The main aim of Part 2 is to explain how the form of the good gives rise to knowledge of forms, the forms in question being of virtues and virtue-related things. This ramifies into discussions of dialectic and mathematics, the ambiguous property 'clearness' (saphēneia), hypotheses, and the non-hypothetical principle. It is proposed that the form of the good is interrogative. This position is defended against philosophical and textual objections, and argued to be preferable to alternatives. There is discussion of why Plato excludes the use of diagrams from dialectic and whether he can allow input from experience. The role of context in the rulers' dialectic is explained, and becomes the basis for explaining why Plato's treatment of dialectic in the Republic remains at the level of a sketch. There is an exploration of the difference between true philosophers and sight-lovers, and of the criteria and scope of 'good' in dialectic. This last discussion encounters the classic problem of the connection between Plato's 'justice in the soul' and just conduct as ordinarily recognized, and a solution to this problem is proposed.

Critical thinking in science and many other disciplines should encompass creative, analytical, practical, and wise thinking. Underlying it are both cognitive processes and dispositions–that is, what a person can do and what a person chooses to do. Critical thinking is both domain-general and domain-specific. The domain-specific elements of it cannot be well captured by general tests of critical thinking. We have found that critical thinking in STEM disciplines involves skills that are quite different from those involved in taking tests of cognitive and academic skills. Some of these skills are generating hypotheses, generating experiments, and drawing conclusions. In our tests of these skills, which we have administered to students at Cornell University, scores on the tests correlated not at all or even negatively with tests of academic preparation, such as the SAT and the ACT. Thus, universities that select future scientists and engineers on the basis of such standardized tests may be choosing the wrong people unless they can assure that those people are good scientific reasoners, not just good takers of analytically-oriented tests.