Cautiously optimistic rationalism may not be cautious enough.

May expresses optimism about the source, content, and consequences of moral judgments. However, even if we are optimistic about their source (i.e., reasoning), some pessimism is warranted about their content, and therefore their consequences. Good reasoners can attain moral knowledge, but evidence suggests that most people are not good reasoners, which implies that most people do not attain moral knowledge.