The Broken Ladder: How Inequality Affects the Way We Think, Live, and Die (2017) is a nonfiction popular-psychology book written by Keith Payne, an American professor of psychology and neuroscience. In it, he examines the physical, physiological, psychological, and moral effects of present-day inequality, particularly within the United States. Payne broadly argues that inequality has massively widened over the last 50 years, and that this has had profound implications because inequality harms everyone in society, both rich and poor. Payne further argues that it is actually not poverty that matters most but rather inequality, which explains why the United States, an incredibly rich but also incredibly unequal country, has more features in common with poor developing countries than with other developed countries. Drawing on psychological studies, Payne argues that inequality divides us economically and affects how we think, how our bodies respond to stress, how we view politics, and how we work

Payne argues that these changes have occurred for several reasons. First, because humans constantly make unconscious subjective comparisons to others, which causes us to feel poor. Second, we face an evolutionary mismatch between our evolved craving for status and our modern environment of hyper-inequality, which is analogous to the conflict between our evolved craving for high-fat foods and our modern environment of food abundance. Finally, our environment structures our thinking and behavior; high-inequality environments lead us to become more stressed, make riskier decisions, lead less healthy lives, make biased racial judgments, and overall leave us less satisfied with our situation. In turn, these negative outcomes lead to further inequality, creating a vicious cycle.

Payne concludes that the only way to reverse these negative impacts of inequality is to change our environment by reducing inequality. This is not an argument for socialism, nor is Payne biased toward one group over another. Rather, he argues that inequality creates societal problems that hurt the rich just as much as the poor, and so everyone, including the rich, has a vested interest in reducing inequality before these problems worsen.