 From [Commentary on De Interpretatione] 193.3–19 and quotations in Maimonides, we know that al-Fārābī claimed, against Galen, that logic with possibility statements is useful in practical arts where actual outcomes have to be predicted, such as medicine, agriculture, and navigation (Schacht &amp; Meyerhof 1937: 67). This looks at first sight like a confusion between possibility and probability. But more likely al-Fārābī believed that the laws of modal logic could be tweaked so as to work with “Probably” in place of a modal operator. In fact al-Fārābī does say at [Demonstration] 44.20–22 that in many of the arts, “Necessarily every A is a B” and “Most As are Bs” are treated as equivalent. (But wouldn’t this correlate “Probably” with “Necessarily” rather than “Possibly”? Al-Fārābī is not here to answer the question.)