Both similar-sign inferences (e.g., all humans are mortal because those hereabouts are mortal) and dissimilar-sign inferences (e.g., movement as a sign of void) are grounded in experiential assurance.
A way of reasoning where you conclude something is true about a whole group based on observing it in a smaller part of that group—like saying all humans are mortal because the people you know around you die.
grounded in(whether distinctness or identity is explained by intrinsic features)
To be explained by or to have its reason or basis in something else—like how a tree being wet is grounded in (explained by) recent rain.
void(Aristotle's definition, used as the basis for his argument against the existence of a void)
But the author of §4, at any rate, insists that it is only because we have observed that moving things hereabouts, despite other differences, all share the property of moving through empty spaces, that we affirm that the same thing holds without exception in non-evident places too (xxxv 36–xxxvi 7). The full form of this sign-inference would therefore run: “Since moving things hereabouts all move through empty space, all moving things move through empty spaces; and since all moving things move t