EDIT:
HatRack said:
Incorrect. I did not declare {} to be an existent set in step 1,
You don't have to declare anything in order to determine the existence of {}.
The existence of {} is determined right at the definition, even if one not explicitly declares it. All we need is elementary reasoning as follows:
Definition 1: {} is the set such that if the set X exists then X is not its member.
According to Definition 1, X must be any
existing set, including {}, otherwise set X can't be "not a member" of {}.
So right at the level of definition 1 {} is used to define its own property by not being one of the members, which is a circular reasoning, because {} is defined by using {} as a part of its own definition.
So, axiom 2 is already based on an existing object that is defined by circular reasoning, and therefore axiom 2 and conclusion 3 do not hold.
HatRack said:
It's definitely possible to state this axiom without using a definition at all, as I have done in previous posts informally and jsfisher has done formally.
HatRack said:
The Axiom of the Empty Set
There exists a set X such that if Y is a set then Y is not a member of X.
Let X in the previous step be known as the empty set, denoted by {}.
HatRack, if Y is a set, then Y is also X because X is also a set.
In that case X establishes a property of X by using X as one of the elements that establish a property of X, by not being a member of X, which is a circular reasoning.
Furthermore, you did not avoid the definition of {}, because this definition is an inseparable part of the axiom, as follows:
By using your of words
The Axiom of the Empty Set is:
"There exists a set X
such that if Y is a set then Y is not a member of X" where the blue part is actually Definition 1.
There is no previews step here, because the axiom is
not less than all of its parts at once, exactly as expressed by:
[latex]$$$\exists x\, \forall y\, \lnot (y \in x)$$$[/latex]