Why Do Humans Reason?

A recent paper published in Behavioral and Brain Sciences has been getting a lot of attention.  It covers a very interesting topic:  Why are humans so bad at reasoning in some contexts, yet so amazingly good in others?  It’s argued that human reasoning was not designed to help us discover the truth; it was designed by evolution to help us win arguments.  Our reasoning faculties so often lead to poor outcomes, not because we are bad at it, but because we have a strong tendency to seek justification for our beliefs and actions instead of the truth.

Here is the abstract.

Abstract: Reasoning is generally seen as a means to improve knowledge and make better decisions. However, much evidence shows that reasoning often leads to epistemic distortions and poor decisions. This suggests that the function of reasoning should be rethought. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade. Reasoning so conceived is adaptive given the exceptional dependence of humans on communication and their vulnerability to misinformation. A wide range of evidence in the psychology of reasoning and decision making can be reinterpreted and better explained in the light of this hypothesis. Poor performance in standard reasoning tasks is explained by the lack of argumentative context. When the same problems are placed in a proper argumentative setting, people turn out to be skilled arguers. Skilled arguers, however, are not after the truth but after arguments supporting their views. This explains the notorious confirmation bias. This bias is apparent not only when people are actually arguing, but also when they are reasoning proactively from the perspective of having to defend their opinions. Reasoning so motivated can distort evaluations and attitudes and allow erroneous beliefs to persist. Proactively used reasoning also favors decisions that are easy to justify but not necessarily better. In all these instances traditionally described as failures or flaws, reasoning does exactly what can be expected of an argumentative device: Look for arguments that support a given conclusion, and, ceteris paribus, favor conclusions for which arguments can be found.

Though we all dream of a world in consensus, it would be detrimental to our species and future progress.


3 thoughts on “Why Do Humans Reason?”

  1. I suspected this for a long time. I often wondered why people are so smart and so dumb at the same time. It tells me that human logic has self-serving biases, especially in social contexts.

    However, now that we know people have this bias, couldn’t we actively improve ourselves, so as to counteract this blind spot? You said,”Though we all dream of a world in consensus, it would be detrimental to our species and future progress.”

    In some ways it would, but I think people do need to be aware of their own confirmation biases if they ever want to see reality more completely. Perhaps we need to have competition to advance society, but people sorely need to listen to each other more, rather than just argue their own views.

    1. Hey Kristina,

      I apologize it took a few days to respond. I just bought a new computer and have been spending most of my free time getting it set up.

      I wish there was an easy way to make people aware of their “blind spots” without offending them, but in real life I’ve never found this to be possible. My family consists of very devout religious believers, and they live in their own world. If you try to bring up even rudimentary arguments which go against their worldview, they get angry, extremely defensive, cross their arms, and feel you’re a mouthpiece for the devil.

      They talk about the God of this universe being a being of pure love and goodness, but then you point out all the evil things in this world, such as natural disasters and disease, and they overlook it. Those are facts that don’t fit into their worldview and are simply ignored. Even worse, they’re led to a very naive mindset suggesting that when these bad things do happen, it’s due to the “sins” of mankind, and must be divine punishment from above. My family believes that if they doubt even the slightest phrase in the Bible, they’re on their way to hell. Their scriptures tell them to accept the truth of their holy book with the mind of a little child, and to never question any of it. Faith is the highest virtue. How exactly do you deal with that? I’ve found it to be impossible in practice. I simply try my best to avoid conversing about religion.

      I see confirmation biases in others all the time and always find them difficult to bring up. The most common confirmation bias I encounter is this one: If they’re happy, they’ll only see good things around them, always try to cheer everyone up, and oftentimes seem oblivious to the suffering around them. Others who are depressed only seem to notice everything that’s wrong in the world, continually seeking reinforcement for their sadness. They seem to want a justification for why they’re sad. I say this simply as an observation, with no moral judgements involved. Bertrand Russell was well aware of this phenomenon. To quote him, “The man who is unhappy will, as a rule, adopt an unhappy creed, while the man who is happy will adopt a happy creed; each may attribute his happiness or unhappiness to his beliefs, while the real causation is the other way round.”

      On my blog, I try to present the wonders of the universe and the things that make me happy, but I’m also not shy about bringing out the evils all around us. I try to be balanced with it, but am not always successful.

      I oftentimes see confirmation biases in people regarding the economy. Pro-capitalists, such as libertarians, seem unable to notice true market failures. They come up with elaborate justifications for the evils and say that if only the government wouldn’t have imposed such and such a regulation, or if we hadn’t subsidized such and such a market, and so on and so forth, then things would be just fine. On the other hand, socialists and many progressives oftentimes seem blind to the virtues of capitalism. They speak of the evil corporations, but then happily go sipping their coffee at Starbucks, seem to enjoy their afternoon toying with their Apple laptop, talking on their iPhone with friends, while all this information is processed by Cisco network equipment over corporate information networks.

      I’ve found that as long as people aren’t dogmatic and are able to listen, if you present solid evidence based on empirical and historical observations, then they will listen, or at least sit and seriously consider what you’re saying. But if you deal with religion or anything dogmatic, you get nowhere. I think arguments devolve into yelling and go nowhere when solid evidence isn’t being presented. But once again, in practice, especially in regard to social issues, solid evidence is very difficult to come by. People are very touchy about moral issues, and sadly those are the things most difficult to have solid arguments for/against. What sort of evidence do you present to suggest sex before marriage is wrong? If someone was to ask me about the issue, I would start discussing evolutionary psychology and say why humans have such touchy feelings about sex, but would ultimately leave the question open-ended.

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