real distinction to be drawn here. Certainly, developments in behavioral and developmental psychology, cognitive science and philosophy support this contention. But what is the distinction? And how can it reformulate the discussion on abortion? I will take each in turn.
The distinction between "humans" and "persons" was introduced by philosopher John Locke. Roughly, the term "human" is a biological concept. It refers to a certain species in a lineage of evolutionary developments. So, by this definition, an individual human is a living body with a very particular material constitution. A "person," by contrast, is "an intelligent thinking being that can know itself as itself, the same thinking thing in different times and places."
So let's unpack this definition a little bit, before turning to the abortion question. When we refer to something as an "intelligent, thinking being" what generally comes to mind? Well, probably that this being has mental states. Namely, that it is capable of formulating beliefs, of judging, descriminating, remembering and anticipating. These are characteristic "mental" or cognitive states. But Locke doesn't end there. He adds that, what is distinctive about a "person's" mental states, is that they can be reflexive -- namely, that these thoughts can be aware of their dependency on the existence of some agent who *does* the thinking. However, the bare existence of an agent who is aware that it is having its own thoughts isn't enough. What is required is that it can "consider itself as itself, the same thinking thing in different times and places." In other words, the occurence of first person mental states must not only belong to an intelligent being, they must somehow constitute a second order awareness of the agent's continued identity over time. That is what a person is.
Now consider these remarks in the context of the abortion question. The most common way of phrasing that question is: "Is the fetus a person?" If so, then aborting that fetus is some variety of "homicide."
Clearly, the fetus is human. It is an individual, biological organism belonging to a particular species. That isn't in question. What is in question, is whether the fetus can be considered a "person" in the relevant respects. Are fetuses capable of meeting Locke's criterion? Well, let's suppose that their neural pathways are sufficiently developed to allow for the occurence of certain sensorial experiences. They might have a rudimentary sense of spatial orientation (rudimentary in the sense that they do not conceptually distinguish between ups and downs, for example). There may be certain gustatory sensations available to them, depending on the stage in their development. However, this is far from satisfying the criterion of a being capable of forming beliefs. Just to be clear, a belief is a mental state that contains a certain propositional content. It is typically about something, and can be expressed that way. These sorts of states are unavailable to fetuses, since langauges are not innate. Even syntactic relations are acquired!
The real issue is in determining whether fetuses are capable of having mental states that are not only reflexive, but indicate diachronic identity. In other words, can they be aware of themselves as persisting through time? I think not. That being said, the abortion issue -- in its ordinary formulation -- seems to be based not on any reasonable evidence, but on emotional and groudless conjecture.
These are just rough thoughts, off the top of my head. No doubt they require refinement. But I am interested in hearing responses.
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