World knowledge can be divided roughly into two parts. GENERIC KNOWLEDGE is what people tacitly know about space and time, the basic physical laws, natural kinds, manifactured artifacts and their functions, and so on. People normally assumed that generic knowledge doesn't vary much from person to person; they believe that a large core of it is shared by friend and stranger alike. PARTICULAR KNOWLEDGE, however, is what people tacitly know about particular or individual entities - particular objects, events, states, and processes. Particular knowledge depends critically on a person's history. The particulars that one person knows - his parents, his experiences yesterday, and the person to whom he has just talked - won't necessarily be particulars that the next person knows.
- Clark & Clark (2004), a pag.155