Here is an interesting conversation between Julian Baggini, who writes splendid popular books on philosophy, and Lawrence Krauss, a scientist who recently wrote a book arguing that physics can explain why there is something rather than nothing. It’s a civil but short dialogue, with some well-expressed disagreements. An excerpt:
Baggini: But if we want to know why someone made a sacrifice for a person close to them, a purely neurological answer would not be a complete one. The full truth would require saying that there was a “why” at work, too: love. Love is indeed at root the product of the firings of neurons and release of hormones. How the biochemical and psychological points of view fit together is clearly puzzling, and, as your aside on free will suggests, our naive assumptions about human freedom are almost certainly false. But we have no reason to think that one day science will make it unnecessary for us to ask “why” questions about human action to which things such as love will be the answer. Or is that romantic tosh? Is there no reason why you’re bothering to have this conversation, that you are doing it simply because your brain works the way it does?
Krauss: Well, I am certainly enjoying the conversation, which is apparently “why” I am doing it. However, I know that my enjoyment derives from hard-wired processes that make it enjoyable for humans to tangle linguistically and philosophically. I guess I would have to turn your question around and ask why (if you will excuse the “why” question!) you think that things such as love will never be reducible to the firing of neurons and biochemical reactions? For that not to be the case, there would have to be something beyond the purely “physical” that governs our consciousness. I guess I see nothing that suggests this is the case. Certainly, we already understand many aspects of sacrifice in terms of evolutionary biology. Sacrifice is, in many cases, good for survival of a group or kin. It makes evolutionary sense for some people, in this case to act altruistically, if propagation of genes is driving action in a basic sense. It is not a large leap of the imagination to expect that we will one day be able to break down those social actions, studied on a macro scale, to biological reactions at a micro scale.