But then we are relying on sensory experience; suppose the simulation hypothesis were true, then that sensory experience would be unchanged, but the rock wouldn’t really exist, would it?
No. Look, if you think rocks exist now learning spooky metaphysical things about the nature of the universe should not change that belief. ‘Rock’ is just an entity our model of reality uses to help us make predictions and control things. That’s what it means for something to exist.
Now, lots of mathematical objects are useful entities to have in our model. So we can say they exist- of course they aren’t variables in the causal model, they’re isomorphs of variables and the structure in the model that help us use the model more effectively. We’ll call these entities ‘abstract’ and the actually causal variables in the model ‘concrete’.
Whether or not there are other universes where abstract objects are concrete objects seems like an open question to me and not something that can be answered with philosophical speculation.
I don’t think there is a clear distinction between science and philosophy- so yeah it can contribute to the answer. My point is more that the question is contingent in the same way that, say, physics is contingent. If the scientific-philosophical enterprise ever outputs the Tegmark Level 4 multiverse: cool. But you don’t get there through mere reflection on the meanings of words (if the history of philosophy teaches us anything...).
No. Look, if you think rocks exist now learning spooky metaphysical things about the nature of the universe should not change that belief. ‘Rock’ is just an entity our model of reality uses to help us make predictions and control things. That’s what it means for something to exist.
Now, lots of mathematical objects are useful entities to have in our model. So we can say they exist- of course they aren’t variables in the causal model, they’re isomorphs of variables and the structure in the model that help us use the model more effectively. We’ll call these entities ‘abstract’ and the actually causal variables in the model ‘concrete’.
Whether or not there are other universes where abstract objects are concrete objects seems like an open question to me and not something that can be answered with philosophical speculation.
This implies you believe that it is logically possible, so you do think philosophical speculation can contribute to seeking the answer.
I don’t think there is a clear distinction between science and philosophy- so yeah it can contribute to the answer. My point is more that the question is contingent in the same way that, say, physics is contingent. If the scientific-philosophical enterprise ever outputs the Tegmark Level 4 multiverse: cool. But you don’t get there through mere reflection on the meanings of words (if the history of philosophy teaches us anything...).