  Re: Mike's response to my post about abortion. First, let us assume some version of physicalism, i.e., that the mind is a physical thing or emerges from purely physical things. In this case, Mike argues that since the chemical and electrical activity that is cause of a mind must precede the formation of the actual mind, there's a gap between when brainwaves, a presumptive effect of this chemical and electrical activity, and when the mind, another presumptive effect of this activity, begin.
Well, no. They're both effects of the same cause; one is not the cause of the other, so neither is logically bound to precede the other. When I turn on a old light, produces a buzz and illumination at the same time. Or close enough to the same time. As far as I know, distinctly human brainwaves more or less appear all at once, on a about the same timescale as an abortion operation. Most of Mike's problem with my proposal of the appearance of distinctly human brainwaves is that I can't prove that they're a proxy for a mind.
He wants a definition of a mind, and a way we can test for it. I'd like to continue to assume a physicalism here, because requiring something other than the brain to produce the mind I don't think will lead to fruitful discussion without bringing theology in. There are many abstract concepts, like "a mind", that defy a facile definition yet are still useful in psychology, ethics, and the law. Take for example willingness . How do you prove the existence of willingness? Well, we don't have direct access to someone's volition, so instead we rely on outward signs. We look for things that always manifest themselves when a person is willing, and don't manifest themselves when a person is unwilling. Rape is having sexual intercourse with someone against their will. How do we determine whether the accuser was willing or not? We can't get direct access to her mind, so we look at things like whether she fought, whether she cried out, etc.
We accept that reports of the accuser shouting, "help me, I'm being raped", implies that she is not willing that the intercourse take place. Outward behavioral signs are accepted as describing interior mental states. It's hard to have a functioning society without this assumption. So to determine what is a good test for a mind, we look for things that always appear when there is a human mind, and for things that never appear when there isn't a human mind.
We don't have to be able to exhaustively describe the precise chain of causation, just as we don't have to be able to describe how the mental state of unwillingness to have sex leads to crying out or biting or clawing. The only thing we've got that nicely correlates with a human mind is human brainwave activity. Nothing that isn't it has it, and everything that is it has it.
And if you still want me to give you a definition of a human mind before we base any law upon it, please furnish definitons for "reasonable" and "willing", words that are important to all sorts of law. My point here is that I can't give you as precise a definition as I think you want, and that the demand you make is too strong to be applied to all the terms we use in law and ethics. 
