It has occured to me that in trying to define what "existence" is (as in "Existence exists"), I end up with a definition that's pretty much identical to that of the universe: everything that exists. The Ayn Rand lexicon quotes Leonard Peikoff defining the universe thus:
Unfortunately, there doesn't seem to be an equally succinct definition of existence. So, obviously, my question is, what is "existence" as distinguished from the universe?
And, on further thought, the lexicon also quotes Galt's speech:
How is that different?
I have a strong sense that these terms mean different perspectives on the same basic set of referents, but I can't quite put my finger on the distinction, so I'd appreciate it if someone could help me.
asked Dec 16 '11 at 13:34
While addressing a question of the relationship of 'existence' to 'existent' from the appendix of Introduction to Objectivist Epistemology(ITOE):
Existence and identity are an integration of the units which consist of 'every entity, attribute, action, event or phenomenon (including consciousness) that exists, has ever existed or will ever exist.' This too, comes is parsed from pg. 56 of ITOE.
Existence carries with it a certain way of regarding the universe as 'a state of being' or 'the fact of being'.
The universe can used to mean the entirety of existence, or the world of human experience, or sometimes just the elements relevant to a particular discussion or problem [Merriam-Webster]
Reality carries with it the state or quality of being real. In this sense reality is something that is neither derivative nor dependent but exists necessarily. [Merriam-Webster]
In the comments, the questioner also asks about the relation between the statement, "Existence exists," and the statement, "The universe exists." The excerpts on the topic of "Universe" in The Ayn Rand Lexicon do, indeed, seem to treat "universe" as more or less the same as "existence." This is an example of "universe" as that term is typically used in philosophy. What may be confusing is that physicists often tend to use "universe" more narrowly, referring specifically to the physical "world" or "universe," i.e., the presently understood physical universe, from a primarily physical perspective.
Philosophically, the statement, "The universe exists," may leave open the possibility that there may be "non-universe" things that also exist. If someone says, "The universe exists," that may create the impression that other things might exist, too, in addition to the universe. The redundancy of saying that the universe exists isn't as obvious as in the statement that existence exists. "To exist" is being used as the fundamental concept, so why not express the idea that there is an existence by saying that "existence exists" rather than confuse the issue by switching to "universe" instead of "existence"? We have to use the term "exist" anyway, so why confuse the issue by switching to "universe" when we could simply say "existence"? "Existence exists" focuses on existence per se, while "universe" focuses on the all-inclusiveness of "existence," which is a further development beyond existing at all.
Ayn Rand has commented that the most axiomatic statement about any axiomatic concept is in the form of a redundancy:
...one must remember the axiom: Existence exists. (This, incidentally, is a way of translating into the form of a proposition, and thus into the form of an axiom, the primary fact which is existence.) Please bear in mind the full statement: "Existence exists—and the act of grasping that statement implies two corollary axioms: that something exists which one perceives and that one exists possessing consciousness, consciousness being the faculty of perceiving that which exists." (Atlas Shrugged.) [Quoted from ITOE, Introduction.]The axiom form of "reality" would be "reality is real." In Galt's Speech, for example, Ayn Rand writes: "A savage is a being who has not grasped that A is A and that reality is real." The opposite of "real" would be "unreal" and would be capable of "existing" only in a consciousness, as some form of idea (in consciousness) that does not correspond to reality, i.e., to existence. In other words, "reality" expresses an element of "identity" that is only indirect and implicit in "existence." "Reality" highlights the identification that "existence is identity."
Update on "Universe"
For further insight on Ayn Rand's usage of the term "universe," refer to her article, "The Metaphysical Versus the Man-Made," reprinted as Chapter 3 in Philoosophy: Who Needs It. One excerpt from that article is included in the topic of "Universe" in The Ayn Rand Lexicon, along with the lead excerpt by Dr. Peikoff.