Axiom talk:Axiom of Unions

At the risk of interfering mid-way, I wonder why we now have two pages for Axiom of Unions, for set theory and class theory, which do in fact state exactly the same thing (if you unpack the definition of union of set of sets). Am I missing something? &mdash; Lord_Farin (talk) 06:31, 9 May 2022 (UTC)


 * Subtle but important difference.
 * Axiom:Axiom of Unions/Set Theory allows you to create a union out of a set of sets.
 * Axiom:Axiom of Unions/Class Theory starts from having previously defined a union of a given class. Having done that, it then declares that if the class you built the union from was a set, then the union is also a set.
 * --prime mover (talk) 16:00, 9 May 2022 (UTC)


 * Got it, makes sense. Might be worthwhile to explicate this on the page, though, to avoid future confusion. &mdash; Lord_Farin (talk) 16:06, 9 May 2022 (UTC)