mercoledì 26 ottobre 2016

Are Disagreements Honest? Tyler Cowen Robin Hanson

Are Disagreements Honest?
Tyler Cowen Robin Hanson
Citation (APA): Hanson, T. C. R. (2014). Are Disagreements Honest? [Kindle Android version]. Retrieved from

Parte introduttiva
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Are Disagreements Honest? Tyler Cowen Robin Hanson*
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I. Introduction
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People disagree all of the time,
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politics, morality, religion, and relative abilities.
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intelligent people
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Disagreements usually persist,
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Nor is disagreement usually embarrassing;
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about what is objectively true,
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people often consider their disagreements to be honest,
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Yet according to well-known theory, such honest disagreement is impossible. Robert Aumann (1976) first developed general results about the irrationality of “agreeing to disagree.” He showed that if two or more Bayesians would believe the same thing given the same information (i.e., have “common priors”), and if they are mutually aware of each other's opinions (i.e., have “common knowledge”), then those individuals cannot knowingly disagree. Merely knowing someone else’s opinion provides a powerful summary of everything that person knows, powerful enough to eliminate any differences of opinion due to differing information.
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Aumann’s impossibility result
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It can cover the age of a car, the correctness of quantum mechanics, whether God created the universe, and which political candidate is more likely to induce prosperity. It can even apply to morality,
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assumption of common priors,
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same information
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same beliefs.
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extreme position that that priors must be common
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opposite extreme position, that any possible prior is rational.
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Are typical human disagreements rational?
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are typical human disagreements honest?
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To consider this question, we do not need to know what sorts of differing priors are actually rational, but only what sorts of differences people seem to think are rational. If people mostly disagree because they systematically violate the rationality standards that
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they profess, and hold up for others, then we will say that their disagreements are dishonest.
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We will tentatively conclude
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II. The Phenomena of Disagreement
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both sides typically believe themselves to be truth-seekers,
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Disagreements do not typically embarrass us.
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high-IQ individuals seem no less likely to disagree
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“the courage of their convictions.”
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Psychologists suggest
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believing that he or she is better than others
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even though people in fact tend to be more influenced than they realize (Wilson, Gilbert, & Wheatley 1998).
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People are usually more eager to speak than they are to listen, the opposite of what a simple information-collection model of discussion would predict
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inclined to believe what they "want to believe."
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For example, most people, especially men, estimate themselves to be more able than others
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Gilovich (1991, p.77) cites a survey of university professors, which found that 94% thought they were better at their jobs than their average colleagues. A survey of sociologists found that almost half said they expected to become among the top ten 3 On the tendency for polarization, see Sunstein (1999).
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People also tend to think more highly of their groups,
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III. The Basic Theory of Agreeing to Disagree
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used Bayesian decision theory.
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simple parable.
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Imagine that John hears a noise, looks out his window and sees a car speeding away. Mary also hears the same noise, looks out a nearby window, and sees the same car. If there was a shooting, or a hit-and-run accident, it might be important to identify the car as accurately as possible. John and Mary’s immediate impressions about the car will differ, due both to differences in what they saw and how they interpreted their sense impressions. John’s first impression is that the car was an old tan Ford, and he tells Mary this. Mary’s first impression is that the car was a newer brown Chevy, but she updates her beliefs upon hearing from John. Upon hearing Mary’s opinion, John also updates his beliefs. They then continue back and forth, trading their opinions about the likelihood of various possible car features. (Note that they may also, but need not, trade evidence in support of those opinions.) If Mary sees John as an honest truth-seeker who would believe the same things as Mary given the same information
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then Mary should treat John’s differing opinion as indicating things that he knows but she does not. Mary should realize that they are both capable of mistaken first impressions. If her goal is to predict the truth, she has no good reason to give her own observation greater weight, simply because it was hers. Of course, if Mary has 20/20 eyesight, while John is nearsighted, then Mary might reasonably give more weight to her own observation. But then John should give her observation greater weight as well. If they can agree on the relative weight to give their two observations, they can agree on their estimates regarding the car. Of course John and Mary might be unsure who has the better eyesight.
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opinions should eventually stop changing, at which point they should become mutually aware (i.e., have “common knowledge”) of their opinions
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They will each know their opinions, know that they know those opinions, and so on.
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disagree is problematic, given such mutual awareness.
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they would each have exactly the same information, and thus should each have the same estimate of the age of the car.
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discussion path of their alternating expressed opinions must follow a random walk.
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"Dutch book" arguments
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These arguments showed that if an agent is willing to take bets on either side of any proposition, then to avoid guaranteed losses, his betting odds must satisfy the standard probability axioms.
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in ordinary practice,
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we know that disagreement is persistent.
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IV. Generalizations of the Basic Theory
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when these assumptions are considerably relaxed.
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We also can relax the requirement that John and Mary be absolutely sure of the things they are mutually aware
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they have “common knowledge.”
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assume only “common belief.”
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Thus John and Mary need not be absolutely sure that they are both honest, that they heard each other correctly, or that they interpret language the same way.
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mental context,
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their style of analysis,
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recent thoughts.
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John should pay attention to Mary's opinion not only because it may embody information that John does not have, but also because it is the product of a different mental context, and John should want to average over as many mental contexts as he can.
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V. Comparing Theory and Phenomena
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assumed that people say what they believe.
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people instead usually lie
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people usually have the strong impression that they are not lying,
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People sometimes accuse their opponents of insincerity, but rarely accept this same label as a self-description.
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Bayesians can easily disagree due to differing priors,
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Does this allow typical human disagreement to be rational?
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To answer this question, we would need to not only identify the prior differences that account for typical human disagreements, we would also have to decide if these prior differences are rational. And this last topic turns out to be very controversial.
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To evaluate the honesty of disagreement, we do not need to know what sorts of differing priors are actually rational, but only what sorts of differences people think are rational.
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VI. Proposed Rationality Constraints On Priors
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An agent's prior describes the probability she would assign to each possible state if her information were reduced to knowing only that she was somewhere in that model’s universe of states.
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In such models, the prior is intended to describe each agent’s actual beliefs at this earlier time.
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how different can rational priors be?
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One extreme position is that no differences are rational
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If John and Mary were witnesses to a crime, or jurors deciding guilt or innocence, it would be disturbing if their honest rational beliefs -- the best we might hope to obtain from them -- were influenced by personal characteristics unrelated to their information about the crime.
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Another extreme position
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one prior is no more rational than another than one utility function is more rational than another.
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If we think we are questioning a prior, we are confused;
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One can accept this premise and still argue that priors should be treated as common.
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differences in terms of differing utilities
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rather than differing priors.
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People who think that some beliefs are irrational are thus forced to impose constraints on what priors are rational.
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For example, technically we can think of a person at different moments in time as different agents, and we can even think of the different mental modules within a person’s mind specializing in different mental tasks as different agents (Fodor 1983). If each different mental module at a different time could rationally have arbitrarily differing priors, then almost any sequence of belief statements a person might make might count as rational. Those who think that some sequences of statements are irrational must thus impose limits on how much priors can differ for agents close in space and time. For example, it is common to require that the different mental modules within a single person share the same prior. Since it is infeasible for mental modules to share more than a limited amount of information with each other, we understand that different mental modules will sometimes give conflicting answers due to failing to share relevant information.
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it is common to require Bayesians to change their beliefs by conditioning when they learn (or forget) information.
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Psychologists explain human belief formation
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attitudes, information, and experiences,
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their mood,
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how a subject was first framed,
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what other beliefs were
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can easily produce an unending supply of independent persistent disagreements.
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How rational are such disagreements?
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Imagine that John believes that he reasons better than Mary, independent of any evidence for such superiority, and that Mary similarly believes that she reasons better than John.
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Such priors are consistent in the sense that what John thinks he would believe if he were Mary, is in fact what Mary believes, no matter who “is” Mary. These priors are also “common” in the sense that everyone agrees about what Mary will think, no matter who really “is” Mary. These priors are not, however, “common” in the sense required for the theory of disagreement. Are such differing priors rational?
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they violate “indexical independence.”
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things like whether the “I” that would ordinary say, “I am John,” instead says, “I am Mary.”
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our ordinary concepts of physical causation,
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For example, how likely John is to be right in his current argument with Mary may depend on John and Mary’s experience, IQ, and education, but given a rich enough set of such relevant features, we do not expect to get more predictive ability from indexical information about who really “is” Mary.
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some theorists use considerations of the causal origins of priors
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If John and Mary have different priors, they should realize that some physical process produced that difference. And if that difference was produced randomly or arbitrarily, it is not clear that John and Mary should retain it.
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In summary, prior-based disagreements should be fully anticipated, and there are many possible positions on the question of when differing priors are rational. Some say no differences are rational, while others say all differences are rational. Many require agents close in space and time to have the same prior, but allow priors to differ at conception.
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VII. Commonly Upheld Rationality Standards
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sequence of statements that is inconsistent
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opinion does not change in response to relevant information.
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common priors for the mental modules within a person,
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people criticize others when their opinions appear to have self-serving biases.
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Consider a school administrator who
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favors his son for a school award, or a judge who does not excuse himself from a case in which he has an interest. Consider a manager who assigns himself to make an important sales presentation, or who uses his own judgment in an important engineering decision, rather than relying on apparently more qualified subordinates.
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Though critics acknowledge that self-favoring belief is a natural tendency, such critics do not seem to endorse those beliefs as accurate or reliable.
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common criticisms suggest that most people implicitly uphold rationality standards
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VIII. Truth-Seeking and Self-Deception
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disagreements rarely embarrass us, and smarter people disagree just as often as others.14
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believing in yourself can be more functional that believing in logical contradictions.
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while unbiased beliefs may be closer to the truth, self-favoring beliefs can better serve other goals.
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The virtues of self-confidence and self-esteem are widely touted (Benabou and Tirole 2002). Parents who believe in their children care more for them, and the best salesmen believe in their product, whether it is good or bad. By thinking highly of himself, John may induce Mary to think more highly of John, making Mary more willing to associate with John. Scientists with unreasonably optimistic beliefs about their research projects may work harder and thus better advance scientific knowledge (Everett 2001; Kitcher 1990).
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Self-favoring priors can thus be “rational” in the sense of helping one to achieve familiar goals,
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Regarding self-deception, people seem more likely to gain the benefits of biased beliefs if they do not believe that they are biased
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For example, a salesman is more persuasive when thinks he likes his product because of its features, rather that the fact that it is his product. And people do seem to often be unaware that they think highly of 22 themselves because of their prior. If Mary asks John to explain his high opinion of himself, John will usually point to some objective evidence, such a project he did well on.
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academics who accept the conclusion that disagreement is irrational still disagree, including among themselves.
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When forced to overcome their self-deception and confront the issue, people consistently choose to continue to disagree.
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The story we have outlined so far, of a widely recognized tendency toward self-favoring beliefs in others, together with self-deception about this tendency in ourselves, is commonly told in psychology and philosophy. Evolutionary arguments have even been offered for why we might have evolved to be biased and self-deceived. 15 15 Many have considered the evolutionary origins of self-deception and excess confidence one’s own abilities (Waldman 1994). For example, truth-seekers who find it hard to lie can benefit by changing their beliefs (Trivers 1985; Trivers 2000). On topics like politics or religion, which are widely discussed but which impose few direct penalties for mistaken beliefs, our distant ancestors may have mainly demonstrated their cleverness and knowledge by inventing original positions and defending them well (Miller 2000).
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This story is also commonly told in literature. For example, the concluding dream in Fyodor Dostoevsky's (1994 [1866]) Crime and Punishment seems to describe disagreement as the original sin, from which arises all other sins. In contrast, the description of the Houyhnhnms in Jonathan Swift’s (1962 [1726]) Gulliver’s Travels can be considered a critique showing how creatures (intelligent horses in this case) that agree too much lose their “humanity.”
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VIII. How Few Meta-Rationals?
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he chooses his beliefs to be as close as possible to the truth.
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put substantial weight on other goals
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he understands the basic theory of disagreement,
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The theory of disagreement says that meta-rational people will not knowingly have self-favoring disagreements among themselves.
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Our working hypothesis for explaining the ubiquity of persistent disagreement is that people are not usually meta-rational.
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people do not 24 typically seek only truth in their beliefs,
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People tend to be hypocritical
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How many meta-rational people can there be?
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If meta-rational people were common, and able to distinguish one another, then we should see many pairs of people who have almost no dishonest disagreements with each other. In reality, however, it seems very hard to find any pair of people who, if put in contact, could not identify many persistent disagreements.
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Yet it seems that meta-rational people should be discernable via their conversation style.
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We know that, on a topic where self-favoring opinions would be relevant, the sequence of alternating opinions between a pair of people who are mutually aware of both being meta-rational must follow a random walk. And we know that the opinion sequence between typical non-meta-rational humans is nothing of the sort. If, when responding to the opinions of someone else of uncertain type, a meta-rational person acts differently from an ordinary non-meta-rational person, then two meta-rational people should be able to discern one another via a long enough conversation. And once they discern one another, two meta-rational people should no longer have dishonest disagreements.
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it seems that the fraction of people who are meta-rational must be very small.
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only a tiny non-descript percentage of the population, or of academics, can be meta-rational.
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we each seem to have little grounds for confidence in our own meta-rationality,
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IX. Personal Policy Implications
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Let us assume, however, that you, the reader, are trying to be one of those rare meta-rational souls in the world,
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never assume that you are more meta-rational than anyone else.
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Alternatively, you could adopt a "middle" opinion.
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we would want to construct a model of the process of individual self-deception,
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and infer where lies the weight of evidence,
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psychologists have found numerous correlates of self-deception. Self-deception is harder regarding one’s overt behaviors, there is less self-deception in a galvanic skin response (as used in lie detector tests) than in speech, the right brain hemisphere tends to be more honest, evaluations of actions are less honest after those actions are chosen than before (Trivers 2000), self-deceivers have more self-esteem and less psychopathology, especially less depression (Paulhus 1986), and older children are better than younger ones at hiding their self-deception from others (Feldman & Custrini 1988). Each correlate implies a corresponding sign of self-deception. Other commonly suggested signs of self-deception include idiocy, self-interest, emotional arousal, informality of analysis, an inability
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recognizing the difficulty of this problem can at least make us a bit more wary of our own judgments when we disagree.
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X. Conclusion
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We have therefore hypothesized that most disagreement is due to most people not being meta-rational, i.e., honest truth-seekers who understand disagreement theory and abide by the rationality standards that most people uphold. We have suggested that this is at root due to people fundamentally not being truth-seeking. This in turn suggests that most disagreement is dishonest.