A Better Definition of Personhood

I've been thinking a lot about the concept of personhood recently. This was triggered, I think, by some otherwise well meaning scientist on NPR repeating the old canard about science not being able to determine when life begins. My reaction was something along the lines of "hold up, that's just a semantic dodge". Because its perfectly obvious that a fertilized egg is "alive" in the biological sense of the word. The confusion arises from the fact that the scientist meant something other than plain biological activity when he said "life". He was conflating the term "life" with something else, which I'll call "personhood" for lack of a better word. Presumably he understood the distinction, but didn't think that it was worth getting into. Which does a grave disservice to the discussion, I think, because it perpetuates the common view that personhood is equivalent to having human DNA. This view, as far as I'm concerned, is clearly erroneous because it fails to take into account most of those components of "being" that make a person a person. This is the single reason why science can't tell us when personhood beings, because there isn't a consensus definition of "a person". However, presuming that such a consensus definition could be reached, there isn't any reason to think that science couldn't at least contribute to the discussion. So what, perchance, makes a person a person? The elephant in the room which the biological definition is ignoring is self-awareness, though this myopia is understandable to some degree. If you admit cognition as a criteria for personhood then you run into a couple of issues which would, no doubt, be viewed as problematic by traditionalists: 1. Making self-awareness a criteria for personhood "de-personizes" (anyone have a better word?) some life forms (notably embryos and Terri Schiavo) which certain segments of the population would like to have classified as "people". 2. It opens the door to non-human persons. Now, you could make "and have human DNA" a requirement for personhood, but the speciesism in that statement is so blatant that it should be obvious to everyone. The argument can be raised that determination of self-awareness is inherently subjective; by definition only the subject can know with meta-physical certainty that they are self-aware (see Descarte, Renè). However, there are external tests which can serve as reasonable proxies¹:

• Mirror test
• Various metacognition tests

The interesting thing about these tests is that not all animals can pass all of them. For example, it appears that only the Great Apes can pass the mirror test, but apes and dolphins can pass the meta-cognition tests. And then there are some animals, like the Sphex wasp, which exhibit little or no volitional behavior. This would seem to imply that "conciousness" is not a black/white issue, but rather comes in levels or gradations. The neat thing about this approach to personhood is that it provides a rational framework for some practices which we already observer. For example, its really easy to do lab experiments on rats or mice, but regulations for performing experimates on primates, Great Apes in particular, are much more stringent. Presumably thats because we recognize that Great Apes are more "like us" than other animals. Getting back to the central point, however, it becomes apparent that if cognition is used as a model for personhood then science can speak with some certainty to the boundaries of this state. Based on the results of the tests listed above we can assign animals greater or lesser degrees of personhood. We can also narrow the answer to the question of when personhood begins. For example, in humans the machinery for cognition isn't present until at least the 25th week of gestation. So, under a more reasonable definition of personhood, its no longer possible to dodge the question of when personhood begins.

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1 There have been a number of criticisms of these tests in terms of what the results actually mean, but that's outside the scope of this particular post. Let's stipulate for the time being that these tests measure what they're supposed to measure.