One of the philosophically most interesting aspects of the Mohist concern with doctrine is their explicit discussion of criteria for evaluating doctrine in the "Against Fatalism" chapters. The "Three Tests of Doctrine" are introduced as the "standards" or "gnomons" (yi) without which doctrinal disputes become futile. As version C puts it: "To expound doctrine without first establishing standards (yi) is like telling time using a sundial that has been placed on a spinning potter's wheel." The consequence is that the dispute will be interminable.
Although each version of "Against Fatalism" lists three "Tests," the lists differ and a total of four distinct "Tests" can be identified:
Conformity to the Will of Heaven and the Spirits -- this criterion is mentioned only in "Against Fatalism" B but forms the subject matter of the "Heaven's Will" chapters. In those chapters, we can also find the claim that Heaven's will is to Mozi like as "the compass is to a wheelwright or the setsquare is to a carpenter." Just as the wheelwright and carpenter use these tools to evaluate if some object is properly considered round or square, so Mozi is said to lay down Heaven's will as a model (fa) and establish it as a standard (yi) by which conduct and doctrines can be evaluated.
Conformity to the teaching and practice of the ancient sage kings -- Varieties of this "Test" are reported in all versions of "Against Fatalism" and its application can be seen throughout the core chapters.
Good consequences for the welfare of the world (especially the material wellbeing of the common people understood in terms of them having food, shelter and rest) -- Varieties of this "Test" are also reported in all versions of "Against Fatalism" and a lengthy elaboration can also be found in "Frugality in Funerals."
Confirmation by the testimony of the masses' sense of sight and hearing -- This "Test" is listed in "Against Fatalism" A and C, and there are only two certain applications" in the core chapters: in the "Elucidating Ghosts" chapter as part of the proof that providential ghosts exist, and in "Against Fatalism" B as part of the argument against the doctrine of fatalism.