For don marquis, the generalizations relied upon by both those who oppose and those who favor abortion are

The answer is: Accidental

Don marquis believe that those that disregard abortion tend to make a generalization that the oppositions are immoral while those that favor abortion tend to make a generalization that the oppositions are ignorant.

He believed that these generalization are accidental because it automatically formed with other principles or belief that the holder of opinion have in their life.