 Before we look at ways of sorting out which features are morally relevant or most morally relevant, it may be useful to note a prior step taken by some casuists, which was to attempt to set out a schema that would capture all of the features of an action or proposed action. The Roman Catholic casuists of the middle ages did so by drawing on Aristotle’s categories. Accordingly, they asked, where, when, why, how, by what means, to whom, or by whom the action in question is to be done or avoided (see Jonsen and Toulmin 1988). The idea was that complete answers to these questions would contain all of the features of the action, of which the morally relevant ones would be a subset. Although metaphysically uninteresting, the idea of attempting to list all of an action’s features in this way represents a distinctive – and extreme – heuristic for moral reasoning. 