The banality of evil (a phrase coined by Arendt) suggests that evil acts often arise from a failure to think critically rather than from an intrinsic evilness. This gave rise to the argument that Hitler was not the only person to blame for the Holocaust, but that the entire German population bore some responsibility. In Eichmann’s defense against Arendt, he argued that he was simply following orders from his superiors as a government employee. But what does acting critically actually mean? If critical thinking is not objectively defined, then Arendt’s argument weakens. If Eichmann, for example, were a mentally deranged person who lacked any critical-thinking skills (let’s say there were a general consensus on that diagnosis), then he could not be guilty of his crimes and would, in fact, have simply been following orders from higher-ups in the bureaucracy. Wikipedia defines it as follows: “Critical thinking is the process of analyzing available facts, evidence, observations, and arguments to reach sound conclusions or informed choices.” But this definition is again vague, because what constitutes an informed rather than an uninformed choice? In general, we do not have complete information when deciding how to act (when voting, for example, do you really know your candidate?). DFW, in his remarkable graduation speech “This Is Water,” said: “Two young fish swim past an older fish who asks, ‘Morning, boys. How’s the water?’ Later, one young fish asks the other, ‘What the hell is water?’” This is a cartoon to show that we do not realize the most fundamental realities of our environment. In a way, critical thinking and “This Is Water” are related because, most of the time, we do not think about our actions; instead, we think that we think, which is what makes it so difficult. One way, perhaps, to explain why this is hard is to consider alternative decisions when given a choice. In a typical day, I make around 10 decisions that are actually uncertain and probably an infinite number that are autonomous. One way to think about DFW’s speech is to increase autonomous decision-making—for example, by reducing my anger when someone cuts me off in traffic. But this is hard, often because we have finite time. When I wake up in the morning, I cannot debate with myself about whether getting up at 7 a.m. is worthwhile, let alone whether doing a Ph.D. is worthy of my life. This debate, especially about the Ph.D., could go on for an entire day, which is ironic because debating the topic would make it less likely that I would finish my Ph.D. on time, making it less worthy of my life. So maybe there is a state of efficient critical thinking in which I think about things that are worth thinking about but that I have not yet considered thinking about (sorry for the mouthful); but, again, this is a subjective choice, which means there is no satisfying conclusion to this paragraph.