# More trouble for regular probabilitites

**Abstract**

In standard probability theory, probability zero is not the same as impossibility. But many have suggested that only impossible events should have probability zero. This can be arranged if we allow infinitesimal probabilities, but infinitesimals do not solve all of the problems. We will see that regular probabilities are not invariant over rigid transformations, even for simple, bounded, countable, constructive, and disjoint sets. Hence, regular chances cannot be determined by space-time invariant physical laws, and regular credences cannot satisfy seemingly reasonable symmetry principles. Moreover, the examples here are immune to the objections against Williamson’s infinite coin flips.

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References found in this work BETA

A Subjectivist’s Guide to Objective Chance.Lewis, David K.

Probability and the Art of Judgment.Jeffrey, Richard

How Probable is an Infinite Sequence of Heads?Williamson, Timothy

Set Size and the Part–Whole Principle.Parker, Matthew W.

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2013-03-13

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