I agree with piddlesworth's point, though I do not find some of the provided examples. In particular, I do not perceive that tool use requires "reasoning", any more than the creosote bush needed to "reason" in developing toxins which repel competitors and predators, or a skunk needs to reason out its response to a threat. All that's required is that there is a feedback loop which differentially rewards some "behaviors" (in a broad or narrow sense) with expanded market share and a mechanism to persist the more successful. DNA appears capable of this for some amazingly complex behaviors, and mimicry can expand upon that capability on shorter timescales.

However, what characterizes these mechanisms is that the feedback loop must include manifesting some alternatives in the physical world within which outside influences provide the differential selection pressure. What we call "reasoning" is distinguished by using internal abstractions to model the physical world. With reasoning, it becomes possible to adopt a behavior based on (at least vaguely) anticipated results which have not yet been tested with real world feedback - something which DNA and mimicry based adaptive feedback loops cannot do. Of course, often this is combined with real world feedback, in that reasoning generates hypotheses which still need external validation.

This "pre-emptive" generation and winnowing of potential adaptive behaviors provides both more diverse and complex options, and a much faster adaptation timescale - obvious evolutionary advantages which do not necessarily involve persuasion.

Chimpanzees do exhibit some primitive "reasoning" when viewing a problem never before encountered and then choosing an appropriate tool based on geometry, anticipated weight, etc - rather than using just blind trial and error. They show evidence of having an internal model of the physical world, by whose rules they can refine possible actions before taking them. This involves no persuasion.

The incorporation of "reasoning" into human persuasion (along with the often stronger emotional components) would be a natural outcome, once the modeling and rule inferring/using mental abilities exist, and once the "environment" for which humans need to optimize survival strategies includes interpersonal and social structures. As such, the human ability to reason may well have been to some degree shaped by the adaptive value of its use for persuasion. But it does not seem credible to credit persuasion with the origins of reasoning, and the case for that purpose having since become the primary driver seems weak.

A great deal of current research shows that reason and rationality play a smaller part in our individual and collective decision making and in our influence upon each other, than we might like to believe. Confirmation bias and the backlash effect greatly limit the impact of even well reasoned arguments, especially in areas felt to be important to survival and thriving within the tribe. A relatively small portion of the populace develops reasoning as a primary tool in explaining the world to themselves and to others; as others have pointed out, contemporary politics demonstrates that amply.

Nevertheless, reasoning is sufficiently survival positive, that it retains at least some influence in persuasion. However, the internalized models and rules of social systems are much harder to reality-test than the models of the physical environment which generated reasoning as adaptive behavior. Very different models of "how humans work" (politically, economically, socially, psychologically) can coexist in the population more or less indefinitely without selective pressure winnowing them to a "most successful" answer. Hence the many political positions which almost never persuade each other despite massive attempts to show by "reason" that their model is more correct - and the very low interest in facts or reason by adherents to the various ideologies.

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Is any of this an advance on Hume?

We’ve probably all had the experience of being on the verge of acting from anger or jealousy, when someone advises us to act reasonably. A typical picture of motivation for action is one in which emotions or desires drive us one way and our reason drives us in another. I have a desire for a tasty but unhealthy dessert, and the voice of reason tells me that I ought not to eat it. I don’t feel like helping at the food bank on Saturday, but conscience tells me that I ought to fulfil my obligation. On this picture, the morally upstanding or prudent person follows the lead of reason, while the morally deficient character caves into desire or emotion.David Hume, in A Treatise of Human Nature, rejects this traditional characterisation of action and its evaluation, offering a remarkable theory in response. He defends the views that the ends or goals of our actions in all cases are given by our “passions,” not by reason, and that the practical role of reason is to figure out how to fulfil these goals. He makes the astounding declaration that “Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them...[Hume] characterised reason not as some mysterious power of grasping truth or of intuiting connections between ideas or thoughts, as some philosophers did, but as the ability either to offer demonstrations or proofs or to make causal inferences.So, first, he shows that reason engaged in demonstration can never be a motive to action. Demonstration is deductive reasoning using necessary truths. Demonstrations are the proofs we use in mathematics and geometry. Mathematics can be applied to the world in the way that engineers use it to solve problems in their work, but knowing the truths of mathematics only, without the addition of a goal or purpose, will not produce a motive to any particular action. Second, Hume asks whether causal reasoning by itself can give motivate action. Causal reasoning, which requires the gathering and assembling of observations, allows us to form beliefs about the world. Do these factual beliefs supply us with motivation to act in particular ways? Say I’m sleepy and I believe coffee can stimulate me. It seems this belief can motivate me to drink a cup of coffee. If so, factual beliefs based on causal reasoning can on their own produce motives. However, Hume notices that such beliefs would have no practical effect on us if we didn’t also have some sort of attraction to the goal achieved by the motivated action – in this instance, staying awake when I’m feeling sleepy. Reason informs me that consuming the caffeine in coffee keeps me awake, but reason didn’t tell me what desires to have. It simply gives me a piece of causal information. Factual beliefs have no influence on our behaviour if they are about things in the world of no concern to us.”

Elizabeth Radcliffe, Ruling Passions

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D, you are quite wrong. My concern is not “winning” a rhetorical argument, my concern is adopting posteriors that are correct and which follow from correct priors.

If a rhetorician is going to use true facts, logic and Bayesian analysis, then he/she can only reach results that I will be in agreement with.

How could classic rhetoricians of 2000 years ago know how to handle science, logic and Bayesian analysis? By making stuff up? Making stuff up that doesn't fit with science, logic and Bayesian analysis and then believing it is not a strength in this context, it is a weakness.

Maybe a rhetorician can convince an ignorant juror, an ignorant judge, an ignorant politician, or an ignorant voter, but they can't convince reality to be different than it actually is. Maybe you want to live in a world of make-believe, I don't.

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The "pure signaling" or "sound & fury" hypothesis ignores what I took to be Mercier & Sperber's main results: if I recall correctly, diverse groups that argued did better than diverse groups that didn't. That is, rather than fighting confirmation bias, M&S found a context where it can be used to advantage. Not just tolerated, but leveraged.

Ignore the dubious theory they wrap it in. The result is both interesting and potentially practical. Indeed, I hope to try to use it in a forecasting challenge. And it gave me some reason to think that maybe the adversarial legal system might have something going for it.

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High-level processes can be logically grouped into categories like components, features and applications - each of these being a little more abstract the previous. The authors are mainly saying that reasoning evolved for the single application of argument, and nothing else. Why would general purpose features like reasoning (and all the modules that might be involved) result in it's exploitation by only a single app? A computer operating system is never designed just to run a word processing program. In fact the idea of word processing or spreadsheeting or whatever will follow the idea of the general purpose computer and O/S, not proceed it. The egg has to come first, but with no intention of making a chicken. That's the tricky bit! I don't think projecting intentions onto evolution is valid. Evolution is relentless, but it's IQ is extremely low. Perhaps 1 IQ point, more likely closer to 0.001.

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I should also add that I'm not trying to bring in some level of self-sealing fallacy within rhetoric, i.e, sealing the act of rhetoric off with ad hoc explanations as to what rhetors would do.

I'm trying to say that rhetors and orators have dealt with this problem for some time (the problem of an audience perceiving rhetoric to be anti-logical, and easy to spot), and have come up with quite cunning systems to manipulate said audience.

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@Lord, got a citation for saying the emotional appeal is the larger appeal? You are incorrect from a rhetorical analysis stance. Douglas Walton's works on informal logic talk about this indepth (as does most rhetorical treatise from classical antiquity to now. Dan Sperber talks about this in his book about relevance as well). The appeal to pathos (emotion) is used typically towards end of a rhetorical treatise. Again, the appeal to logos is the main chunk. Appeal to pathos may be more influential, but it certainly is not the crux of a piece of rhetoric.

@daedalus2u, you are incorrect as well. Rhetoric uses logic depending upon the audience and context (Kairos). If a rhetor or orator was around a bunch of Bayesians, he would take that into account. He would also take into account whether or not you wanted the situation to be one where you wanted a discussion of truth.

You both seem to think that rhetoric is easily spotted, and some anti-logical mode of discourse. It's funny that some of you don't have a grasp on it. I don't mean that in snarky way of course, I mean it in a critical thinking way. If you don't have a grasp on how rhetoric actually is conducted, how are you going to be sure when the time comes that you aren't being persuaded? I mean rhetors and orators have 2000 years of experience in manipulating people. Classical logic, Bayesianism, and science has what? A couple of hundred years at most? They know EXACTLY how to handle the situations that both of you have brought up. They would use your strengths against you, and you'd be nodding in agreement and thinking it isn't rhetoric.

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some details:

The Paper has a central quality to it. It semingly tries to stake off the field.as such. Therefore: It cannot be ignored.

a) 17p main textb) 20p commentsc) 7p authors responsed) 9p references (approx 500! = too much! indicating that you either did not read thoroughly, cannot distinguish the important from the unimportant, or just want to impress. There we are again. Signalling, you are a well-informed specialist in the field of 'reasoning'.)

NO reference e.g. to Lorenz & Lorenzen, who tried to formalize the approach some decades ago. There seemingly is no pressure group to raise your status if you do, so you are save to ignore that line of thinking, if you are not a contrarian or freak.Or were those German guys so embarrassingly low on the ladder of high reasoning, that they can be savely ignored in the first place?(note: I am not associated to this group, just a curious bystander)

My impression, upon further reading into some details of the paper, is not very enthusiastic.(my method, btw, is, to extract some core tenets, and then analyze them word by word, inference by inference, conclusion by conclusion. This takes me a couple of hours, and then I'm finished. If the words change meaning, seemingly to fit the conclusion, I tend to reject the whole. It cannot get better. 'Reasoning' the other way. Message: keep your argument short, else you are deeply in the mud. Especially with such a sensible topic. )

It is quite ironic, that thinkers, who e.g thematize confirmation bias, make themselves dependent on confirmation of their peer-group (ingroup).

Which is typically comprised of, as most presumably know here, groups of approx 500 people worldwide, who are the ingroup in current specialized science and philosophy.(different with climate science and other high-profile areas, where the group is in the 10000nds, and thankfully quite diverse.)

eg. (R3.2, p99):...First, it should be stressed that the argumentative theory does not predict that groups will always make better decisions, but merely that reasoning should work better in the context of a genuine debate. Many other factors besides reasoning can impact the outcome of a discussion – strategic considerations, face saving, and so forth. And reasoning in group can also bring poor outcomes when there is no genuine deliberation....How True.

This is, to be sincere, an important debate which has a long history.On the other hand I am a bit embarrassed, how poorly it seems to be executed.From an outside point of view. (mine)Trust us, we are the experts.NO!Not here!Which does, I repeat, eventually do a great service to climate-change-deniers and other mentally challenged people.

'Reason', as a central tenet of science and philosophy, and everyday life, cannot be worked out, eventually 'decided' upon by a small group of specialist philosophers and psychologists, who feel entiteled to do by their grants.

Won't happen, but even the ambition does not feel helpful, to say the least.

Reminds me a bit on the Herbert Simon debate on the helpfulness of AI-techniques for poets to write better poems some 20 years ago.Where the poets became quite furious.Rightly so.

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well, as has been said already by piddlesworth in a friendly and civilized manner:

...I may be mistaken if you are using uncommon definitions for otherwise common words, but if I’m not, I find much to disagree with in this discussion...


In my domain this type of 'reasoning' simply does not occur.

When Mercier/Sperber assert that...We do argue, however, that reasoning is best adapted for its role in argumentation, which should therefore be seen as its main function. ... (p59)I strongly disagree.There are already terms for that:'Dialogical Logic', Dialogik, Argumentationstheorie.

Obviously there are domains, where this signalling-type of 'reasoning' actually seems dominant.Management, economists, salespeople, politicians, lawyers, eventually even certain philosophers.

'Reasoning' for me is a central tool of problemsolving in the 'real' world.e.g. finding errors in defective systems, and correcting them.

When the opening sentence states...People and institutions usually prefer to explain their behaviors in self-serving and self-flattering ways. ...

then this in my vocabulary is -at best- termed rationalization.It is an AB-USE of the term 'reason'.

It definitely is a 'meta'-topic. And a bad one at that.

There seems to be a good reason why philosophers are bad at repairing cars.But those repairpeople seemingly are just pawns in the dereferencing from the abstract to the 'real' world.Certain philosophers do not make their hands dirty, and even deny the simple people the attribute of 'reason', it seems.

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Lord, I agree, you need to have access to facts and be able to reason in order to be reasoned with. Rhetoric only uses logic as a means to reach a desired end, not to reach an honest or truthful end.

There is a paper by Aumann, Agreeing to Disagree, that shows that Bayesian truth seekers with common priors and common knowledge of those priors cannot honestly agree to disagree. They must either agree or someone is not being honest.

Robin has written a fair amount about this.

Rhetoric is mostly about choosing the priors (i.e. making stuff up or leaving stuff out) that leads to reaching the conclusion that you want. This is fundamentally dishonest.

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No, emotion is the stronger appeal of rhetoric. The reasoning is often just guise for them.

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"People and institutions usually prefer to explain their behaviors in self-serving and self-flattering ways." True enough; and they may be lying, or practicing the Hansonian form of hypocrisy (which is at least *semi*-self-deceiving). But maybe they are merely confabulating--producing a plausible rationalistic explanation--because they really have very little awareness of the sources of their own behavior, and are even unaware of their lack of self-insight. (Admittedly, they may have incentives to remain ignorant, to enable them better to practice *hypocrisy*.)

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So I was listening to this on NPR and some other academic made the useful point that to be selected for the ability to engage in more complex forms of communication must be beneficial to both the listener and speaker. Thus there must be some basis in information sharing that undergirds our advanced linguistic capabilities.

In other words while their might be selection for reasoning ability to influence people to the extent that their current comprehension skills allowed (chimps don't listen much to arguments) this isn't a good explanation for selection of our advanced linguistic comprehension skills. In other words while we see chimps learn tricks like giving false calls to gain advantage over other chimps this alone doesn't provide any selective pressure to develop a more complex linguistic ability. This is a substantial component of human reasoning capability that must have been selected for by it's increased ability to transmit information and allow coordination.

Remember intelligence is very expensive in terms of energy so if increased brain size was of primarily positional benefit (doesn't increase overall group survival) we would expect those bands in which a trait for increased brain size became dominant to seriously suffer relative to other bands. Thus I'm skeptical that this kind of explanation can be the whole story or even the primary story.

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The main chunk of a rhetorical appeal is an appeal to logos (reason). So differentiating between reasoning and rhetoric is probably incorrect, as rhetoric uses logic in a major way.

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Robert, sorry I struck a nerve. I agree there is no shortage of people of any political persuasion that are out of touch with reality. I also agree that what passes for politics has nothing to do with rational discourse but it has everything to do with Robin's hypothesis of “rational” signaling as a way of gaging social support which is the essence of politics.

listeners could be trying to gauge speaker impressiveness, or the social support the speaker can muster in his or her conflicts. Also, listeners could be trying to figure out what they will say in response, in argumentation contests with many possible criteria for who wins. And argument listeners might try to gauge what positions will become accepted by a wider community, to help them decide what positions to personally support.

I do wish that people of different political persuasions would be able to put their tribal loyalties aside and agree on reality, especially when there are real problems that affect us all that need to be addressed and making stuff up is not going to solve them.

However, I think that is the real reason that what passes for rational discourse evolved, as a way to manipulate other people to advantage yourself and disadvantage them independent of what the facts are. In other words, “rational signaling” is “rational” because it is successful at getting you what you want, not because it corresponds with reality.

If everyone was rational, then optimum solutions that maximized benefits for everyone could be reached and Pareto efficiency could (in principle) be approached.

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I may be mistaken if you are using uncommon definitions for otherwise common words, but if I'm not, I find much to disagree with in this discussion. It may be that one force, and even a significant force, in the evolutionary development of the modern capability to reason was the advantage gained by being able to persuade, but this is a far ways off from the same thing as the main or primary function of reasoning being persuasion.

Indeed, this idea would be immediately cast into doubt were a mathematician, or even a mathematics student, included in this conversation. Although it is true that math often includes coming up with arguments to convince others (or even one's self) that a particular statement is true, most of mathematics in practice is concerned with reasoning used as a process to compute an otherwise unknown and unsuspected answer (i.e. seeking truth). This is most of a math student's career in fact: They don't use reasoning to convince but rather to discover; they don't attend lectures or debates between mathematicians to judge the impressiveness of those participating or simply to confirm agreement, but rather to ascertain better reasoning and truth.

A further problem with this discussion is that, in order for reasoning to be primarily for persuasion, it must strictly post-date the development of highly-complex, abstract language, as it is not be possible for persuasion of the sort discussed here to occur without this. But this seems an unlikely history, as some level of reasoning is required even for the invention and use of tools, a skill demonstrated both by non-human primates and certain species of birds, both of which lack the complexity of language to truly persuade by reason alone. These species, though, do demonstrate the ability learn the ideas for these inventions from one another by observation that the inventions do in fact work upon real-world application. Thus there is strong evidence here that, at least pre-language, reasoning was primarily about developing techniques/behaviors which granted advantages in reality (in a way, developing a better understanding of reality, or even "seeking truth"), and developing them more efficiently than had been done previously through intergenerational evolution alone.

Although I'm sure that there can be some definition of "reasoning" for some subset of the world for which persuasion is the main function, my sense is that it would have to be a subset which is designed specifically to exclude those which do not use reasoning mainly to persuade or a definition which by itself lead to this conclusion... so, if that's what this discussion is based on, it's thrust seems less about ascertaining a deeper truth and more of a semantics game.

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