Friday, August 12, 2011

(Even) God is a Satisficer

To 'satisfice' means "To decide on and pursue a course of action that will satisfy the minimum requirements necessary to achieve a particular goal." (Oxford English Dictionary). Herbert Simon (1978 Nobel Prize in Economics) was the first to use the term in this technical sense, which is an old alteration of the ordinary English word "satisfy". Simon wrote (Psychological Review, 63(2), 129-138 (1956)) "Evidently, organisms adapt well enough to 'satisfice'; they do not, in general, 'optimize'." Agents satisfice, according to Simon, due to limitation of their information, understanding, and cognitive or computational ability. These limitations, which Simon called "bounded rationality", force agents to look for solutions which are good enough, though not necessarily optimal. The optimum may exist but it cannot be known by the resource- and information-limited agent.

There is a deep psychological motivation for satisficing, as Barry Schwartz discusses in Paradox of Choice: Why More Is Less. "When people have no choice, life is almost unbearable." But as the number and variety of choices grows, the challenge of deciding "no longer liberates, but debilitates. It might even be said to tyrannize." (p.2) "It is maximizers who suffer most in a culture that provides too many choices" (p.225) because their expectations cannot be met, they regret missed opportunities, worry about social comparison, and so on. Maximizers may acquire or achieve more than satisficers, but satisficers will tend to be happier.

Psychology is not the only realm in which satisficing finds its roots. Satisficing - as a decision strategy - has systemic or structural advantages that suggest its prevalence even in situations where the complexity of the human psyche is irrelevant. We will discuss an example from the behavior of animals.

Several years ago an ecological colleague of mine at the Technion, Prof. Yohay Carmel, posed the following question: Why do foraging animals move from one feeding site to another later than would seem to be suggested by strategies aimed at maximizing caloric intake? Of course, animals have many goals in addition to foraging. They must keep warm (or cool), evade predators, rest, reproduce, and so on. Many mathematical models of foraging by animals attempt to predict "patch residence times" (PRTs): how long the animal stays at one feeding patch before moving to the next one. A common conclusion is that patch residence times are under-predicted when the model assumes that the animal tries to maximize caloric intake. Models do exist which "patch up" the PRT paradox, but the quandary still exists.

Yohay and I wrote a paper in which we explored a satisficing - rather than maximizing - model for patch residence time. Here's the idea. The animal needs a critical amount of energy to survive until the next foraging session. More food might be nice, but it's not necessary for survival. The animal's foraging strategy must maximize the confidence in achieving the critical caloric intake. So maximization is taking place, but not maximization of the substantive "good" (calories) but rather maximization of the confidence (or reliability, or likelihood, but these are more technical terms) of meeting the survival requirement. We developed a very simple foraging model based on info-gap theory. The model predicts that PRTs for a large number of species - including invertebrates, birds and mammals - tended to be longer (and thus more realistic) than predicted by energy-maximizing models.

This conclusion - that satisficing predicts observed foraging times better than maximizing - is tentative and preliminary (like most scientific conclusions). Nonetheless, it seems to hold a grain of truth, and it suggests an interesting idea. Consider the following syllogism.

1. Evolution selects those traits that enhance the chance of survival.

2. Animals seem to have evolved strategies for foraging which satisfice (rather than maximize) the energy intake.

3. Hence satisficing seems to be competitively advantageous. Satisficing seems to be a better bet than maximizing.

Unlike my psychologist colleague Barry Schwartz, we are not talking about happiness or emotional satisfaction. We're talking about survival of dung flies or blue jays. It seems that aiming to do good enough, but not necessarily the best possible, is the way the world is made.

And this brings me to the suggestion that (even) God is a satisficer. The word "good" appears quite early in the Bible: in the 4th verse of the 1st chapter of Genesis, the very first book: "And God saw the light [that had just been created] that it was good...". At this point, when the world is just emerging out of tohu v'vohu (chaos), we should probably understand the word "good" as a binary category, as distinct from "bad" or "chaos". The meaning of "good" is subsequently refined through examples in the coming verses. God creates dry land and oceans and sees that it is good (1:10). Grass and fruit trees are seen to be good (1:12). The sun and moon are good (1:16-18). Swarming sea creatures, birds, and beasts are good (1:20-21, 25).

And now comes a real innovation. God reviews the entire creation and sees that it is very good (1:31). It turns out that goodness comes in degrees; it's not simply binary: good or bad. "Good" requires judgment; ethics is born. But what particularly interests me here is that God's handiwork isn't excellent. Shouldn't we expect the very best? I'll leave this question to the theologians, but it seems to me that God is a satisficer.

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