Charity, population dynamics and the limits of rationality.

1. Charity, population dynamics and the limits of rationality. Lunch talk, IAS HUJI December 2006

2. Good people Drive: Good will. Tools: Moral education Utopia: no need for police and law enforcement. Equality. Community. Moto: From each according to his ability, to each according to his needs (Marx, Critique of the Gotha Program) Never worked. Rational agents Drive: Egocentricity. Tools: Training, stick and carrot policy. (tit for tat) Utopia: Capital growth. Excellence Individuals. Moto: everybody has a share (Milo Minderbinder, catch 22). Well… at least is doing better. Charity vs. “Game theory”: agents character and social order

3. R. Jehudah, R. Jose, and R. Simeon were sitting and Jehudah, the son of proselytes, • sat before them. R. Jehudah opened the conversation, saying: "How beautiful are the • works of this nation (the Romans). They have established markets, they have built bridges, they have opened bathing-houses.“ • R. Jose said nothing, • but R. Simeon b. Johai said: "All these things they have instituted for their own sake. • Their markets are gathering-places for harlots; they have built baths for the purpose • of indulging themselves in their comforts; they have built bridges to collect tolls from • those who cross them." • Jehudah, the son of proselytes, went and reported this conversation, • and it came to the ears of the government… • (Babylonian Talmud, Shabat 33b). • Are we looking for prosperity, or for piety? • Also an intera-religion dilemma, where the mystical thought tend to give priority to the intentions and devotion, the “establishment” tends to prefer action, not devotion. Spiritually – authenticity oriented: Thought Speech Did (action) “normal” religious establishment Thought Speech Did (action) "במעגלי רשע? עלית הרבנות החברתית", נ.ש., נקודה 296 (דצמבר 06)

4. To what extent capitalism works? Thomas Malthus 1798: “An essay on the Principles of population”: Population growth is exponential (geometric series). Resources (food and other needs) grow only linearly. The ultimate result should be a catastrophe: famine, war or disease.

5. Malthus against the Poor laws “The poor laws of England tend to depress the general condition of the poor in two ways. Their first obvious tendency is to increase population without increasing the food for its support. A poor man may marry with little or no prospect of being able to support a family in independence. They may be said in some measure to create the poor which they maintain, and as the provisions of the country must in consequence of the increased population, be distributed to every man in smaller proportions, it is evident that the labor of those who are not supported by parish assistance will purchase a smaller quantity of provisions than before and consequently more of them must be driven to ask for support.”

6. Was Malthus right? (1) In fact, the population actually grow exponentially Not enough for the poor in UK…

7. Was Malthus right (2) • But the GDP grows even faster …

8. Was Malthus right (3) • And the per-capita GDP… • Are we catalyze the growth ? (“Das human capital…”)

10. So, is rational planning for the future possible? Is social engineering, based on rational predictions, desirable?Are there cases where it is better to be ignorant ?

11. Buridan’s Ass • Jean Buridan (1300-1358): an entirely rationaldonkey, placed exactly in the middle between two stacks of hay of equal size and quality, will starve to death since it cannot make any rational decision to start eating one rather than the other • Mathematically speaking, for any space-time continuous algorithm that should map a continuum (like all point [0,1]) to binary decision (say, 0 OR 1) and for any finite time T, there should still a finite region of nonzero measure that has not yet mapped into either 0 or 1. (think about stretching a rubber band between 2 points) Thus, if the decision making algorithm of the donkey is deterministic, it MUST allow for few starting point that leads to its starvation to death. • Being rational may be dangerous to your health !! • Relevant to ATD converters, desynchronized peripheral devices … • One may argue that this type of failure is not common in nature. However, there are other situations where the “stacks of hay” are hidden. E.g., when the wolf pops out from his cave at the evening to look for a prey, it may has no clue about where it should go.

12. The E-Coli case: small creature, no memory. • Two types of movement: swimming in straight lines and tumbling, determined by the flagellar rotation. • In the absence of external stimulus, swimming is followed by tumbling, and the new swimming direction is determined at RANDOM. The bacteria acts as a random walker. • Along the swimming, the bacteria measures the concentrations of attractants (usually food) and repellents (usually poisons). Thus it knows what is the GRADIENT: does life becomes better along this direction, or worse? • In the presence of a chemical gradient bacteria will chemotax, or direct their overall motion based on the gradient. If the bacterium senses that it is moving in the correct direction (toward attractant/away from repellent), it will keep swimming in a straight line for longer before tumbling. If it is moving in the wrong direction, it will tumble sooner and try a new direction at random. • There is still a random component, even in the presence of gradient !!!!

13. Noise vs. deterministic action • Noise may help: to avoid deadlocks (Buridan), to avoid being stuck in local maxima, to confuse predators (game theory). • Of course, too much noise is harmful as it leads to waste of time and energy without any purpose. Optimal noise level Benefit Noise

14. Conjecture ANY PHYSIOLOGICAL AND MOVEMENT ACTIVITY IS CHARACTERIZED BY SOME LEVEL OF NOISE, CLOSE TO THE OPTIMAL NOISE FOR THAT ACTIVITY. Rational: Life = the ability to extract the benefits from spatio-temporal fluctuations. If evolution works, this ability has to improve with time, including not only the deterministic parts (detaction, memory) but also noise optimization (?). Some support from HRV data, but …

15. Bon Appetite !