The point I made in Part 1 is that rationality itself cannot produce these ethical givens, these axiomatic valuations. Reason is a computational process that can only get off the ground by taking these values as inputs.
For example, consider the axiom of inviolable human worth and dignity. Many of us take human dignity as an unassailable, ethical given. However, there are many who reject this axiom. For example, the animal rights activist and ethicist Peter Singer argues that human dignity is form of speciesism, privileging the pain and suffering of human beings over the pain and suffering of non-human animals. Many atheists have also argued that human dignity, given how it is rooted in the Judeo-Christian tradition, is a concept that should be discarded.
The point here is that a moral axiom many of us assume--human dignity--is both disputed and rejected by many. And the people rejecting it are not (generally) moral nihilists. They simply assume and work with a different set of moral axioms and reach a different set of ethical conclusions.
Regardless, the metaphysical work--assuming some values as inviolable givens--is necessary.
Let me, in this post, give another example of what I'm describing.
In his book Descartes Error the neuroscientist Antonio Damasio describes what he calls the "somatic marker hypothesis." In his work and research Damasio has observed that certain people with damage in the frontal cortex have difficulty making decisions. Specifically, when facing a choice or a decision these patients can make long lists of pros and cons but can never terminate the chain of evaluation to make a choice. They can't pull the trigger on the decision.
Damasio's argument is that these patients can't make a decision because the damage to their frontal cortex disconnected the analytical part of their brain (the part making the long pro vs. con list) from the emotional part of their brain, the part of the brain that cares about all those pros vs. cons.
In short, Damasio has argued that we need more than analysis and rationality to make decisions, we need emotions as well, we need to care. Because if we don't care about Outcome A versus Outcome B how could we ever decide between the two?
Basically, rationality can guide our decision making process, but rationality needs to know what you care about if its going to help you make a decision. Rationality requires some emotional input, otherwise the computational analysis will never terminate.
This is, I am arguing, exactly what happens with ethical reasoning. But instead of emotions and caring we're talking about moral axioms and ethical givens. Naked reason can guide ethical reflection and deliberation. Reason is vital when we face ethical quandaries and predicaments. But naked reason needs to know what, ultimately, we ethically care about. We need to know 1) what we value and 2) how those values rank against each other when they come into conflict. Otherwise, how could you ever make an ethical decision? All you'd be able to do is make long lists of ethical pros vs. cons. Remember those frustrating debates in your college Ethics 101 class? All those interminable ethical debates are just like those patients with damage to the frontal cortex. The conversation and debate never ends. And yet, we have to make moral choices in life. So how to choose? We just have to take some goods as given and/or more important than other goods. And rationality itself can't make that call. There are many rational conclusions to ethical debates. Rationality is just a computational tool. Reason can't tell you, in the end, what to care about. Just sit in on an ethics class.
All that to say, when I describe morality as being metaphysical I'm talking about how rationality is separate from the values we have to input into the system.
These values aren't the product of reason, they make reason possible.
