Mattara said:
No, you can't make that assumption, since T contains more than 1 (and more than 2) elements, or are you suggesting that there only exists one true proposition?
eh, no...of course there is more than one true proposition

that was merely a simple example I used to illustrate the difference between 2 concepts that you are confusing to be identical or similar- it was just an (unsuccessful it seems) attempt to show you how you unjustifiably transfer properties from one set to another.
Mattara said:
T is the set of all true propositions.
U is the power set of T, which means it contains the exact same elements as T, plus an additional large amount of elements that are the subsets of T (it contains more copies of the elements in T.
this is partially correct and wrong in the rest.
P(T) is a set that contains sets of "elements", it is a family of sets. T on the other hand, contains true propositions... that P(T) has a greater cardinality than T is indeed correct, but P(T) contains no additional true propositions that are not in T: all elements of P(T) -with the exception of the empty set- are formed as sets of true propositions
from T.
also, that P(T) contains more "copies" of the same true proposition is true, but indeed has no relevance whatsoever to the frame of your (incorrect) argument.
Mattara said:
However, from assuming omniscience, T was defined as the set of all true propositions, which has to be larger than T.
T={p| p is true} until here, I agree but... what do you mean by T has to be larger than T?
Mattara said:
Thus T has contradictory properties and cannot exist, and therefore omniscience cannot exist.
that's very nice except T has no contradictory properties. :)
Mattara said:
I don't know why this is so hard to grasp.
oh, ironically: that's exactly what I was thinking...
Mattara said:
(1) Do you agree that I have defined T as the set of all true propositions?
of course... I agreed with this part since my first post.
Mattara said:
(2) Do you agree that a power set of T contains more elements than T?
why certainly. the power set of a set has a strictly higher cardinality than the set. this is a known mathematical fact.
Mattara said:
(3) Do you agree that there can be no larger set of true propositions than the set of all true propositions, since a conjunction of two true propositions is also true?
yes. that there is no "larger" set of true propositions, than the set of all true propositions: that's an a priori truth.
Mattara said:
Since both (2) and (3) becomes true if you assume omniscience and 2 AND 3 is a contradiction, the assumption of omniscience is invalid.
2 and 3 are not contradictory!
you fail to understand the notions of power set, and cardinality.
that the power set of T has a higher cardinality than T in no way implies that P(T) contains truths that the set of all truths does not (what it is that you're claiming, and what you state the contradiction to be).
Again, I will type a tiny, trivial example to exemplify this (so we won't go into lengthier text, I'll use a small finite set).
Let S be a an arbitrary finite set: S={x,y},
it's power set is then P(S)={{ },{x},{y},{x, y}}
Evidently, P(S) has no element F where F={z| z ∉ S}.
And this holds for any set (finite or infinite), and it is an a priori truth (from the very definition of the power set) that there is no F ∈ P(S) such that F={z| z ∉ S}, since all the elements of P(S) are defined as
subsets of S.
...