Refuting Putnam's Twin Earth Argument

In Hillary Putnam’s Twin Earth argument he is trying to disprove the notion that to mean something is to be in a certain psychological state. He has several examples but I think the best one is his example with jadeite and nephrite. It was once thought that all jades were identical, but we later learned that there are two distinct types of jade, jadeite whose chemical composition is NaAlSi2O6 and nephrite whose chemical composition is Ca2(Mg,Fe)5Si8O22(OH)2. Putnam’s argument is that two speakers can point to both of them and say “This is jade,” which will put them in the same psychological state but they will mean different things. In standard form here is Putnam’s argument:

  1. If two speakers say: “This is jade,” then they are both in the same psychological state.
  2. There are two types of jade: jadeite and nephrite, which appear to the naked eye to be the same, though in reality they have a different chemical composition.
  3. Jadeite means jadeite and nephrite means nephrite.
  4. If one speaker calls jadeite jade and another calls nephrite jade, then they are both in the same psychological state and they mean different things.
  5. If two speakers are in the same psychological state and they mean different things, then psychological state does not determine meaning.
  6. If psychological state does not determine meaning, then meaning is not in the head.

The flaw in Putnam’s argument lies on premise four. The two speakers do not mean different things, they mean the same thing but they are unaware that there are two types of jade. What Putnam is unaware of is:

  • If I say “X is true” and I’m wrong, then I still mean “X is true.”

Meaning is a property of information iff the information refers to another thing, be it in the world or be it in the mind. Therefore, meaning can be found in the head or out in the world. People mean things and objects mean things, for example, the meaning of a destroyed bridge which you desire to cross is that you can’t cross it. The meaning of a person uttering a certain sound is that the person uttering the sounds has a belief or a desire. It does not matter if the belief is a false belief, the person still means that belief, or they intend for us to understand that belief. So if a person says: “This is a jade,” and another says “This is jade,” but it turns out that one is really nephrite and the other is jadeite, the two people still mean what they say, in other words, they still intend for us to believe them, it just so happens that they are wrong in that there are two types of jade. In revised form, the argument should go as follows:

  1. If two speakers say: “This is jade,” then they are both in the same psychological state.
  2. There are two types of jade: jadeite and nephrite, which appear to the naked eye to be the same, though in reality they have a different chemical composition.
  3. Jadeite means jadeite and nephrite means nephrite.
  4. If one speaker calls jadeite jade and another calls nephrite jade, then two speakers are both in the same psychological state and the two speakers mean the same thing, although they are wrong.
  5. If two speakers mean X is true and are wrong, then they still mean X is true and are in the same psychological state.
  6. If two speakers are in the same psychological state and they mean the same thing although they are wrong, then psychological state can still mean something.
  7. If psychological state can mean something, then some meaning is in the head.

What’s unclear to me about the argument is this:

There are two speakers, one of them pointing to Nephrite and the other to Jadite, right? What’s unclear is, would each of those speakers also be willing to point to the other and also call it Jade?

In other words, Person A is pointing to Jadite and calling it Jade, person B pointing to Nephrite.
But, if Person A were shown Nephrite and person B Jadite, would they also call that Jade?
If they would, then they mean the same thing (approximately).
If not, then they mean different things, but I would dispute that they’re in the same psychological state then.

I also don’t know why they’re ‘wrong’. You say ‘there are two types of Jade, jadite and nephrite’. If you think that, then…how is it wrong to point to nephrite or jadite and say it’s jade? If both of those are types of jade, then it seems not-wrong to me.

Maybe I should have been a bit more clear that they are pointing to jade before it was discovered that there are two types of jade. Let’s say they’re pointing to jade and it is the year 1850. Then in say 1950 we learned that there are two types of jade.

So they both do mean the same thing, and neither of them are wrong?

Are you saying Putnam is in error or my interpretation of Putnam is in error.

P4 would only make sense if they knew about the distinction beforehand. That way they could mean different things if each were to say “Only this is jade.”

But both mean Jade, per P2.

Neither are wrong. They are both jade, albeit different types. Both mean the same thing.

Maybe Putnam sees them as reasoning from their beliefs rather than from something in the world they don’t yet know.

If both guys believe it’s jade and they say both things are jade then if you’re just matching up statements with beliefs then you’d have something to go on.

This also makes me think about how we use the term “green” to describe hundreds of different colors, and we recognize that “green” symbolizes a category rather than a particular instance of one thing.

Maybe by psychological state, he means something like, “they are both holding the belief that they have been confronted with an object that they believe to be jade”.

He could be talking toward the notion that “meaning” is purely distinct from the object itself (in the kantian sense) if he’s a real live skeptic about epistemology.

I’ve found that a lot of the analytic types have this tendency to just wanna fix up regular language so that all of it’s eventually formalized and therefore they accept a decent amount of equivocation, or generalization when it comes to labeling objects.

I could be wrong entirely.

What’s the question here really?

I find this a very confusing OP. It’s essential to the twin worlds argument (at least as I understand it) that they don’t know anything about the existence of the “other” jade. The original, most famous example is “water”. See here: … experiment

The point is that the material, whichever it is, occupies the same role in their lives, but is in fact a different material (so presumably, from Putnam’s argument, they would not call it by the same name). There’s no reason for them to have a different mental state if it appears the same and fulfils the same role and they are ignorant of the alternatives, but it refers to something chemically different.

In any case, I’d recommend reading the original rather than trying to second-guess it from the OP.

If all the speakers of a language define X to mean something, they’re not “wrong”; they can’t be. The use of a language is solely dependent on its speakers. If they are all unaware that there is another material called jade, that means that the other material is not called jade. Because no-one is even aware of the material, much less uses the word “jade” (which is already in use) to define it.

Sweet Jesus Humean.

You just gave me a flashback. I remember now. The water thing. This is one of the guys I had to read when I was reading all that damn David Lewis.

Seems to me the whole thing is semantically misconceived.
it looks like Putnum has not yet got his head out of Platonic Forms.

The conclusion has nothing to do with meaning at all.
First, no one can share the same psychological state. We are all unique beings an each state, from moment to moment is not only unique between people, it is also unique to the self. One is never the same person from moment to moment; you can’t step into the same river twice.
But in there own way they both mean what they say. They means to say what they consider to be jade and have their own definitions that confirm their statements.
It simply does not follow that meaning exists outside people. It just means that Putnam thinks his meaning lies outside on people, but in truth it lies within Putnam.
For my money the whole problem is meaningless. And that meaninglessness lies within me. Putnman’s meaning is just wrong, that makes him wrong. and what the problem is really about is.
What lies outside is nothing whatever. Objectivity, and the truth about how we choose to define things like “jade”, only exist because people choose to agree upon those definitions.

Hobbes what about types? Are those forms? I think you think everything is a token and that we have to talk in types and that it kind of sucks. I could agree with you maybe. But what if we said that they shared the same type or kind of psychological state? What would that do?

You could say that the totality of the “psychological state” of a person is a nebulous combination of inputs and outputs and private internal qualitative states and some quantifiable chemical states and it’s be pretty easy to come up with some way to say there are infinite combinations and therefore each is unique, but the type guys are gonna come in and be like…“pshhhh there’s just a handful of types psychological states and therefore everyone shares one with a good number of other people and none of them are unique.”

It’s like a fight over what identity has to mean if it’s going to hold up. Some people point to similarities between two objects and call em identical, and others point to differences between the same two objects and call them distinct. The rhetoric gets real thick and nasty and in the end no one wants to admit that the distinctions are flawed even though it’s shown by the whole fact that each object has properties that fall on each side of each distinction. Every. Time.

I dunno man.

Jade is the name given to a stone that’s soft enough to be carved, is usually green, and has been used for centuries by Asians for all sorts of things. It isn’t always green. Jadeite can be pink, blue, mauve–and nephrite can be white. Nephrite can be a bit softer than jadeite. But they’re all called ‘jade.’

If there’s a problem with Putnam it’s in his use of jade as an example of an hypothesis about twin earths–or it may not be. Not having read Putnam or his twin earth argument, it’s hard to say. In appearance, workability, and uses, jadite and nephrite are the same. That may be what Putnam is getting at.

If you haven’t been welcomed to ILP before, 117, let me do so now. Please explain more about Putnam’s argument. Thanks. :slight_smile:

Yah you do.

That’s the one. It’s a bit more clear an example than the jade, IMO.

I think that’s an inaccurate summary of his position, although if it’s based on the argument presented in the thread, it’s clear why :stuck_out_tongue:

The point is that even if they are the same, meaning can be different. Not that they are the same, or could be the same.

Quite; nowhere does Putnam declare that there is some Platonic form that dictates whether those choices are “correct” or not. The point he is making is more that the reasons people agree on definitions is dependent upon the roles the words (and their referents) play in their lives, and that is something outside ones head. It’s more Wittgenstein than Plato.

No, because in the water example, you have to imagine some bizarre Twin Earth that can’t exist. If water is different then a lot of other things are different such as mud, beer, cars, food, humans. With Jade you don’t have to imagine a bizarre different world that can’t exist anyway. When using thought experiment you should always appeal to something that does exist or could exist, rather than something that might not exist.

I get what you are saying, but I’m not sure it is possible to conclude that. All meaning is in the head. That is where the agreement happens; it is where the definitions are agreed; it is where the referents are stored. To claim it is not, is a Platonic claim. because that would mean that meaning is outside the head which is absurd. I mean to say - where exactly?
Even if a book says “Jade is X”, that is not meaningful until it is understood. That is an internal meaning. The ‘meaning in the book’ relies fully on the ability to read and understand.

That’s it, right there. It’s just a stupidity. That’s Putnam’s real problem.

Aha! I looked it up! It’s a thought experiment! I didn’t think thought experiments were meant to come up with answers–I thought they were designed to make one think! From what I read, Putnam ended up disagreeing with himself. Maybe that’s enough of a refutation. :slight_smile:

Well, nowhere. It’s not a Thing. His point is not that it’s somewhere other than the head; it’s just not a mental process, or a configuration of neurons. It’s contextual, social; to say that anything but a physical-reductionist stance is Platonism seems to be lumping a lot of very unrelated stances together.

Putnam is famous for disagreeing with himself, repeatedly :slight_smile: I think internal disagreements and developments make philosophers more interesting!