20.0. Buridan’s ass and the psychological origins of objective probability

The medieval philosopher Buridan reportedly constructed a thought experiment to support his view that human behavior is determined rather than “free”—hence rational agents can't choose between two equally good alternatives. In the Buridan’s Ass Paradox, an ass finds itself between two equal equidistant bales of hay, noticed simultaneously; the bales’ distance and size are the only variables influencing the ass’s behavior. Under these idealized conditions, the ass must starve, its predicament indistinguishable from a physical object suspended between opposite forces, such as a planet that neither falls into the sun nor escapes into outer space. (Since the ass served Buridan as metaphor for the human agent, in what follows I speak of “ass” and “agent” interchangeably.)

Computer scientist Leslie Lamport formalized the paradox as “Buridan’s Principle,” which states that the ass will starve if it is situated in a range of possibilities that include midpoints where two opposing forces are equal and it must choose in a sufficiently short time span. We assume, based on a principle of physical continuity, that the larger the bale of hay compared to the other, the faster will the ass be able to decide. Since this is true on the left and on the right, at the midpoint, where the bales are equal, symmetry requires an infinite decision time.  Conclusion: within some range of bale comparisons, the ass will require decision time greater than a given bounded time interval. (For rigorous treatment, see Buridan’s Principle (1984).)

Buridan’s Principle is counterintuitive, as Lamport discovered when he first tried to publish. Among the objections to Buridan’s Principle summarized by Lamport, the main objection provides an insight about the source of the mind-projection fallacy, which treats probability as a feature of the world. The most common objection is that when the agent can’t decide it may use a default metarule. Lamport points out this substitutes another decision subject to the same limits: the agent must decide that it can’t decide. My point differs from that of Lamport, who proves that binary decisions in the face of continuous inputs are unavoidable and that with minimal assumptions they preclude deciding in bounded time; whereas I draw a stronger conclusion: no decision is substitutable when you adhere strictly to the problem’s conditions specifying that the agent be equally balanced between the options. Any inclination to substitute a different decision is a bias toward making the decision that the substitute decision entails. In the simplest variant, the ass may use the rule: turn left when you can’t decide, potentially entrapping it in the limbo between deciding whether it can’t decide. If the ass has a metarule resolving conflicts to favor the left, it has an extraneous bias.

Lamport’s analysis discerns a kind of physical law; mine elucidates the origins of the mind-projection fallacy. What’s psychologically telling is that the most common metarule is to decide at random. But if by random we mean only apparently random, the strategy still doesn’t free the ass from its straightjacket. If it flips a coin, an agent is, in fact, biased toward whatever the coin will dictate, bias, here, means an inclination to use means causally connected with a certain outcome, but the coin flip’s apparent randomness is due to our ignorance of microconditions; truly random responding would allow the agent to circumvent the paradox’s conditions. The theory that the agent might use a random strategy expresses the intuition that the agent could turn either way. It seems a route to where the opposites of functioning according to physical law and acting “freely” in perceived self-interest are reconciled.

This false reconciliation comes through confusing two kinds of symmetry: the epistemic symmetry of “chance” events and the dynamic symmetry in the Buridan’s ass paradox. If you flip a coin, the symmetry of the coin (along with your lack of control over the flip) is what makes your reasons for preferring heads and tails equivalent, justifying assigning each the same probability. We encounter another symmetry with Buridan’s ass, where we also have the same reason to think the ass will turn in either direction. Since the intuition of “free will” precludes impossible decisions, we construe our epistemic uncertainty as describing a decision that’s possible but inherently uncertain.

When we conceive of the ass as a purely physical process  subject to two opposite forces (which, of course, it is), then it’s obvious that the ass can be “stuck.” What miscues intuition is that the ass need not be confined to one decision rule. But if by hypothesis it is confined to one rule, the rule may preclude decision. This hypothetical is made relevant by the necessity of there being some ultimate decision rule.

The intuitive physics of an agent that can’t get stuck entails: a) two equal forces act on an object producing an equilibrium; b) without breaking the equilibrium, an additional natural law is added specifying that the ass will turn. Rather than conclude this is impossible, intuition “resolves” the contradiction through conceiving that the ass will go in each direction half the time: the probability of either course is deemed .5. Confusion of kinds of symmetry, fueled by the intuition of free will, makes Buridan’s Principle counter-intuitive and objective probabilities intuitive.

How do we know that reality can’t be like this intuitive physics? We know because realizing a and b would mean that the physical forces involved don’t vary continuously. It would make an exception, a kind of singularity, of the midpoint.  

14.2.1. The habit theory of morality, moral influence, and moral evolution

Contrasting with all forms of moral realism, the habit theory of morality recognizes no “terminal moral values,” since it holds that transgression of an agent’s principles of integrity is necessary to allow their adjustment to circumstances. By conceiving moral principles as principles of integrity, prosocial habits serving as indispensable self-control devices in a psychological economy where willpower is an exceedingly scarce resource, it uniquely explains—without recourse to group selectionism—how humans could evolve a group-minded morality.

Group selectionism is the minority view among evolutionists that natural selection in humans occurs in the manner of eusocial species, at the level of groups, not just genes. Eusocial species comprise primarily the social insects, whose hives’ genetic commonality permits group selection, which in their case—unlike the human—reduces to the gene level. Social psychologist Jonathan Haidt in his recent book The Righteous Mind (2013) frames the case for human group selection with the aphorism “Humans are 90% chimpanzee and 10% bee.” Haidt observes that most moral arguments are hypocritical, aiming to impress or control others, agents often ignoring standards when they can avoid punishment for transgressions. Yet Haidt acknowledges that humans occasionally behave selflessly, as when a soldier takes huge personal risks for his fellows or zealots lose themselves in moral or political causes. Haidt thinks these phenomena inexplicable at the gene or individual level because it would subject agents to strongly adverse selection pressures, since their altruism fails to serve their individual interests. Group selectionism is subject to a standard objection: inevitable exploitation by free riding, which group-selectionist theory must contain a mechanism to punish. Human societies curtail free riding by social approval and disapproval, including material rewards and punishments.

According to Haidt (and other strict-adaptationist theorists), the proclivity to reward and punish transgression against group interest must arise through group selection because otherwise approval and disapproval meted out in the group interest would be another form of self-sacrifice. The habit theory of morality treats moral approval and disapproval as expressing the same habit set used for self-control, illustrated by the habit theory of civic morality: U.S. citizens practice habits of frugality in their personal lives by demanding the government cut spending. The same equivalence describes moral suasion directed toward individuals.

Ironically, moral hypocrisy provides evidence that self-control and moral suasion practice a unified moral habit. If hypocritical demands are seen as purely deceptive, it’s hard to see how they would serve as a costly signal; carrying no costs, moral hypocrisy would have no value as a signal. Hypocrisy has no point if anyone can be a hypocrite cheaply. But if engaging in moral suasion agents rehearse (practice) principles of integrity that they habitually apply to themselves, the cost of demanding more morality than you want to give is becoming more moral than you wish.

The workings become clearer and more plausible with more concreteness about the structure of the moral habits (or principles of integrity), and Alan P. Fiske’s relationship-regulation theory integrates well with the habit theory. According to Fiske’s model, systems of moral principles are activated when their associated social relationships are “constituted,” where the systems of moral principles are Unity, Hierarchy, Equality, and Proportionality. (T.S. Rai and A.P. Fiske, Moral psychology is relationship regulation (2011) Psychological Review, 118: 57 ‒ 75.) Hierarchical principles, for example, are activated when the appropriate social relations of Authority/Ranking are constituted, so when an agent is involved in an authoritarian relationship, such as between employees and their boss, the corresponding Hierarchical principles of unconditional submission and conditional protection dominate. To restate in habit-theory terms, negotiating hierarchical relationships motivates agents to form habits based on Hierarchical principles. Most importantly, the Hierarchical structure is a coherent whole, including facets involving regulation of both self and others. In the habit theory, other-directed morality is a spandrel deriving from the primary adaptive value of self-control.