I think maybe I should add that the influence of our intersubjective knowledge/beliefs/desires - call it culture, I suppose - can be quite deep in defining the norms of behaviour (aka morality). So whether 'morality' is wholely attributable to instinct is subject to discussion. I think it is unlikely. This view has a certain support from the differences in 'morality' between cultures and subcultures, as well as the underlying similarities. (Note I am avoiding any reference to religions here - the point is far more general than individual strands of cultural influence - although obviously some strands are more dominant in certain cultures)
Isn't that the same as saying it is based on our experiences? In other words, learned?
It's awfully difficult to separate all our experiences, evolution, culture, etc. from a distinct rational process.
The irony is that this ability that separates us from other animals is one that not only allows us to make Moral decisions, but Immoral ones. The general propensity is towards more moral, but that is a hard sell, since the baseline is unclear. Without comparing ourselves to animals we have no true baseline (since even our own human history would then be in a vacuum: are we more moral today than 1000 years ago?)
Certainly our actions rule out much obvious gain in morality except in isolated pockets of cultures (that is, crimes against humanity still exist, but you can find moral actions in any culture based on their view of morality.
Even if we take morals as a distinctly linguistic/cognitive/rational process based on reason, it is always in a context of the social group. If morals are strictly "instinctual" (or "god given"), perhaps we only have the capacity to describe our actions, rather than decide.
Perhaps we only reason in order to "apologize" for our behavior; behavior that we would do anyway, despite the reasoning. That is, the difference humans have over other animals is we get to express a running commentary on what we do, though it hardly changes what we do.
Different people will have different reasons for why they are moral: they will frame it in certain langauge, but the truth may be that the reasons are innate, and we simply describe the feeling we have and express it as a desirable quality (since, after all, we would prefer to describe our qualities as desirable).
Even people who are generally considered Immoral explain their actions as moral; and in their paradigm it makes sense.
Hitler was factually wrong about the danger of Jews, but if he were right about the threat Jews faced, he would have been hailed a hero and a Moral Being. As Moses and Joshua are considered (if you accept that they were factually right about the threat).
I am on the verge of calling Morality a product of nothing but evolution (and instinct), but am uncomfortable since it brushes up against Determinism, which, as I have said, I hate the idea, but have seen no good argument against it.
Science has shown that moral behavior can be explained through evolution, and I would also argue that this explains the marginal gains in global moral values, since we are only generally on a path towards some other baseline, though we don't know what it is. I see no way of separating morals from evolution and our intrinsic nature, and the ability to reason doesn't seem to increase moral actions in a person, it only seems to be able to explain ones actions more convincingly.
edit: A thought. It's hard to think of any distinctly Moral act that is objectively Moral. All Good is subjective, there doesn't seem to be any act that is moral on its own. In fact, it seems that we all do generally immoral things, but we can opt out (whether FW or Determined) and it becomes Good.
It hinges on our reasoning (whether before or after) the gain of an action.
Generally, people consider the torturing of children as Immoral (many Xians don't, since many feel that some babies go to Hell, but lets consider them an anomaly!). However, the REASON it is immoral is because there is no gain. To torture an adult MAY be moral if that adult has information that needs to be obtained (so the argument goes.) It is still an immoral act to torture, but it is MORE immoral to hide information that may result in great harm. (Of course, if you are the American POW who has knowledge, you would consider the fire bombing of Dresden a good thing and thus the torture immoral since it is trying to stop a Good.)
I'm taking quite a Utilitarian view, but I still think it is less calculated. It seems more instinctual and then we tally up afterwards and explain the Good that came out of the event. Had Germany won, we would still be tallying up all the Good that had happened and explained it in moral terms (not without caveats, I'm sure. For example, we don't still praise the Spanish for eradicating the Native People of S.A., though, they believed they were ridding the world of evil people who were an affront to God. Likewise, had Germany killed off the Jews to the same level, we would still think it horrible, though, this - I believe - has to do with the natural instinct: Once the threat is reduced to a managable amount, we can afford the moderate amount of Natural morality imbued within us by evolution. Otherwise a threat is a threat and must be eradicated.)
Of course, my ability to sit back and describe it as a Natural process creates a difficult position, since if it is innate, how can I reason about it as if it is separate from myself. I would simply explain it as my rationalizing of it, though it will have no affect on how I act. Or anyone else.
