What makes a mental image an idea but a mental sound (else an imagined smell, taste, or tactile feel) not an idea? — javra
I don’t mean just visual images, but the all-sensory sense of “image” used in the very way you just said “IMAGined” smell etc.
Moreover, how can one obtain a correspondence to reality in the absence of some idea which so corresponds? — javra
Here you’re using “idea” in the same sense as I am. Figurative, you’ve got a drawing, which could be put to several uses: it could be used as a representation of reality, or a blueprint for something to make real, etc. The drawing is the idea, and one thing you’ll can do with that drawn is say “this represents reality”. The use of it as a representation, and the accuracy of it as a representation, is not a part of the drawing—the idea—itself.
For instance, the idea that “planet Earth has trees on it” can be either a truth or a falsity given what employment(s) of it? — javra
For clarity I would phrase that as “the idea of planet earth HAVING trees on it”, “having” in the gerund mood, with the indicative mood “has” in “planet earth HAS trees on it” instead showing the employment of that idea as a representation, and the usefulness or correctness of that use as representation determining whether that indicative statement is true or false.
Your implicit assumption here is that two people cannot create the same idea because an idea cannot physically be in two places at once. — Luke
It has nothing to do with that. Ideas aren’t concrete, so they don’t have locations. I say they also don’t have temporal location, or any other temporal features; they don’t come into being or go out of being or change over time, which is the main reason why I think it makes no sense to say a human being at some point created an idea. Abstract things aren't in space and time like that.
But the argument I've been making about that toward you, since you think they can come into being over time (by being created, invented) is about the incoherence of two people separately bringing into existence the idea. So you think the idea didn't exist before, from the dawn of time until some day one person brought it into existence, then later another person separately... brought something that already existed into existence, again? That doesn't make sense. The only way it can make sense that two people both did an act of creation, that each separately brought an idea into existence, is if they are two separate ideas that got brought into existence. But that would mean that those two people didn't separately come up with
the same idea, they just came up with two different, but identical, ideas.
Except we already agree that that's not correct, so then you have to follow the chain of inferences backwards,
contrapositively: since those two people didn't come up with two different ideas, but if they had each brought an idea into being they would have, they must not have each brought an idea into being. You might want to say that the first one brought the idea into being, but not the second; except then you're still denying what we've both already affirmed, that two people can independently come up with the same idea. So it must be that neither of those two people coming up with that idea brought it into being. Which means whatever the state of existence we can ascribe to the idea after they came up with it, we must also ascribe to it before they came up with it.
That could be that it neither existed before nor after. It could be that it existed before and after. It could be that "existence" is a confused thing to ascribe to an abstract object in the first place. I'm not taking a stance here on the ontology of abstract objects, like you and
@Tristan L are arguing about. (I have one, and I'm pretty sure it's not the same as either of yours; going to do a thread about that soonish).
But one way or another its state of existence didn't change when someone came up with it, or else two people couldn't have both separately come up with it.