Sure.
But if all I intend to do is define that which ultimately resulted in my pizza being on my plate as "delivered by Bob" then I am simply playing with words and adding nothing new to one's knowledge other than a definition.
And any attempt at evidence to the reality of "delivered by Bob" is simply circular.
Yes. (And, good example, by the way!) Although I'm essentially repeating your point, I'd like to expand just a little.
Compare:
1. Bob delivers pizza to my table IMPLIES there is pizza on my table. Or: IF Bob delivers pizza to my table THEN there is pizza on my table.
and
2. Bob delivers pizza to my table IS EQUIVALENT TO there is pizza on my table. Or: Bob delivers pizza to my table IF AND ONLY IF there is pizza on my table.
Case 1 is deductive logic. If Bob has delivered the pizza, then I can conclude I have pizza. But don't be tempted to reverse this! If I have a pizza, it does
not necessarily follow that Bob delivered it. After all, Alice also delivers pizzas. If you attempt to deduce from the pizza the fact of Bob, you're affirming the consequent, which is a logical fallacy.
In Case 2, we simply have two statements with the same logical content. Given (2), we could say that,
by definition, pizza and Bob's delivery go together. You can't have one without the other. But notice that
causation is essentially gone, now. If there's Bob, there's pizza; if there's pizza, there's Bob. Maybe Bob causes pizza. Maybe pizza causes Bob. Maybe it's better to just regard them as the same thing, since they always go together.
But then, are we just playing with words? If Bob is nothing
but pizza, and pizza is nothing
but Bob, then we just have two words for the same thing. You can't have one without the other.
Consider the argument that
everything is evidence of God. As before, the possibilities are:
1. IF God creates everything THEN everything exists.
2. God creates everything IF AND ONLY IF everything exists.
As before, (1) cannot be used to infer God from the existence of universe (everything). It can only go the other way: we can infer the universe if we have already established God. That is, if we try to use the universe as evidence of God, with the logical implication (1), we're making an error of logic by affirming the consequent.
On the other hand, if we go with (2), then we're essentially just renaming "the universe" with the label "God". God and the universe are indistinguishable if our argument is (2).
One obvious problem with (2), of course, is that religions typically make a distinction between God and the universe. That is, self-described theists do not identify God with "everything".
It is worth pointing out that both Musika and Jan Ardena have explicitly denied that God and "everything" are one and the same.
Musika has argued for God as the "enabler" of everything, which is more like argument (1) than argument (2). But then Musika cannot appeal to the existence of "everything", along with (1), to prove the existence of God. That would be a logical error.
Jan Ardena, on the other hand, has argued that "God is not a thing". "Everything" is the collection of all "things", and Jan has explicitly and repeatedly said that God stands apart from this collection. So, while Jan's argument often drifts around and looks a lot like (2), he isn't consistent in that position. Moreover, even if we
did have such consistency from Jan, (2) does nothing to establish God as the "supreme being" of Jan's religion. Jan appears at times to agree with (1). Maybe he has a similar position to Musika on that; it's hard to tell since Jan isn't very clear most of the time. But if that is the case, then he is in no better logical position than Musika to argue backwards from the universe to God.
But maybe I'm not being entirely fair to Jan. Jan's main assertion about God is "God Is". That is, God
just exists, by assertion, and Jan's done. This, of course, is not an
argument for God's existence. I think that because Jan's God exists only by assertion, this explains both why Jan cannot provide any evidence for his God, and also why he feels that it is unnecessary to do so. For Jan, God is an unquestionable premise that requires no proof. Thus, niceties like logic and rational argument are not necessary, for him.