among the atoms ionized by the particles; see [Mott]{} [@Mot]. No such analysis seems to be available, however, that would explain why we see macroscopic bound states (such as you or me) move along fairly definite paths.

The traditional context for discussing the inconsistency of definite particle paths is the double slit experiment ([Bohr]{} [@Boh]), where it is claimed that electrons (or photons) passing a diaphragm containing the two slits cannot be said to have passed through one or the other slit, or – even worse – are said to have passed through both, in a way (superposition) that defies intuition.

Unfortunately, the discussion seems always to be connected to measurement questions, so that it is difficult to discern the mathematical content of the arguments that claim [*nonexistence*]{} of the path (in contrast to its [*limited measurability*]{} only, [Wootters & Zurek]{} [@WooZ]). However, I gathered some indirect evidence about particle paths by reading between the lines of some papers.

[Feynman]{} [@Fey], in laying ground work for his (nonrelativistic) path integral formalism, discusses on p. 371 the probability of particle paths as his first postulate:

[*If an ideal measurement is performed to determine whether a particle has a path lying in 