An interesting new book, Aaron Tang’s Supreme Hubris: How Overconfidence is Destroying the Court and How We Can Fix It, prompts this blog post. Tang is a law school professor and former Supreme Court clerk who has developed an explanation for the historically low opinion that the American people have of the Supreme Court these days: our old friend the overconfidence bias. Although most observers believe that the Court’s unpopularity stems from its open partisanship, Tang points out that the Court has at other periods in its history been similarly partisan yet also managed to be relatively popular. He believes the Court pulled off that trick by ruling in more humble ways than we have seen recently.

To quote Tang quoting experts:

Daniel Kahneman defines overconfidence bias as “our excessive confidence in what we believe we know, and our apparent inability to acknowledge the full extent of our ignorance and uncertainty.” Professor Don Moore, one of the nation’s foremost experts on the subject says that one of the most telltale manifestations of overconfidence is being “excessively sure that [we] know the truth.”

Overconfidence is problematic because it leads us to make mistakes we would have avoided had we only possessed a healthier sense of self-doubt. First, overconfidence “leads [us] to be too confident that [our initial] interpretation of the facts is the right one.” Then, having rushed to a self-assured judgment, we quickly write off those who disagree with us as “evil or stupid.” And after ignoring compelling counterarguments that might have changed our minds, we stumble forward with our mistaken judgments. The consequence, Moore explains, is predictable: “Excessive faith in erroneous intuitive judgments [leads us] to make mistakes.”

Too often, these mistakes are enormously harmful. This is why Kahneman has called overconfidence the most damaging of all cognitive traps and why Moore calls it “the mother of all psychological biases.” [p. 74]

Overconfidence is like a gateway drug that leads people to be particularly susceptible to the many and varied psychological heuristics and cognitive biases that plague decision-makers in all realms (and that we feature in various videos). Citing Moore and others, Tang recounts how the overconfidence bias can increase the likelihood that decision-makers will fall prey to, for example:

  • The availability bias, the tendency to misjudge the odds of a future event based on how easily past instances of the event come to mind.
  • The confirmation bias, the tendency to process information in ways that support our preconceptions.
  • Motivated reasoning, the tendency to unconsciously process information to promote goals or interests extrinsic to the decision-making at hand. Motivated reasoning plays a big role in the operations of the self-serving bias.

Tang provides several significant examples of overconfidence sabotaging decision-making by sailors, doctors, CEOs, soldiers, and other nonjudicial actors. His most relevant examples, of course, feature Supreme Court justices. He easily cites examples from both liberal and conservative justices, but some of the best ones come from the famously brilliant and infamously cocksure Antonin Scalia. In a blog post, “Biases of a Supreme Court Justice”, a few years ago, we also highlighted how his overconfidence led to poor decision-making by Scalia.

In a more recent blog post, “Justice Thomas, Conflicts of Interest, and the Supreme Court”,  we noted how Justice Clarence Thomas’s overconfidence led him to fall prey to the self-serving bias and thereby ignore the serious conflicts of interest that he was subject to so that he failed to even consider recusing himself from cases where he probably should have done so (and has started doing now that his many entanglements have come into public view).

Though judges are trained to be impartial and that is their solemn duty, they are just as susceptible to the overconfidence bias (and its follow-on reasoning defects) as regular folks, if not more so. Supreme Court justices’ success in life and in law can lead them to develop unjustified confidence in their own judgment. Tang quotes the famous appellate judge Richard Posner who said that judges “become more confident” over the years because “they have behind them an ever-longer train of decisions that they no longer doubt are sound.”

Tang does not believe that the Supreme Court justices are consciously partisan:

The likelier alternative is that partisanship subconsciously influences the justices’ behavior. On this view, when the justices come across a difficult case, they start by genuinely asking what the law requires. But they are overconfident in their ability to discover an answer in two different, yet equally important ways. First, the justices are too self-assured in their selection of the correct approach to legal interpretation: they believe that they’ve identified the “one right theory” of determining what the law requires when in truth there are multiple plausible candidates for the task. Second, the justices are also overly confident when it comes to applying their preferred interpretive theories to individual cases. For all the reasons just described, this overconfidence leaves them vulnerable to other cognitive traps—and partisan motivated reasoning is chief among them. [pp. 83-84]

The overconfidence bias, says Tang, leads the justices to fail to seriously consider arguments that oppose their own, to take absolute and often extreme positions, and to use strident language to condemn all opposing views.

Tang’s view is that difficult cases on critical issues should be decided on what he calls the “least harm” principle, where the court rules “against the side with the greatest ability to minimize its own harm using the other options at its disposal.” This principle is implemented in three steps. First, decide if the legal question in the case truly involves a difficult question where both parties are making strong arguments. Second, accept the good faith arguments that each side makes regarding the harm they would suffer should the Court rule against them, rather than simply disregarding what one side has at stake. Finally, the Court should “consider[] each side’s options for avoiding the harm it would suffer in defeat, and … rule[] against the side with the greatest ability to do so.” [13-14]

Our interest in the overconfidence bias, of course, is how it can undermine decision-making in the moral realm, just as it does in the judicial realm. Studies show that people generally overestimate their own morality and do not recognize the gap that exists between how moral they think they are and how moral their decisions and actions indicate they actually are. This overconfidence can lead them to go through life just assuming that if they happen across a moral challenge they will respond in a moral fashion because they know they are good people. This can lead them to make moral decisions without careful reflection, without considering other options, and without consulting others’ views. Moral peril follows.

Hopefully, Tang’s book will prompt Supreme Court justices to reconsider their own decision-making and will remind us to be more thoughtful in the moral realm.

Last month, UT philosophy professor and educational legend Paul Woodruff passed away. This was a tragedy for his family and for everyone, really. He was an intellectual giant. It seems fitting to close this blog post with a quotation on the overconfidence bias from Woodruff’s last book:

I would like to believe that I am a good person, one who can always resist moral failure. But that would be self-deception. Moral failure is always a possibility. That is the first great lesson I must make my own: that I am not as good or as wise a person as I would like to believe.



Dan Kahan, “Foreward: Neutral Principles, Motivated Cognition, and Some Problems for Constitutional Law,” Harvard Law Review 125: 1-77 (2011).

Daniel Kahneman, Thinking, Fast and Slow (2011).

Sanford Levinson, “Antonin Scalia was Supreme Court’s Predominant Trash Talker,” Dallas Morning News, Feb. 14, 2016.

Don A. Moore, Perfectly Confident: How to Calibrate Your Decisions Wisely (2020).

Richard A. Posner, “Foreward: A Political Court,” Harvard Law Review 119: 32-102 (2005).

Aaron Tang, Supreme Hubris: How Overconfidence is Destroying the Court and How We Can Fix It (2023).

Paul Woodruff, Living Toward Virtue: Practice Ethics in the Spirit of Socrates (2023).


Related Videos:

Confirmation Bias:

Overconfidence Bias:

Self-serving Bias:


Related Blog Posts:

Justice Scalia:

Justice Thomas: