Did Reason Evolve as a Persuasion Tool?

Many of our informal security systems involve convincing others to do what we want them to. Here's a theory that says human reasoning evolved not as a tool to better understand the world or solve problems, but to win arguments and persuade other humans. (Paper here.)

Posted on June 22, 2011 at 1:40 PM • 37 Comments


Ed BearJune 22, 2011 1:49 PM

Heh. Given the huge amounts of time our species spends bludgeoning each other with everything from fists to nukes, and the comparatively small amount of time spent actually persuading (>90-1), isn't the theory a bit unpersuasive?

fraacJune 22, 2011 2:04 PM

What's the evolutionary advantage of understanding the world? Solve problems yeah, control other people yeah too. We're wild animals with lies on top; nothing more or less. Human action only makes sense in terms of extended phenotypes.

DilbertJune 22, 2011 2:11 PM

So scientists now claim that "reason" is an evolutionary trait? That's like saying our ability to learn math or english is an evolutionary trait. I believe we learn to reason based on our life experience and social interactions, just like we learn to lie.

mcbJune 22, 2011 2:11 PM

From the abstract:

"This suggests that the function of reasoning should be rethought."

Hmmn...this may take a while.

Adam SlagellJune 22, 2011 2:13 PM

I am skeptical since psychology has shown again and again how people are not motivated by reason but instead by emotion and framing.

sbiJune 22, 2011 2:19 PM

@Dilbert: Our ability to learn math or English _is_ an evolutionary trait. That's why only our species is able to do that.
Lying, BTW, also is an evolutionary trait. Only very few species besides our own can do that (with chimps and ravens the most prominent this has been proven for).

Kim DavisJune 22, 2011 2:34 PM

That's an interesting angle on an idea I became familiar with when studying philosophy - that reasoning was really a branch of rhetoric until Socrates and/or Plato started pretending otherwise.

Alan BostickJune 22, 2011 2:53 PM

Money quote: Darcia Narvaez, an associate professor of psychology at the University of Notre Dame and a contributor to the journal debate, said this theory “fits into evolutionary psychology mainstream thinking at the moment, that everything we do is motivated by selfishness and manipulating others, which is, in my view, crazy.”

Arguing with an evolutionary psychologist is like arguing with a creationist or a climate-change denier -- or mud-wrestling with a pig. You wind up covered in mud, as the saying goes, and the pig enjoys it.

AlanJune 22, 2011 3:00 PM

Yeh, that worked really well all through grade school: Attempt to reason -> fist to the face.

WomenFireAndDangerousThingsJune 22, 2011 3:09 PM

Bruce needs to read more Lakoff and Johnson -- as he is bordering on their work as of late. Which is nice to see.

pietJune 22, 2011 3:35 PM

The authors don't seem to understand evolution. What is the benefit of the first few guy's who 'evolved' reason? They have no-one but there close (genetic) relatives to convince, while the un-evolved idiots are immune to their new power... That does not sound like something that can take over a population.

The whole "its there so it must have an evolutionary function" idea is not very reasonable, as many traits are a side effect of something else.
If we really want to go down that road, I'm more in favour of the view that our reasoning skills came about because we wanted to be better at cheating others, and not be cheated ourselves.

Martin BuddenJune 22, 2011 4:24 PM

The article starts "For centuries thinkers have assumed that the uniquely human capacity for reasoning..."

The hypothesis that human reasoning evolved to win arguments is based on the premise that reasoning is uniquely human. So if we can show that there are animals that can reason but do not have language, then the hypothesis is false.

Now I believe there is some research that crows can reason, see http://boingboing.net/2008/09/17/crows-use-causal-rea.html

Or perhaps crows evolved reasoning so that they could win arguments with other crows...

There's also another reason to disagree with the hypothesis - reasoning is actually a very poor way of convincing other people to one's own point of view. Generally if you want to persuade other humans an appeal to their emotions is much more effective than a reasoned argument.

QJune 22, 2011 4:51 PM

This isn't psychology. It's mere theory with no ability to perform a scientific exploration of the theory. In other words, it's philosophy.

Richard Steven HackJune 22, 2011 5:23 PM

Fraac: "We're wild animals with lies on top"

Well said.

Reasoning depends on conceptual processing. Crows can't conceptualize. Much as I hate to quote Ayn Rand, she pointed out in "Objectivist Epistemology" that crows and other animals have been proven to be unable to count much beyond five. They have no ability to conceptualize higher numbers. So the trick where X hunters enter a crow blind and X-Y people leave works.

"to win arguments and persuade other humans"

This is too narrow. The distinguishing characteristic of humans, as well of most or all primates, is their hierarchical mentality. Humans (and most species) are in a constant tug of war between competing and cooperating with the other members of their species for survival resources.

Developing conceptual processing and then reasoning clearly was intended to aid the species in dealing with the basic fear of death which expresses itself in both competing and cooperating. This includes all areas of human interaction. Arguing and persuading are only a small part of that.

The problem with humans is evolution didn't go far enough. As one of Charles Stross' characters put it, "Humans are about as intelligent as can be expected given no evolutionary pressures to go further." Humans are saddled with a brain split between conceptual processing and an overriding fear of death inherited from their primate origins.

As William S. Burroughs put it, humans are like tadpoles who are stuck at being tadpoles.

Which is precisely what Transhumanism is all about: the elimination of human problems by transcending human nature, i.e., specifically this problem of human emotions overriding human conceptual processing as a result of human conceptual understanding of human mortality.

Via the two prongs of eliminating human mortality via technology and eliminating the ability of emotions to override reason, also via technology, this problem will be eliminated.

The result will be entities which cannot die (except by major physical disruption) and would have no fear of death even if they could.

Dirk PraetJune 22, 2011 6:51 PM

Not buying it. They seem to be confusing reason with the art of debate and subsections thereof such as rhetoric and logical fallacies.

WinterJune 23, 2011 2:07 AM

"Here's a theory that says human reasoning evolved not as a tool to better understand the world or solve problems, but to win arguments and persuade other humans."

Persuade other humans? Indeed, to mate.

The most convincing theory I know about the evolution of music, dance, language, and reason is that it all evolved in the service of courtship. Our brains are a peacock's tail.

VlesJune 23, 2011 2:38 AM

I am gonna throw this in:

Reasoning evolved as a persuasion tool, because women realized long ago men have an aptitude for it and it keeps the sex emotion under control, which - as long as he is fed regularly - manages aggression. (the symptom of his testosterone "addiction").

When a man starts reasoning, she knows she has nothing to fear. She'll still be able to perfectly tell him why he is wrong and he is often left flabbergasted, convinced his reasoning is flawed, and then to look for a better argument.


time flies like a bananaJune 23, 2011 3:10 AM

Joseph Conrad wrote:

"For the use of reason is to justify the obscure desires that move our conduct, impulses, passions, prejudices and follies, and also our fears."

In other words to persuade ourselves first and foremost, rather than other people.

DilbertJune 23, 2011 6:19 AM


I disagree. Other animals have the ability to learn math and language skills. Especially other primates (and dolphins) have learned math, pattern matching, even sign language. Learning is a side-effect of higher brain function. Higher brain function is an evolutionary trait, but the ability to learn is a side-effect.

PhillipJune 23, 2011 8:14 AM

I don't buy into this argument about reason at all. As a follower of Ayn Rand and Objectivism, mans ability to reason exists so that he himself can survive.

I require reason to plant and grow crops, nothing which requires persuasion to anyone. I believe man was probably growing crops BEFORE he had to convince someone else to do something.

Reason is also required to craft weapons in order to hunt.

DilbertJune 23, 2011 9:00 AM


The term "Reason" has multiple meanings:

rea·son verb /ˈrēzən/ 
reasoned, past participle; reasoned, past tense; reasoning, present participle; reasons, 3rd person singular present

1.Think, understand, and form judgments by a process of logic
- humans do not reason entirely from facts

2.Find an answer to a problem by considering various possible solutions

3.Persuade (someone) with rational argument
- I tried to reason with her, but without success

You're just thinking of a different definition than is being used in the research.

mcbJune 23, 2011 11:21 AM

@ Phillip

"I require reason to plant and grow crops, nothing which requires persuasion to anyone."

Leave it to an Objectivist to imagine farming is a solitary activity. Unless you plan to collect the seed, till, plant, water, protect, harvest, thresh, and store the grain all by yourself, you are going to need to persuade at least your entire family, if not your entire community, to assist you.

"I believe man was probably growing crops BEFORE he had to convince someone else to do something."

Man probably persuaded Woman to harvest naturally occurring concentrations of edible plants long before he persuaded his hunter/gatherer/pastoralist clan to quit roaming around, plant fields of crops on purpose, and stay put.

"Reason is also required to craft weapons in order to hunt."

And maybe a hominin ancestor discovered the idea of using a stone to crack open marrow bones by accidentally smashing his finger with a rock. Hunting mega fauna was (is) a collective activity, calling for instruction, planning, communication, cooperation, and communal sharing. The development of lithic technology was a trial and error process which involved incremental innovation over many millennia.

Reason as a means to facilitate persuasion among social creatures capable of speech has some explanatory power. I look forward to reading more.

Robert in San DiegoJune 23, 2011 11:38 AM

So reason evolved not to solve problems, but to craft persuasive rhetoric? My gosh, Douglas Adams (Long Dark Teatime of the Soul) was right!

JimFiveJune 23, 2011 12:54 PM

"Reason as a means to facilitate persuasion among social creatures capable of speech has some explanatory power."

Some. But the fact that reason can be used successfully to persuade is different than the idea that reason developed to facilitate persuasion. It is more likely that reason developed as a way to solve physical problems and then extended to solve the problem of "that person won't do what I want".

Dirk PraetJune 23, 2011 1:01 PM

I have found an even better theory: reason evolved to debunk the cr*p we are constantly being told by others (thieves, preachers, politicians et al).

mcbJune 23, 2011 1:21 PM

@ JimFive

Still, it seems like it could create an agreeable feedback loop; successful persuaders reproducing more successfully than those without the reasoning power to figure out how to "get the girl," "lead the hunt," or "be the boss."

Natural history suggests we were highly social animals, critically dependent on accurately recognizing behavioral cues and behaving appropriately in order to thrive, long before we started doing much critical thinking, problem solving, tool making, or physics.

But, as you suggest, it may be an archaeopteryx or the egg problem.

Doug CoulterJune 24, 2011 9:40 AM

One of my favorite lines is that "man is a rationalizing, not a rational, animal".

I think more decisions are made from subconscious emotion, then reason is used to make them look good -- rationalization in action.

I guess that puts me in agreement with most here.
Not that it matters much in a basically irrational world.

If reason worked so well, why do we find ourselves where we are now, in deep doo doo all around the world? Why doesn't the "best man win" in politics?
Why does truth so often fail over a well crafted lie?

A reading of something like "games people play" might be helpful in analyzing apparently irrational behavior to see the hidden payoffs, or it did for me many years ago.

Reason seems to work out fairly well in science and tech, but elsewhere, not so good. If you buy that most of our legal system was reasoned out to profit the practitioners, rather than the customers, reason worked pretty well there too I suppose.

Doug CoulterJune 24, 2011 9:44 AM

Oh, saw that comment above about violence being the last refuge of the incompetent. That's a biggie, and if you read the books -- not necessarily the last refuge of the competent, either (in that case, one Salvor Hardin) -- it's one of those epigraphs that can morph meaning depending on interpretation in a very clever way.

RandallJune 24, 2011 11:53 PM

The popular version of the is argument seems to be 1) being persuasive provided an evolutionary advantage so 2) our brains are wired for it and 3) that leads to mental biases which 4) shape the world today. Each of those pieces could be wrong.

1) Reasoning/argument are pretty recent things in evolutionary terms -- I just can't see a hunter-gatherer 50,000 years ago on the savanna having more kids because (s)he was a good arguer.

2) It's not clear our brains are "wired for" particular behaviors at all, beyond the particular areas most related to evolutionary success (reflexes, mating, eating, etc.). Finer points of how we reason don't seem to be so crucial to survival and reproduction.

3) If we were wired to win arguments, that would seem just as likely to give us the traits good lawyers have, which often include a firm grasp of our arguments' weaknesses and logical fallacies -- in other words, being wired to win arguments might give us *clearer* thinking, not cognitive biases.

4) Evolution isn't destiny even when it *has* shaped us. Clearly we evolved to have as many offspring as possible, yet fertility is declining in the First World and, for that matter, plenty of people are celibate or homosexual. Likewise, even if we were hard-wired to argue well instead of search for the truth, we obviously manage to find some truth somehow anyway, or science and other fields just wouldn't have accomplished what they have.

It's sure useful to recognize people reason with their own particular interests and that reasoning has a social role, but we don't need to lock ourselves into those two scholars' super-specific (and gloomy) story of how we work. In fact, I think there's plenty of evidence around us that people are a lot more flexible and able to reason clearly than their argument suggests.

VlesJune 25, 2011 5:04 AM

2) there's a book called Brainsex by dr Anne Moire which goes to great lengths investigating the effect hormones in early life stage have on the shaping of our brains and how they differ between the two sexes. The role of testosterone and the logical mind of men, and the emotional mind of women. I found it most enlightening.
I would think emotions drive our behavior for they are but signals informing us of our state, needs and desire.

I agree with your conclusion. We are all reasoning here to Bruce's blog posts and each others responses. Why? I don't think we are trying to persuade anyone but perhaps come to a better understanding by listening to everyone's opinion. 1+1=3 right?

AndyJune 25, 2011 5:52 AM

My opion about this is more surival of the luckest. If in a situation (cave time) and you could think of object or food that wasn't in line of sight and come up with a way to catch it or escape danger it would equal more food,more offspring.
If the reasoning was to win arguments, that might mean they we more social maybe not/did moved area, cummcate danges and such.
The luck part is more trail and error, and the group that got more chance had more times for luck to favour them.

Some book mentioned that the link between sub-conious to conoius was a oneway street. If that was the case the thought that you can think with could be halted by the sub-conoius without you knowing that the data isn't slanted or bias(turning machine type logic)

sorry spelling

AndyJune 25, 2011 5:57 AM

A plug to animals.
A story a coulpe of years ago about a pack of dolphins that were swiming around in a circle with a human in the middle, splashing there tails and (maybe noise,echo). Below the person was a shark.
I would say thats advanced reason or process level...a toys/protect/hates sharks

SmithJune 25, 2011 10:40 PM

um... self-refutation? Self-refuting ideas are ideas or statements whose falsehood is a logical consequence of the act or situation of holding them to be true.

AutolykosJune 30, 2011 7:51 AM

I disagree with the theory, mainly because in my experience reason is one of the worst ways to actually win an argument. Even logical shortcuts and fallacies won't work well when used alone. The best method is an appeal to emotions (or personal interest of the others), followed by a rationalization (which can be as fallacious as you like, as long as nobody wants to believe the guys pointing out the flaws). What reasoning does is protecting against this exact tactic - but it even does this poorly, as a short look at election results can show.
A better protection is actually to watch out for people trying to appeal to your emotions - more often than not, they want to cheat you.
But probably this all comes down to our higher brain functions still being in the early beta stage, at best.

Leave a comment

Allowed HTML: <a href="URL"> • <em> <cite> <i> • <strong> <b> • <sub> <sup> • <ul> <ol> <li> • <blockquote> <pre>

Photo of Bruce Schneier by Per Ervland.

Schneier on Security is a personal website. Opinions expressed are not necessarily those of Co3 Systems, Inc..