Simon works mainly on all areas of moral philosophy with interests in aesthetics, epistemology and political philosophy. He has previously written about many topics including thick evaluative concepts, reasons, values, and methodology in moral philosophy.
He has two current projects. First, what is the relationship between reasons and values? When we say that we should act for a reason and think that the act has a certain value, which, if either, of the reason or the value of the act, should be seen as fundamental, and why? Simon thinks that neither is fundamental, but that raises questions about the nature of reasons and values, and how they should both be conceived. Secondly, what is the nature of, and the relationship between, the practices of agreement and disagreement across a range of areas, such as law, art, science and everyday life? How do these practices differ from mere coincidence and mere difference? To what extent does one have to agree on the terms of a debate in order to have a meaningful disagreement? How should we treat the beliefs of those whom we respect but disagree with? This is a joint project with Dr Stephen Pethick in Kent Law School.