The principal line of ancient and medieval argument about what makes women different from men comes down to what women cannot be, not so much because they are to be morally despised (though they may be) as because systematic and thoughtful reason, logic, and science make inescapable the conclusion that women cannot be male. That seems like a tautology until one makes a project of applying reason and logic to the task of understanding under what circumstances the not-male ontological condition of women could be sensibly and logically determined to identify them as both inferior or dangerous. That circumstance must be a mind-set that assumes the male, as rational and/or moral being, to be the standard against which all manner of sentient existence is to be measured. In a broad sense, that assumption valorizes the potentialities of human reason and physical strength, or, from the medieval point of view, the Creation of humankind--no base motive, to be sure, but a celebration of the gift of life. And what greater testament is there to human potential than the manifestly superior physical strength of males?
If what is so plainly evident is taken as the point of departure for analysis of creaturely attributes of being and behavior, then what is male must be the standard, and what is female, in all its demonstrably echo-like physical presentation, must be what has been abstracted from the standard. From that perspective, Aristotle's variable evaluation of semen and the menses makes perfect sense, and his ignorance of nidation and the ovaries is just so much detail. Evolutionary biology long since overtook Aristotle's careful articulation of the obvious, but if the male is taken as the highest and best expression of life, then reasons must be found to explain how that came about. It is on that basis that Aristotelian logic is brought to the enterprise of explaining life, and it is on that basis that logic dictates that semen is both generat...