Software was supposed to radically improve society. Outdated mechanical systems would be easily replaced; social media platforms like Facebook would bring people together; and generative AI would solve the world's greatest ills. Yet in practice, few of the systems we looked to with such high hopes have lived up to their fundamental mandate. In fact, in too many cases they've made things worse. How did we get to this point? In Fatal Abstraction, Darryl Campbell explains that the problem is "managerial software" programs created and overseen not by engineers but by professional managers with only the most superficial knowledge of technology itself. A former tech worker himself, Campbell shows how managerial software fails, and when it does what sorts of disastrous consequences ensue, from the Boeing 737 MAX crashes to a deadly self-driving car to PowerPoint propaganda, and beyond. Yet just because the tech industry is currently breaking its core promise does not mean the industry cannot change. Campbell argues that the solution is tech workers with actual expertise establishing industry-wide principles of ethics and safety that corporations would be forced to follow. Fatal Abstraction is a stirring rebuke of the tech industry's current managerial excesses, and also a hopeful glimpse of what a world shaped by good software can offer.