In education, active learning is a style of instruction that asks students to learn by experience—e.g., performing their own experiments or exploring a topic in-depth on their own. This is usually in opposition to passive learning—i.e., lecturing—in which information is delivered by an authority to students, who passively take in information.

A medical syndrome “in which a person is oblivious to a physical disability but otherwise doing fairly well cognitively” (34). The syndrome is named after Gabriel Anton, a 19th-century Austrian doctor who treated a woman who had lost her eyesight but continued to insist that she was merely in a dark room. Grant uses this to frame the second chapter as a metaphor for the ways in which we are unable to see our own cognitive blind spots.

Binary bias is the desire to simplify complex problems into two opposing categories. This desire is meant to help us find clarity about difficult problems; however, this impulse can obscure more than it helps. Grant argues that complexifying a problem can help disrupt our overconfidence cycles and push us to rethink our ideas, instead.