Of course heavy water is different to ordinary water . That’s not the point. The point is that in Putnam’s Twin Earth thought experiment, it is never asserted that XYZ is completely indistinguishable from water. The point is only that something similar sufficiently similar would have been called water when we started using the word thousands of years ago… thousands of years before a scientific understanding of water.
This sort of thing happens in our world too. For instance the “wasabi” available in the West is not wasabi.
The point of Poundstone’s exploration (which I independently endorse, having bought its claim) is that no such sufficiently similar substance can exist. That there’s a big gap between water and the next nearest physically possible alternative.
Heavy water being an example of something that would absolutely not fit the bill of “sufficiently similar” to water.
My concern, which I interpret as being TAG’s point (but with different words), is that your example of water vs. XYZ is immediately traceable (at least for anyone who knows the philosophical discussion) to Putnam’s Twin Earth experiment. The way you express your point suggests you disregard this thought experiment—which is surprising for someone acquainted with it, because Putnam (at least when he wrote the paper) would likely agree that a substance with the same basic chemical properties of water would be water. He actually aims to provide an argument for semantic externalism—i.e., the idea that the meaning of “water” (or of other natural species) is H20, its chemical nature, and not the apparent properties commonly used as criteria to discriminate it (that it’s a tasteless liquid...). He’s so pushing against a conventionalist view about semantics (and philosophy of language), thus it’s not about physics or ontology.
But we almost certainly are talking past each other , because Twin Earth isn’t really about water..it’s about naming and necessity . Any example where naming is contingent would have done .
Can you imagine a planet where all the water is heavy water?
I can. I am not sure if that ability-to-imagine reflects the same sort of failure-to-notice-consequences.
EDIT: this would seem to indicate that it does.
Of course heavy water is different to ordinary water . That’s not the point. The point is that in Putnam’s Twin Earth thought experiment, it is never asserted that XYZ is completely indistinguishable from water. The point is only that something similar sufficiently similar would have been called water when we started using the word thousands of years ago… thousands of years before a scientific understanding of water.
This sort of thing happens in our world too. For instance the “wasabi” available in the West is not wasabi.
I think we’re talking past each other.
The point of Poundstone’s exploration (which I independently endorse, having bought its claim) is that no such sufficiently similar substance can exist. That there’s a big gap between water and the next nearest physically possible alternative.
Heavy water being an example of something that would absolutely not fit the bill of “sufficiently similar” to water.
My concern, which I interpret as being TAG’s point (but with different words), is that your example of water vs. XYZ is immediately traceable (at least for anyone who knows the philosophical discussion) to Putnam’s Twin Earth experiment. The way you express your point suggests you disregard this thought experiment—which is surprising for someone acquainted with it, because Putnam (at least when he wrote the paper) would likely agree that a substance with the same basic chemical properties of water would be water. He actually aims to provide an argument for semantic externalism—i.e., the idea that the meaning of “water” (or of other natural species) is H20, its chemical nature, and not the apparent properties commonly used as criteria to discriminate it (that it’s a tasteless liquid...). He’s so pushing against a conventionalist view about semantics (and philosophy of language), thus it’s not about physics or ontology.
Under which laws of physics?
But we almost certainly are talking past each other , because Twin Earth isn’t really about water..it’s about naming and necessity . Any example where naming is contingent would have done .