In recent decades the debate over the metaethical conclusion from the theory of evolution has intensified. Michael Ruse’s epistemological argument has been taken up by Richard Joyce, Guy Kahane and Sharon Street and formalised into the Evolutionary Debunking Argument:
Causal Premise: Our evolutionary history explains why we have the moral beliefs we have.
Epistemic premise: Evolution is not a truth-tracking process with respect to moral truth.
Metaphysical Assumption: Objectivism gives the correct account of moral concepts and properties.
Therefore,
Moral Scepticism: None of our moral beliefs are justified.
Moral realists have attempted to attack this argument through attacking any one of these premises. In this thesis I will argue that with slight modifications we can justify each of the premises of the EDA and construct a sound argument that will establish moral scepticism. I will justify the causal premise through an inference to the best explanation of the phenomena of moral belief relying on our best currently available empirical data. I will justify the epistemic premise by ruling out any potential relation between evolutionary forces and moral truth. The metaphysical assumption will be justified by turning it into an epistemological assumption and using a reconstruction of G. E. Moore’s Open Question Argument. This will allow us to recreate the EDA into a sound argument:
Revised Causal Premise: Human moral judgements are unavoidably influenced by human evolutionary history.
Epistemic Premise: Evolution is not a truth-tracking process with respect to moral truth.
Epistemological Assumption: Objectivism gives the only justifiable account of moral concepts and properties.
Therefore,
Moral Scepticism: None of our moral beliefs are justified.
I will conclude by pointing out possible avenues for the moral realist to object to the revised EDA I establish. However, I will also point out why each of these avenues is likely to fail and, for the moment, moral scepticism is the most plausible position.
