This is a reply to Eric Hawthorne and Tim May.

Eric Hawthorne wrote:

>George Levy wrote:

All this involves really basic probability theory.
The first person perspective probability is identical to the probability conditional to the person staying alive.

>But that first-person probability is not objective,

true. It is a first person point of view.

>and not valid, and not useful.

not true as the example demonstrates
>Consider this from a purely pragmatic point of view. (Not a formal argument per say.)
>A person must consider the (non-zero) objective probability that they will die (and be then non-existent) (if they >do this or that action). If people did not account for the probability
>that they will die if they do a foolish act, then they will probably die. Their subjective
>1st person sense of probability is naively optimistic and not a survival trait. If
>a person acts with that kind of probability belief in every possible world, they will
>reduce their measure beyond measure. Surely there is something incorrect about
>a probability view which has that detrimental effect on one's measure.

Reread the example. The way the example is set up, the probability of Alice's survival is not affected one iota by her investment. It remains constant with a value of 20% whether she buys the stock or not. The issue the example intends to illustrate is her decision with regard her return on investment.

Of course one could construct another example where her survival is decreased (as in conventional QS) or increased (Alice's investment has an impact on Charles' research and makes Charles' success more probable). But that is another story.

As I mentioned earlier, if measure is infinite, there may not be any sense in talking about increasing or decreasing absolute  measure.

If absolute measure did have meaning, one's measure should keep decreasing as one ages since the cumulative probability of one's dying increases with age. Yet from a subjective viewpoint an old man and a young man have the same measure.

A concept that I discussed a few months ago, was the extension of the Cosmological Principle to the manyworld. The Cosmological Principle asserts that the universe is uniform in the large scale, independently of where the observer is positioned. An extension of this principle that supported the Steady State theory asserted that the universe looked the same at any time in its history. This extension has been discredited by the evidence for an expanding universe. However, one could argue that the reason the Cosmological Principle does not work is that the scope of its application is not large enough. With the Manyworld (or in the limit, the Plenitude) we are bound to have the largest possible scope possible, and therefore the Cosmological Principle should work. The Cosmological Principle is also appealing in that it describes the Manyworld with the smallest amount of information possible.

Thus the Cosmological Principle applied to the Manyworld states that measure is independent of the position of the
observer. If the Cosmological Principle holds then we should not have to worry about absolute measure.

Tim May wrote:

On Thursday, January 9, 2003, at 08:22  PM, George Levy wrote:
OK. Let's consider the case of the guy dying of cancer and playing the stock market simultaneously.. In real life, the hard part is to get meaningful probability data. For the sake of the argument let's assume the following scenario:

..scenario elided, not to mislead, but because I will not be using any details of the calculation...

As we can see, the rate of return for Alice is 4.8 times that of Bob. Alice will make a profit, but not Bob.

All this involves really basic probability theory.
The first person perspective probability is identical to the probability conditional to the person staying alive.
The probability of the event in question (stock going up) must be tied to the person staying alive ( a cure for cancer). In the case of a "conventional" QS suicide to world conditions matching the requested state: ie. winning one million dollars. In the deathrow case one could imagine a scenario in which the event in question (DNA test discovery) is tied to a reprieve from the governor coming because of a DNA test exhonerating the prisoner. The prisoner could bet on DNA testing as a good investment.  The airline case is similar. The hard part is figuring the probability of very unlikely saving events such as a scientific discovery,  ET landing on earth or the coming of the messiah :-)

How is this different from standard life insurance arguments, where buying a policy is betting one will die and not buying a policy is betting one will live? If one has no heirs to worry about, no concern about the world if and after one dies, then it has been known for a long time that the "smart" thing to do is not to buy life insurance. If one dies, the policy payoff is worthless (to the dead person), but if one lives, the money has been saved.

Similar calculations are very simple for going into a dangerous situation: take a bet, at nearly any odds, that one will live. If the odds of survival in going into a combat situation are one in a hundred, and betting odds reflect this, bet everything one can on survival. If one dies, the $10,000 lost is immaterial. If one lives, one has a payout of roughly a million dollars.

OK. I agree with you, Tim. Taking a life insurance is the reverse strategy of QS (impoverishing yourself in your world so that your family will be enriched in the other worlds).

Lastly, like most "many worlds" views, the same calculations apply whether one thinks in terms of "actual" other worlds or just as possible worlds in the standard probability way (having nothing to do with quantum mechanics per se).
Good point.

Or so I believe. I would be interested in any arguments that the quantum view of possible worlds gives any different measures of probability than non-quantum views give. (If there is no movement between such worlds, the quantum possible worlds are identical to the possible worlds of Aristotle, Leibniz, Borges, C.I. Lewis, David Lewis, Stalnaker, Kripke, and others.)

Interesting. I don't know how to proceed in this area.


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