Why opinion trumps facts

Humans are lazy. We do what we can to protect our daily allotment of thinking resources - and that means trying not to invest too much energy into thinking if we can get away with it. The reason why we do this makes evolutionary sense. Why invest limited brainpower into an activity when you might need that later on that day for an even more crucial task?

We even have a somewhat lazy term for a person who is doing this – a cognitive miser (Fiske & Taylor, 1991).

If our thinking resources are capped (and psychologists suggest they are) we should try to keep some thinking resources available just in case we need them later on. So, in a binary choice between delving into reams of scientific journal articles or listening to an opinion many humans would choose listening to an opinion. That’s because opinions are relatively easy to understand. Nobel Prize-winning social psychologist and psychology professor Daniel Kahnemann summarised the science of these categories of thinking in his book Thinking Fast and Slow, explaining that there are two types of thinking – type one which is intuitive, quick and easy to engage, and type two which is slower, takes more effort to operate and is more rational (Kahnemann, 2011).

Without any hint of irony, Instaread Summaries has produced a 30-minute summary of it to cater for people too lazy to read the 504-page version, but given the topic I’m tipping your type two brain would still get a fair work-out.

Chaiken (1980) and Eagly & Chaiken (1984) showed that people develop clever little work-arounds so they can use their type two brains and keep type one power in reserve. Petty & Cacioppo (1986) took this concept further and developed what is known as the Elaboration Likelihood Model (ELM) of Persuasion. If you’re wondering what the strange graphic the top of this site is all about, that’s what this is. ELM suggests that one of the little workarounds people develop in preference to using their type two brain is to find someone they trust and listen to what they have to say about a difficult topic (among many others).

Of course, that's not to say that everyone will prefer opinion over hard data and everyone will want hard data some of the time. Depending on whether you’re heavily and personally invested in a topic, whether you have enough mental ability to process a difficult topic you might seek out an opinion leader rather than investigate all of the the facts for yourself.

And that’s why more people listen to people like Andrew Bolt than read the data from the Intergovernmental Panel on Climate Change. It also helps to explain Donald Trump's current popularity - at least among Republican voters. But before you criticise these people for being lazy, remember that you’re often lazy too. Just think about the last time you put in your football tips – I bet you came up with your own clever little workarounds rather than use statistical analysis.

And that's the danger for Americans in the coming presidential election. While Trump might be unappealing to those who carefully weigh the facts and the merits of their choice, large numbers of voters don't do this and use peripheral information instead.


  • Chaiken, S., 1980. Heuristic versus systematic information processing and the use of source versus message cues in persuasion. Journal of Personality and Social Psychology, Volume 39, pp. 752-756.

  • Chaiken, S. & Eagly, A. H., 1984. Cognitive theories of persuasion. In: L. Berkowitz, ed. Advances in experimental social psychology. s.l.:Academic Press.

  • Fiske, S. & Taylor, S., 1991. Social Cognition. Second ed. New York: McGraw-Hill.

  • Kahnemann, D., 2011. Thinking Fast and Slow. First ed. London: Penguin.

  • Lau, R & Redlawsk, D. Advantages and Disadvantages of Cognitive Heuristics in Political Decision Making. American Journal of Political Science 45(October), pp. 951-971

  • Petty, R. E. & Cacioppo, J. T., 1986. The Elaboration Likelihood Model of Persuasion. Advances in Experimental Social Psychology, Volume 19, pp. 123-205.