Of course that’s reasonable. But I don’t like that it’s a quote, this Dr. has no authority on reality or reason, and isn’t here to be smacked around.
It’s like this for all concepts though, not just these specific axioms.
For instance, if I made up a fictional beast, let’s call it “Bigfoot”, and described it and it became an urban legend. If one day we found a creature in the woods that happened to match the description I invented, some may feel compelled to claim:
We have found bigfoot.
But that cannot be true, since the concept was not based on this newly discovered, existing creature. It may be a fitting name to give it, but the definition has now changed from “fictional concept”, to “that existing/observable hairy animal there.” That is a change in definition, the truth values didn’t change:
bigfoot(1) does not exist (cannot).
vs.
bigfoot(2) (this new hairy beast) does exist.
Easy to confuse, but also easy to see why they are not the same.
Likewise, the universe is so defined. If there are more dimensions, and we know of them, they are likewise “part of the universe”. If we limit the universe to mean dimensions XYZ and not ABC, then we need new definitions. Sub-univese vs universe, etc. The reasoning however, will not (cannot) change.
All of existence will necessarily include everything by definition (causes, dimensions, whatever). This sort of definition is conceptual, based on any and all future findings. There is a common definition for this type of statement, it eludes me at the moment, perhaps some others recall the classification of it. Basically it cannot be demonstrated to be true or false, it’s infinite in scope, and defined as “any future state”.
Please note, if the universe = the known univese AT THAT TIME, that it can be demonstrated to be false. as someone pointed out, if some “dimension” is unknown now, but is known later, and turns out to “contain” the “known universe”, and to have caused it’s existence, then the OP is false.
If universe = any future state (infinite), then yes sure, it cannot by definition, be false. That is, any known cause immediately becomes part of the set of “all that is”.
-Mach