Over at FRDB we recently discussed whether propositions are objective (i.e. exist independent of any mind). Usually, I prefer to take a nominalist approach, but in this thread I decided to assume the role of a platonist.
Physicalist, a nominalist, wrote that:
[…] the proposition “the universe exists” did not exist before there were conscious agents.1
I attempted to argue that this was wrong. Here’s my argument:
D:x ≡ things
Px ≡ x is a proposition
Tx ≡ x is true
Wx ≡ x was true
Bx ≡ x was true before there were any conscious agents
Ex ≡ x existed before there were conscious agents
1. There is at least one x such that x was a true before there were conscious agents.
(∃x)(Bx)
2. For all x, if x was true before there were conscious beings, then x was true and x existed before there were conscious agents.
(∀x)(Bx→Wx∧Ex)
3. Therefore, There is at least one x such that x was true before there were conscious beings, then x was true and x existed before there were conscious agents. (From 1, 2)
⊢ (∃x)(Wx∧Ex)
4. For all x, if x was true, then x is a proposition. (Premise)
(∀x)(Wx→Px)
5. Therefore, There is at least one x such that x was true and x existed before there were conscious agents and x is a proposition. (3, 4)
⊢ (∃x)(Wx∧Ex∧Px)
(5) is incompatible with the view that propositions are mind-dependent.2
But I think LukeS nailed the equivocation on which the argument “rested” when he wrote:
No, possible strawman, I think he said there were facts (things), not truths (statement fact relations). So it would be proper to say “it was a fact that…” but not “it was true that…”.
Using technical definitions talk of facts and truths is not equivalent.3
So, so far, no platonism (relative to the problem of universals) for me.
1http://www.freeratio.org/showthread.php?p=5848257#post5848257
2http://www.freeratio.org/showthread.php?p=5848354#post5848354
3http://www.freeratio.org/showthread.php?p=5848365#post5848365