The point here is that, sometimes, context and convention may affect our understanding of even simple statements. The job of a critical thinker is to understand the statements as they were meant , rather than insisting on a purely literal construction. Verification and Evaluation. A more important distinction for critical thinking is between claims that are thought to be verifiable, and those that are presented as evaluative. In this sense, verifiable claims are those that can be confirmed either by observation or by reference to established sources, such as books.
Evaluations are statements of taste and interpretation.
Notice that opinions can be expressed sometimes as statements of verification and sometimes as statements of evaluation. That's a shade of blue. The first two are clearly opinions, but they are expressed as statements of verification , because the issue is whether that is what Willa thinks, not what the color is. Advocatory claims are a little different from verifiable or evaluative claims, in that the latter discusses what was, is, or will be, while the former describes what ought to have been or ought to be. The advocatory form is used for statements about morality, ethics, duty, and so on.