  Epicurus himself had appealed to what is evident to provide positive ‘attestation’ (epimarturêsis) of true beliefs about perceptibles ‘hereabouts’, and ‘contestation’ (antimarturêsis) of false beliefs about theoretical items such as atoms, and about extremely distant perceptible objects; always provided it is explanatorily adequate, lack of evidence of any kind against a theoretical belief is sufficient grounds for taking it to be true, (Ep. Herodot. 80, Ep. Pythocles 86–88; each such belief will constitute a true explanation of this type of phenomenon in one or other of the infinite number of world-systems in the universe). In On Signs, in contrast, what phenomena ‘conflict’ (antipiptein, makhesthai) with, if they do, are empirical generalizations, which are thereby falsified (e.g., §1, xvii 28–xviii 16). Thus while Epicurus argues that the non-existence of void is contested by the phenomenon of movement, these Epicureans argue that nothing evident contests the local generalization that moving things hereabouts all move through empty spaces.