For example, there are possible worlds in which the laws of physics are radically different from those that actually operate, including some with laws that would make it impossible for human beings to exist. Obviously such possibilities cannot depend on the actual material world (which, needless to say, is governed by the laws that actually hold) [rebutting nominalism] or the human mind [rebutting conceptualism]. And before the actual material world or any human mind came into existence, it was at least possible for them to exist. This possibility could not then have depended on either the actual material world [again rebutting nominalism] or the human mind [again rebutting conceptualism], since neither yet existed.
-Realism says abstract objects such as possible worlds are real and objective.
-Nominalism says abstract objects such as possible worlds aren’t real. Possibility must instead be grounded in the material world.
-Conceptualism says abstract objects such as possible worlds are real but exist only in the human mind. — AJJ
Nominalism comes in at least two varieties. In one of them it is the rejection of abstract objects; in the other it is the rejection of universals. Philosophers have often found it necessary to postulate either abstract objects or universals.
The definitions given in the OP are correct for the purpose of the point being made. — AJJ
The definitions, for example, say that nominalists are necessarily materialists. This is wrong. — Terrapin Station
It says no such thing as "possibility must be grounded in the material world." — Terrapin Station
What part of "nominalists DO NOT say that possibility must be grounded in the material world" don't you understand? — Terrapin Station
If possible worlds have been rejected as existing in the abstract then possibility must be grounded in the material world. — AJJ
I already explained the alternative. One can simply posit nonmaterial particulars. "Not abstract" doesn't imply "material." (And likewise, "abstract" doesn't imply "not material.") — Terrapin Station
(And likewise, "abstract" doesn't imply "not material.") — Terrapin Station
And I Googled abstract and this is the first definition given: “existing in thought or as an idea but not having a physical or concrete existence”. — AJJ
Abstracts range over multiple instantiations of particulars, whether they're types/universals or concepts. — Terrapin Station
if you believe that abstracts are concepts, you believe that concepts are events in a specific individual's mind, and you're a physicalist on mind. — Terrapin Station
They do not necessarily reject abstracts as concepts. Hence we have conceptualist nominalists (which is what I am). — Terrapin Station
I don’t see how this applies to possible worlds, which I take to be discreet abstract objects. — AJJ
In that case concepts wouldn’t be abstract — AJJ
You'd have to explain how "discrete abstract" makes sense to you (unless you're simply using "abstract" as a synonym for "nonphysical," but I explained why that doesn't work). — Terrapin Station
They're abstract in terms of content, or in terms of semantics (meaning). Content-wise, they range of a number of particulars. That's the whole function of concepts. — Terrapin Station
“existing in thought or as an idea but not having a physical or concrete existence” — AJJ
So then, for one, in this context you'd be saying that possible worlds are objective thoughts or ideas? What would that amount to? — Terrapin Station
It would amount to there being either a Platonic third realm where those objects exist, or a divine intellect where they do. — AJJ
So we can't do possible worlds unless we buy platonism or god? — Terrapin Station
On my view, possible worlds are a way of talking about the simple fact that not everything about our world is strongly/causally deterministic. — Terrapin Station
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