He said:

“Among them are the opinions called ‘praiseworthy,’ which we sometimes single out with the name ‘well-known,’ for they rest on nothing but widespread acceptance. Suppose a person were left with nothing but his bare intellect, his faculty of estimation, and his senses; suppose he had never been trained to accept these judgements, that frequent induction from many particulars had not impressed a strong opinion upon him, and that he did not draw upon the humane qualities implanted in his nature—mercy, modesty, dignity, zeal, and the like. In that case he would not judge according to reason, estimation, or sense that stealing another’s property is vile or that lying is reprehensible and should not be committed.”

He went on:

“Of the same class are those notions that spontaneously occur to the imagination of many people. None of these directs the untutored mind. Were a man to imagine himself created all at once, fully rational, having heard no instruction and having yielded to no emotional impulse or innate disposition, he would pass no judgement on such matters at all; ignorance of them or suspension of judgement would remain possible for him. Not so with his judgement that the whole is greater than the part.”

These well-known propositions may be true or false. When true, they are still not to be counted among the first principles and the like, for they are not self-evident to the primal intellect except after deliberation, even though that intellect may approve of them. What is true is not necessarily praiseworthy, nor is what is false necessarily repugnant: something repugnant may be true, just as something praised may be false.

The well-known propositions arise either from obligatory duties, from disciplinary norms established for the common good that agree with the divine laws, from ingrained dispositions and emotional reactions, or from inductive generalizations. Each of these may be taken in an absolute sense or in relation to the practitioners of a particular craft or science.

Al-Rāzī, in his commentary on the Ishārāt, sets out the distinction between intellectual first principles, well-known propositions, and estimative propositions, saying: “The well-known resemble the first principles, yet the difference is obvious, for the first principles…”