1. Competition (desiring the same thing, which not both can have (IP3 573a))
2. Diffidence (i.e. fearful distrust of one another)
3. Glory (e.g., celebrity, honor)

How these lead to war:

"The first [competition], maketh men invade for gain; the second [diffidence], for safety; and the third [glory], for reputation. The first use violence, to make themselves the masters of other men's persons, wives, children, and cattle; the second, to defend them; the third, for trifles, as a word a smile, a different opinion, and any other sign of undervalue, either direct in their persons, or by reflection in their kindred, their friends, their nation, their profession, or their name." (IP3 573b [Pojman's "option" for "opinion" is a misprint, as is his leaving out the word "to" before "defend."])