 On this basis, “probable opinion” (opinio probabilis) became a standard term for a class of propositions held to be true, which humans had to be content with in many fields of investigation. In these fields, human fallibility or the changeable nature of the subject matter precluded full knowledge (scientia), and a lack of religious relevance or accepted theological contentiousness prevented the intervention of faith (fides). The scope of this domain was enormous. In philosophical theory, it was the home-ground for dialectical argumentation and dialectical syllogisms (see Section 4.1); on a practical level, it was regulated by counselors of conscience and lawyers. 