David Joyce
Professor of Mathematics and Computer Science at Clark University
Science replaces vague terms by precise ones. This has been going on
since the Greek mathematicians formalized geometry about the same time
as Eubulides proposed the sorties paradox.
Eubulides’ paradox argued that a single grain of sand isn’t a heap and
adding a single grain won’t change a nonheap into a heap, yet there are
heaps of sand.
One can simply say that a single grain of sand by itself is a one-grain
heap of sand, and the paradox goes away. Alternatively, you could define
a single grain of sand as a nonheap, but define two grains of sand as a
two-grain heap.
Which definition, whether it be one of the two above or some other
definition, depends on the application in mind and the elegance of the
resulting language. If you’re investigating how heaps of sand collapse,
you might require at least two sand grains with one atop another, since
one by itself can’t collapse. On the other hand, if you’re thinking of a
heap of sand being much the same as a set of sand grains, you might
require only one. That could make a more elegant theory: given a pile of
sand, if you remove one grain of sand at a time, it remains a pile of
sand until there is no sand left.
There are other solutions to this question that are more complicated.
You could change your logic. Deny the law of the excluded middle. Use
fuzzy logic. Or you could keep to classical logic but make “heapiness” a
function with a numerical value rather than a predicate.
https://www.quora.com/If-you-keep-removing-a-grain-of-sand-from-a-pile-till-what-point-does-it-remain-a-pile
(I did not do well in my Computational Logic in my younger days.)