James Randerson is a Guardian science correspondent
There was a time when the study of human consciousness was out on the wacky fringes of science. It was the sort of thing you got into if you liked a heavy dose of philosophy, new age thinking and probably soft drugs with your science. As the US philosopher Dan Dennett once quipped: "With so many idiots working on the problem, no wonder consciousness is still a mystery."
The real reason why consciousness is still a mystery, though, is that understanding it is so head-hurtingly difficult. How do you measure someone's personal, subjective experience? Scientists tend to feel very uncomfortable when there is not anything they can see and count.
But the neuroscientist Baroness Susan Greenfield, who is director of the Royal Institution of Great Britain believes that times are changing. She will tell an audience at University College London on Friday night that brain scientists are starting to make progress. She has said:
The big idea is that consciousness is not all or none. You are not just conscious or unconscious. It's like a dimmer switch.
This way of looking at things throws up some difficult questions, because it means that any creature with a nervous system is conscious, to some extent.
"The big problem with saying consciousness comes in degrees is of course there is no clear boundary," Baroness Greenfield says. "There's no clear boundary in foetal development, and there is no clear cutoff in the animal kingdom."
Here we start opening up some serious cans of worms. If a foetus with a nervous system is conscious, how does that affect the abortion debate? Since there is no conscious cutoff between animals and humans, can we justify eating something that shares at least some aspects of our experience of the world?
When I pressed Baroness Greenfield on what the new science means for these questions she was, unsurprisingly, not keen to put her head too far above the parapet.
I don't want to take a side on the abortion debate. I'm not qualified. I'm not a mother. I've never been in that terrible position of having to make that terrible choice, and I certainly don't want to start moralising or pontificating about abortion as such.
All I would say is that it would be an issue that would have to be incorporated into people's thinking on both sides.
A foetus is conscious, but not as conscious as a child. Of course a foetus is conscious because nothing magic happens in the birth canal to turn the lights on.
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