Phil posed the following question:
How do you know it's wrong to kill innocent people?
This is an old and venerable question. Plato tackled it in 350 BC and I think he actually had the last word on it for over two thousand years. But not any more.
The religious take on this question is that the only way to know this is through divine revelation; there is no scientifically tenable source of morality. If all there is is a Darwinian survival-of-the-fittest rat race then there is no reason at all to avoid killing innocent people if it provides me with a survival advantage. Abandoning God would therefore plunge the world into anarchy.
But Plato points out a problem with this view. What if God said that it was OK to kill innocent people? Would that in fact make it OK? (And if you are tempted to answer that God would never say such a thing, I suggest you read the book of Joshua.) Or is even God bound by some higher transcendent morality? If so, where does that come from? And if not, how are we to distinguish between God and Satan?
Mankind has been wrestling with this problem for over two thousand years. When progress is that slow it is often fruitful to reframe the problem. So instead of tackling the question of morality I'll instead address a different but related problem on which I happen to be an authority: how do I know that I like chocolate?
This immediately begs a number of anicllary questions: what does it mean to know something? What does it mean to like something? What is chocolate? What is I? Is it in fact the case that I like chocolate? (Is it possible to know something that isn't actually true?)
The difficulty of the problem of morality does not arise because morality is a particular thorny issue, it arises because it's so easy to tie yourself into philosophical knots over anything, even chocolate, that there's hardly any sport in it. It isn't morality that's problematic, it's the quest for absolute certainty. But as a Scientist (in the spiritual sense) I know that I can never be absolutely certain about anything, even my passion for chocolate.
The reason I "know" (or think I know) that I like chocolate is that I have memories of having eaten chocolate in the past and enjoying the experience. These memories are so vivid and their grasp on my psyche is so strong that it often feels like there is an external force (the Hand of the Cocoa God?) overriding my free will and causing me to seek out and consume chocolate even when I know (or think I know) that I probably shouldn't have any more. (Just last night, I swear this is true, my wife made the most delicious batch of chili I have ever had in my life (chocolate is actually one of the ingredients) and I ate so much of it I gave myself a stomach ache. So there I was feeling ill and bloated and I still had a craving for some Nutella!)
Now it is entirely possible that all this is a result of some kind of mental illness, that I don't really like chocolate at all, that I'm simply addicted to it, or that all my pleasant memories of chocolate consumption are halucinations, or that I don't even really exist at all. (I actually consider this to be a very real possibility.) But I'm perfectly content to use Occam's razor to reject all these possibilities and simply say that "I know I like chocolate" is an adequate description of my mental state with respect to myself and chocolate, and to assume that anyone who doesn't understand what I mean by that is either mentally ill or being intentionally obtuse.
I know it is wrong to kill innocent people in much the same way that I know I like chocolate. Somewhere deep in my being there is some transcendant force outside of my conscious experience that drives me to eat chocolate and avoid killing innocents. I have a moral instinct (or a moral intuition) just like I have a chocolate instinct. And so do most people.
Now, it is legitimate to ask where this moral intuition comes from. There are three schools of thought on this. The first is that we humans have the free will to choose moral action, but this is strongly at odds with my personal experience. I find I cannot choose to believe that killing innocents is morally acceptable, even if God Himself were to come to me and say it to my face.
The second school of thought is that we have been endowed with this moral intuition by God (or that we foolishly endowed ourselves with this moral intuition by partaking of the fruit of the tree of the knowledge of good and evil). Regardless of how it came about, having acquired this moral intuition by whatever means, it now transcends even God. This is consistent with Jewish theology which holds that even God is subject to the Law.
The third school of thought is that this intuition evolved. Assuming you accept evolution at all, it is so glaringly obvious that this must be the case that it hardly deserves an explanation. Having evolved a big enough brain to make tools and harness fire it's not a big leap to see how those same brains could be used to realize that teamwork has survival value, and that groups of humans who can be trusted not to kill each other are more likely to survive than those who cannot be so trusted. This view is even consistent with Biblical theology; it explains why, for example, the slaughters described in the book of Joshua are not immoral. It is not necessary for the moral instinct against killing extend to all the members of the species, just wide enough so that there is survival value obtained through cooperation in the group to which the moral edict does extend. As humans have evolved the net has been cast wider and wider, going from family to tribe to city-state, to nation-state, and only now, furtively, to the entire species and even other species as we continue to grow and evolve.
How cooperation and morality evolved has been fleshed out in exquisite detail by Robert Axelrod using computer simulations. This work is less than twenty years old, and represents one of the great advances in the understanding of morality in the history of mankind. This work would not have been possible without the advent of the personal computer.
It is indeed an exciting time to be alive.