Re: poly: What probabilities?

From: Nick Bostrom <>
Date: Sun Apr 26 1998 - 17:42:28 PDT

Peter C. McCluskey wrote:

> >"Here's a scenario which I would guess has a 0.1 to 10% chance of
> > happening: 1) a self-replicating molecular assembler becomes able to
> > manufacture...",

> Can you produce 2 reasonable interpretations of my statement which
> have nontrivially different implications?

Interpretation 1: You say something about the objective probability
of the scenario in question, i.e. that if we prepared a large number
of systems in states indistinguishable from the present state of
civilization here on earth (modulo our knowledge thereof) then the
fraction of them which would develop in accordance with the scenario
is between 0.1 and 10%.

Interpretation 2: You say that relative to what you know, you assign
a subjective probability somewhere between 0.1 and 10%.

These two interpretations are substantially different. For
example, if one thinks that the scenario you describe will eventually
lead to successful space colonization, then if (1) is right the Great
Filter cannot be in our future, whereas if (2) is right that is still
possible. In other words, interpretation 1 implies that if there are
millions of civilizations reaching our present degree of
development, then some of them will almost certainly follow the
scenario you describe; but interpretation 2 doesn't imply that.

Nick Bostrom
Department of Philosophy, Logic and Scientific Method
London School of Economics
Received on Sun Apr 26 23:48:21 1998

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