I continue to be disturbed by the number of atheits (and some not-so-atheists) seem to think that we can derive moral principles from evolutionary facts -- an idea that that has absolutely no merit whatsoever.
Specifically, I am referring to the idea that the apparent wrongness of such things as murder or rape can be derived from the fact that we have an evolved disposition to view murder and rape as wrong. According to this theory, the survival of our species has been improved by our ability to cooperate with each other. To foster cooperation, evolution has given us a disposition to treat each other with a certain degree of kindness and cooperation, and a genetic aversion to murder and rape. Our current cultural practice of viewing murder and rape as "immoral" is simply a physical manifestation of these evolved characteristics.
It's a nice story. However, it makes no sense.
I have written about this idea a couple of times by quickly skimming a long list of objections to this idea. This time, I would like to look fewer arguments, but examine each in a bit more detail.
Let us imagine that our evolution took a different course. Let us say that a tribe of pre-humans evolved a disposition to kill others who did not look like them. Whenever they came across a different pre-human tribe, if that tribe looked like them, they expressed a genetic disposition toward favoritism. Whenever they came across a pre-human tribe that looked different, they reacted with a genetic disposition to slaughter them and to move "looks-like-me" families into the territory of those who "looks-not-like-me."
I now have a nice story of evolution giving us a particular genetic trait. Could this type of story create a situation in which racial genocide was permissible? Perhaps even obligatory?
Let's imagine that these genetic traits caused "looks-like-mes" to also react with hostility to any other "looks-like-me" who treated "looks-not-like-mes" with any type of affection or even tolerance. This gene made "looks-like-mes" treat other "looks-like--mes" who did not participate in these genocidal wars, or who tried to protect "looks-not-like-mes" just as they would treat "looks-not-like-mes" and added them to the list of beings to be wiped out, leaving more resources for the "looks-like-mes" that have the "hates-all-looks-not-like-mes" gene.
Those who assert that morality can be derived from evolution, it would seem, would have to conclude that "looks-not-like-mes" and "helpers-of-looks-not-like-mes" both deserve to die.
This connection here is important. There is no reasonable doubt that humans evolved. There is no reasonable doubt that our desires have been molded by evolution. Evolution has given us a strong disposition to desire sex, to eat the types of food that helped our ancestors to survive, and to avoid that which causes us pain. Evolution might have given us dispositions towards cooperation and kindness towards others. These evolved desires explain our actions.
However, for any type of evolutionary ethics to make sense, these evolved characteristics must also justify our actions. Morality is not concerned with simply explaining the fact that the are disposed towards a certain type of behavior towards murderers and rapists. Morality is concerned with justifying that action.
As the story about the "looks-like-mes" illustrates, a certain evolutionary story may explain a disposition to wipe out "looks-not-like-mes." However, in order to say that morality can be grounded on ethics, one has to be able to say that these dispositions can justify the behavior, and not just explain it.
Indeed, every single intentional action that any person engages in -- including rape and murder -- has an explanation. It is not the case that every intentional action that any person engages in has a moral justification. The question that ethicists need to answer is, "How do we distinguish between intentional actions that have an explanation only, and those that have an explanation and a moral justification."
The evolutionary ethicist has not given us an answer to this question.
I have read a few scientific articles involving brain scans on people who are then tasked to make moral evaluations. The scientists attempt to map what goes on in the brain when these decisions are made. Some people who comment on these articles state that these scientists are studying morality. Those who say this are making a category mistake.
We could create a similar study in which we asked people to draw logical conclusions. They are given premises and then asked which conclusions follow from those premises. Every time an individual completes the task, we are going to get a brain-scan image of what went on in that task. However, we will have an image regardless of whether or not the reasoning that the subject went through was valid or invalid.
We cannot use the brain scans to determine the validity or invalidity of logical syllogisms. Similarly, we cannot use brain scans to determine the validity or invalidity of moral reasoning. We can use these techniques to understand what people do, but we cannot use these techniques to draw conclusions about what people should do - about how to justify the conclusions that they reach, either as a product of logical or of moral reasoning.
I have argued elsewhere that I think that there is little difference between evolutionary ethics and religious ethics. Both of them appeal to an outside authority that does not exist to create invalid inferences to justify their favorite moral conclusions. Individuals in both groups are equally likely to use invalid inferences from false premises to justify personal preferences that cannot be morally justified.
Against the religious ethicist, I say that if you attempt to do harm to me, you cannot justify that harm by appeal to a deity or to faith. If we allow faith to be counted as a justification for actions, then the 9/11 attacks and every terrorist bombing was justified.
Against the evolutionary ethicist, I say that having a particular genetic makeup may explain why you come after me with an intention to do harm to me. However, your genetic makeup can never support the conclusion that I deserve to be harmed. It may explain your actions, but you need to look elsewhere to justify it.
When it comes to moral justification, we are not going to find our answers in religious faith, nor are we going to find it in evolved sentiments.
Where are we going to find it?
My argument is that we find it in the relationship between malleable desires and all other desires regardless of whose they are.