 Generics have proved quite difficult to analyze semantically. For example, “dogs are mammals” seems to require for its truth that all dogs be mammals. “A tiger is striped” or “ravens are black”, however, are somewhat more forgiving, since they are compatible with the existence of a few stripeless tigers and white albino ravens. “Ducks lay eggs” and “a lion has a mane” are more forgiving still; these generics are true even though it is only the mature members of one sex that possess the relevant properties. Notice, however, that we do not accept “ducks are female”, even though every egg-laying duck is a female duck. Finally, we accept “ticks carry Lyme disease”, even though very few ticks (approximately one percent) actually have the property, while also rejecting “humans are right-handed”, when over ninety percent of humans are right-handed.