Generics and Generalization Generic sentences express generalizations about kinds, such as "tigers are striped", "ducks lay eggs", and "ticks carry Lyme disease". I present and review emerging evidence from adults and children that suggests that generics articulate cognitively default generalizations -- i.e., they express basic, early-developing inductive generalizations concerning kinds. Further evidence suggests that these generalizations don't depend solely on information about prevalence. For example, "ticks carry Lyme disease" is accepted, but "books are paperbacks" is not, despite the fact - well-known and acknowledged by participants - that paperbacks are much more prevalent among books than Lyme-disease-carrying is among ticks. Similarly, both adults and preschoolers understand that, e.g., only female ducks lay eggs, yet they are more likely to accept "ducks lay eggs" than "ducks are female". Rather than depending solely on information about prevalence, these primitive generic generalizations are sensitive to a number of content-based factors, such as whether the property in question is dangerous or otherwise striking (as in "ticks carry Lyme disease"), or is an essential or characteristic property of the kind (as in "ducks lay eggs"). This suggests that our most basic means of forming inductive generalizations about kinds is not guided by prevalence alone, but also reflects our nature as learners.