Today humanity is reaching new heights of scientific understanding—and also appears to be losing its mind. How can a species that developed vaccines for Covid-19 in less than a year produce so much fake news, medical quackery, and conspiracy theorizing? We actually think in ways that are sensible in the low-tech contexts in which we spend most of our lives, but as Steven Pinker points out in this wise and funny assessment, we fail to take advantage of the powerful tools of reasoning like logic, critical thinking, probability, correlation, and causation.