The Storytelling Brain: Confirmation Bias, Reason, and the Architecture of Thought
In their fascinating book The Enigma of Reason, cognitive scientists Hugo Mercier and Dan Sperber challenge the conventional view that confirmation bias is simply a flaw in our reasoning processes. Instead, they argue that what is typically labeled as confirmation bias is more accurately a "my-side bias"—a predisposition to defend one’s own beliefs in social contexts. Far from being a defect, this bias may have evolved to serve a vital social function: helping individuals advocate for their views during discussions, which in turn promotes more effective group decision-making than isolated reasoning would allow.
To illustrate this idea, the authors draw a comparison between human reasoning and the work of a defense attorney. A lawyer’s responsibility is not to uncover objective truth, but to defend their client’s interests by scrutinizing accusations, crafting counterarguments, and presenting favorable evidence. This approach parallels the way people reason in everyday life—selectively emphasizing information that supports their perspectives.
However, this analogy also highlights a structural weakness in the legal system. The fairness of judicial outcomes often depends less on the facts of the case than on the quality and expense of legal representation. Wealthier defendants, who can afford better lawyers, may achieve more favorable outcomes regardless of their actual guilt or innocence. Mercier and Sperber do not dwell on this flaw, but they appear to accept the legal system’s adversarial structure as sufficiently functional to justify the adaptive value of my-side bias. In their view, the courtroom mirrors social reasoning: a competitive arena where opposing arguments help a group (or jury) reach a more accurate conclusion.
Yet it is possible to imagine an alternative legal model—one in which the adversarial structure is replaced by a cooperative search for truth. In such a system, lawyers would adopt a neutral role, investigating and presenting all relevant evidence objectively, rather than acting as advocates. The jury would then deliberate over this balanced and potentially ambiguous set of facts to reach a verdict. This shift in legal structure invites broader reflection on the roots and implications of confirmation bias.
Beyond its social utility, confirmation bias may also be tied to fundamental features of how the brain processes information. Many neuroscientists argue that the brain functions less as a passive recipient of data and more as an active filter. Rather than processing the full complexity of our sensory environment, the brain prioritizes, organizes, and simplifies information into manageable, coherent mental models.
In this way, experiencing reality becomes similar to constructing a narrative. We choose particular details, emphasize certain elements, and shape stories that are emotionally resonant and easy to remember. Because these narratives are formed primarily for ourselves, they are heavily influenced by prior beliefs and cognitive limitations. Confirmation bias, then, can be seen as a byproduct of this internal storytelling mechanism.
This tendency is further reinforced by the social nature of human cognition. Stories—whether individual interpretations or cultural narratives—gain influence not necessarily because they are true, but because they are compelling. Those that align with shared values or evoke emotional responses are more likely to be remembered and repeated. As a result, our understanding of reality is shaped both by internal cognitive processes and by the external social environment. Whether this mechanism enhances group survival is a question answered only over long evolutionary timescales.
Taken together, these insights suggest that confirmation bias could be seen as part of a broader "simplification bias," a necessary adaptation to navigate a complex world with limited cognitive resources. While simplification enables efficient thinking and decision-making, it also constrains our ability to engage with nuance and complexity. Developing our capacity to entertain diverse and even conflicting perspectives can help mitigate these constraints. By doing so, we rely less on oversimplified mental models and approach a more accurate, multifaceted understanding of the world. In the end, the internal coherence we seek—the narrative that helps us interpret reality and define our sense of self—is not only crucial for communication and decision-making but also central to our experience of being human.