Fribn "engines" episode 1150
Gould ends his essay with a curious motto. "Human
equality is a contingent fact of history," he says.
"Say that five times before breakfast." Our equality
is a contingent fact of history. By contingent, he
means things might have worked out differently.

I have trouble with this. Which of the dictionar;y meanings do you think he is using?
contingent
adj.
5L contingens, prp. of contingere, to touch: see CONTACT6
1 [Obs.] touching; tangential
2 that may or may not happen; possible
3 happening by chance; accidental; fortuitous
4 unpredictable because dependent on chance
5 dependent (on or upon something uncertain); conditional
6 Logic true only under certain conditions or in certain contexts; not always or necessarily true
7 Philos. not subject to determinism; free
n.
1 an accidental or chance happening
2 a share or quota, as of troops, laborers, delegates, etc.
3 a group forming part of a larger group
con[tin4gent[ly
adv.