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    Thinking Dictionary

    Motivated reasoning

    What it is

    Motivated reasoning is reasoning that is steered by what we want to be true. When we want a particular conclusion, we tend to use whatever ways of thinking are likely to get us there. But there is a limit. We only go as far as we can build a justification that seems reasonable, to ourselves and to others.¹

    So we go easy on evidence we like and pick apart evidence we don't. Usually we don't notice, because we can always find a reason that sounds sensible.

    It is a close neighbour of Confirmation bias. Confirmation bias is mostly about which evidence we look for and notice. Motivated reasoning is about wanting a conclusion and reasoning towards it.

    Why it matters

    Motivated reasoning isn't lying. People usually believe their own reasoning. That is exactly what makes it hard to spot in ourselves.

    It also isn't something only other people do. Everyone has conclusions they would prefer: about their health, their choices, their politics, and the people they like.

    What studies have found

    Tougher standards for bad news. In one set of experiments, people were given a medical test result. Those who got an unwelcome result were more likely to take the test again, and they rated the test as less accurate. People asked for more information before accepting a conclusion they didn't want than one they did.² Psychologists call this motivated scepticism: being sceptical mainly of things we don't want to believe.

    Politics. In another study, people read arguments for and against political positions. They argued against the ones that opposed their views and accepted the supporting ones without much thought. As a result, their views became stronger. The effect was largest in people who already held strong views, and in those who knew the most about politics.³

    Being good with numbers doesn't protect you. In an experiment in the United States, people who were good with numbers solved a tricky data problem well when it was about a skin cream. When the very same numbers were about gun control, their answers split along political lines. And the split was larger among the people who were best with numbers.⁴ That was one study in one country, so it shouldn't be taken as the last word. But it suggests that skill and intelligence can sometimes supply better excuses rather than better answers.

    Not the whole story. Other research suggests that, when it comes to believing false news, not stopping to think may matter more than wanting a particular answer.⁵ The Misinformation vs disinformation entry covers this. Motivated reasoning is real, but it doesn't explain everything.

    In everyday life

    • Your health. A test result you don't like seems more likely to be a mistake than one you do like.
    • Your purchases. After buying something expensive, you find reasons why the critical reviews don't apply to you.
    • Politics and sport. A referee's decision, or a politician's mistake, looks very different depending on which side you're on.
    • Facts and values. We sometimes argue about facts when what we really disagree about is values. See the Facts vs values entry.

    The common trap

    The first trap is thinking "only the other side does this."

    The second trap is thinking that intelligence or education protects you. It can simply make you better at finding reasons for what you already wanted to believe.⁴˒³

    Some ways out:

    • Use the same standard both ways. Before judging a study, ask: "Would I accept this method if it had found the opposite?"
    • Notice your wishes. Ask yourself which answer you're hoping for. That's where to be most careful.
    • Look for the full picture, not just the evidence you like. See the Cherry-picking entry.

    Try it

    Next time you read about a study whose result you dislike, write down the flaws you find in it. Then imagine the same study had found the opposite. Would you have looked for those flaws?

    Now take a study whose result you like, and check it against the same list of flaws.

    Related concepts

    Confirmation bias · Misinformation vs disinformation · Facts vs values · Actively open-minded thinking · Cherry-picking · Falsifiability

    Sources

    1. Kunda, Z. (1990). The case for motivated reasoning. Psychological Bulletin, 108(3), 480–498. https://doi.org/10.1037/0033-2909.108.3.480

    2. Ditto, P. H., & Lopez, D. F. (1992). Motivated skepticism: Use of differential decision criteria for preferred and nonpreferred conclusions. Journal of Personality and Social Psychology, 63(4), 568–584. https://doi.org/10.1037/0022-3514.63.4.568

    3. Taber, C. S., & Lodge, M. (2006). Motivated skepticism in the evaluation of political beliefs. American Journal of Political Science, 50(3), 755–769. https://doi.org/10.1111/j.1540-5907.2006.00214.x

    4. Kahan, D. M., Peters, E., Dawson, E. C., & Slovic, P. (2017). Motivated numeracy and enlightened self-government. Behavioural Public Policy, 1(1), 54–86. https://doi.org/10.1017/bpp.2016.2

    5. Pennycook, G., & Rand, D. G. (2019). Lazy, not biased: Susceptibility to partisan fake news is better explained by lack of reasoning than by motivated reasoning. Cognition, 188, 39–50. https://doi.org/10.1016/j.cognition.2018.06.011