Talk:Twin Earth thought experiment

message: Assuming that both of these substances are called "water", wouldn't that depend on whether "water" refers to
A) A use that XYZ/H2O is put to.
or 
B) What XYZ/H2O is made up of?
In other words, I believe whether or not "water" is the same on both Earths depends on context.
: There is a closely related debate in the Philosophy of Language along these lines. There are those who believe that the meaning of a term such as 'water' is determined by descriptions of it - similar to your A above. Putnam, and those who value the Twin Earth thought experiments, however, believe that at least in many cases, a term such as 'water' refers indexically to that particular stuff (which we call 'water') whatever it in fact is. - Ncsaint 20:07, 13 October 2005 (UTC)

message: Is this thought experiment supposed to be impressive? It seems to make no attempt at a true understanding of the world. -jjh
I concur somewhat, the thought experiment is entirely flawed because it is the incredibly peculiar property of water that causes it to expand when it freezes (i.e. grows when going from liquid to solid) that is greatly responsible for there being life on Earth.  The thought experiment might be better improved if you just had a world where cats were called dogs and vice versa.  There, in fact, we wouldn't really need a 'Twin Earth' we could just get two kids growing up, tell one that the pet is called a 'cat', tell the other 'dog', then argue about whether any of this helped anybody...ever?  Better yet, we could improve this experiment by having the actual animal involved as a monkey... by which I mean a fish. ;)  aj
I mostly agree with the two above comments (see my previous post in the section directly below) but I think (I have a math/physics background, not philosophy) this "thought experiment" is getting at (badly IMHO) is the distinction between what we use a word to describe (given our inherently subjective, limited and fuzzy knowledge of the named entity) and what it physically is (assuming you subscribe to Realism of course!). Annoyamouse (talk) 04:46, 10 November 2011 (UTC)
thread_title: WTF

message: In the thought experiment it says twin-water (XYZ) is chemically NOT water (H2O) - i.e. they are different molecules. It then contradicts this in the statement "their brains are molecule-for-molecule identical". Brains are mostly made of water (H2O), so twin-brains would be mostly twin-water (XYZ). Thus, their brains are NOT molecule-for-molecule identical! It is also a scientific fact that different chemical molecules tend to behave in significantly different ways, and specifically water (H2O) has very special and specific properties (especially in regards to biology) not shared by any other compounds, rendering such a thought experiment impossible. A planet with XYZ instead of H2O is very unlikely to evolve life as we know it, and would be in no way isomorphic to our own world. The thought experiment ignores the complexities of physical reality and the myriad changes that would result (think the butterfly effect in chaos theory) from replacing H2O with a different molecule. This is a well known danger in thought experiments when they diverge to far from the known state of affairs. Annoyamouse (talk) 04:31, 10 November 2011 (UTC)
thread_title: Flawed: Contradicts or diverges from the known state of affairs?

message: A line in the article says; 
"Putnam's original formulation of the experiment was this" 
and then in the quote, second paragraph, this sentence occurs;
"Yet, at least according to Putnam, when Oscar says water, the term refers to H2O..."
This leads me to believe that Putnam was speaking of himself in third person, something I doubt that he did. The wording "original formulation" makes me believe that this is actually Putnam's own words!
--Jambalaya 22:48, 7 September 2006 (UTC)
thread_title:  Putnam speaks of himself in third person? 

message: Tell a child that water is in fact called "waber" and he will spend the rest of his life calling it "waber" - unless he is corrected. Tell a child that orange juice is called "water" and the same will happen - unless somes one tells him different, he will call it "water". In the twin world, no one questions the fact that this mystery liquid is called water because they've all been brought up being told that it's called "water"... it's a name for this liquid and nothing more! Seriously, Putnam needs to put his time to more beneficial use! What a waste of space.
: Well, not all philosophers are a waste of space - and those that are tend only to waste space some of the time! For exmaple, the philosophical thought experiment of the Chinese room is quite valuable in thinking about artificial intelligence. SteveBaker 06:53, 8 September 2006 (UTC)
replies: text: I'll second SteveBaker here. I tend to read philosophy (especially ancient Greek) with a pinch of salt and view it generally as much less rigorous than math and the (hard) sciences; mind you, I have a math/physics background and so I could be bias. However, I think math, science and many subjects are severely weakened when devoid of philosophical debate. I really don't like the "shut up and calculate" school of thought. IMHO the interpretation and meaning of quantum mechanics is a good example of this type of debate, as is meta-mathematics like Godel's incompleteness theorem. I also agree with SteveBaker's comment on the Chinese room thought experiment and would add the related "Chinese nation" thought experiment too. IMHO philosophy without science is unfalsifiable, and science without philosophy is unimaginative; together they are more than their sum. Just my two cents. :-) Annoyamouse (talk) 05:09, 10 November 2011 (UTC)
thread_title: Just goes to prove that philosophers are a waste of space

message: Of course none of us actually, when we use the word water, have associated in our minds ALL of the properties of the substance we know as water with the word, or the image the word invokes.  Just as people once didn't have in their mental images of the word water the idea that it was composed of oxygen and hydrogen, we don't even now know water from every single possible viewpoint.  There are still properties of water we have never experienced.  There are still properties of all things in our physical universe that we haven't, and for some of those properties, will never, experience or know about.  We have only been experiencing some small portion of the real world all our lives.  As far as the twin earth argument, I don't believe it is possible to have two worlds with the only difference being the chemical composition of what is called water.  The universe is a nonlinear sort of place, so that any difference in initial condition, no matter how small, would result in vast differences between the state of the two worlds.  Perhaps the people on this twin earth would not even eat ice cream, since, if made with XYZ, it would taste thoroughly unappealing.  There would have to be some difference beyond the replacement of H2O with XYZ, as this would automatically produce differences elsewhere.  Putnam demonstrates not only his inability to reason through an argument to a profitable conclusion, but also his complete lack of knowledge of what an informed person now knows about water, chemistry, and physics.  It is even worse than his argument against brains in a vat being able to think about being brains in a vat, and just as useless.  —Preceding unsigned comment added by 74.226.64.128 (talk) 21:37, 27 November 2007 (UTC)
thread_title:  Well, duh. 

message: Consider that in Dennett's terms, intuition pump isn't pejorative at all, like it is suggested here. There can be good and bad thought experiments of course, but in general intuition pumps are very useful. Dennett himself is the inventor of numerous intuition pumps.
Not to mention that putting Dennett's allegedly negative attitude about intuition pumps as the argument against Twin Earth experiment seems to be entirely missed, because Dennett shares the intuition of Putnam's externalism regarding to mental content. His detailed view can be found in "Evolution, Error and Intentionality".
83.168.75.17 (talk) 11:35, 23 February 2008 (UTC)
thread_title:  Some remarks about Dennett 

message: This is the article right now: "Putnam, who is well known for changing his philosophical positions on a variety of issues, criticizes the experiment later in life because it is anti-functionalist." - in which way did he criticize it? Is there any source on this? Just saying that he critisized it gives very little important information. Ran4 (talk) 04:20, 24 April 2009 (UTC)
thread_title:  Which criticism? Source? 

message: A few remarks:
*The article lacks a conclusion that can be inferred or the conclusion that the author drew from the experiment, possibly one of the most important things. I, as someone who had never heard of this prior to reading this article, still don't know what the author was trying to prove with this mental experiment.
*Also, the section of objections is disproportionately larger than the rest of the article. Pikolas (talk) 05:37, 16 October 2011 (UTC)
thread_title:  Conclusion 

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thread_title:  External links modified 

message: Oscar and Twin Oscar's brains couldn't possibly be molecule-for-molecule identical, as Oscar's brain is comprised partially of H2O and Twin Oscar's of XYZ. The two papers referenced only claim that their psychological states are identical. Cocaineninja (talk) 15:59, 9 August 2019 (UTC)
thread_title:  Molecule-for-molecule identical?