Seems logical to me.
All: Are all numbers inarrgreater than zero (meaning there is no number not greater than zero) =>trueAny: Is there any number inarrthat is greater than zero =>false
But more important, according to Boolean Algebra:
arr.All(n => n > 0);
gives true, because it should be the logical opposite of
arr.Any(n => !(n > 0));
which gives false (actually this is what the above two points say).