To under­stand human nature, I focus on human lan­guage and what it can reveal about how we think. Unlike oth­er ani­mals, humans can com­mu­ni­cate an infi­nite num­ber of thoughts through lan­guage. And one rea­son that lan­guage is pow­er­ful is because we can use each of our words flex­i­bly, with sev­er­al dif­fer­ent mean­ings.