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