I've started reading a book on Intuitionist Type Theory, by J.G. Granstrom. More than half of it goes over my head but some remarkable ideas occasionally get stuck between the ears. For example, when he makes a definition of a set, he states that an element can be defined "in any way whatever, but always without reference to the totality of sets."
On the one hand, I understand that this technical limitation addresses the Russell's Paradox. On the other hand, it says loud and clear that we even theoretically can't handle the totality of all sets. Moreover, we should not even make an assumption that we might know the totality.
Another interesting statement from the book is that the Law of Excluded Middle is a not a matter of logic, but rather of existence. Therefore, if a proposition is true, it does not logically follow that its negation is false, and vice versa.
upd: due to the logical limitations described above, assumptions like this one "Пусть совокупность всевозможных состояний вселенной описывается набором параметров V1,V2 .... VN" look highly suspicious. If we can't handle the totality of all sets, we can't describe all possible states of the world in a logically consistent way.
On the one hand, I understand that this technical limitation addresses the Russell's Paradox. On the other hand, it says loud and clear that we even theoretically can't handle the totality of all sets. Moreover, we should not even make an assumption that we might know the totality.
Another interesting statement from the book is that the Law of Excluded Middle is a not a matter of logic, but rather of existence. Therefore, if a proposition is true, it does not logically follow that its negation is false, and vice versa.
upd: due to the logical limitations described above, assumptions like this one "Пусть совокупность всевозможных состояний вселенной описывается набором параметров V1,V2 .... VN" look highly suspicious. If we can't handle the totality of all sets, we can't describe all possible states of the world in a logically consistent way.