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What, if anything, do Putnam's Twin Earth thought experiments demonstrate about meaning?With his Twin Earth thought experiments, Putnam attempts to demonstrate that the meaning of utterances is dependent on more than mental states. In this essay I hope to show how he attempts this and how he ultimately fails. While some discussion on mental states is warranted, I shall primarily be focussing on the meaning of words and the meaning of "meaning". Before we discuss Putnam though, some groundwork is required. "Mean" can mean many things, even ignoring homonyms such as "mean" in the sense of "cruel" or "mean" in the sense of "average". Grice separates them into natural and non-natural senses. [Grice, Reading 1, p180] Natural meaning is "mean" in the sense of "indicate", e.g. "the spots on your face mean you have measles" or "these tracks in the snow mean a fox has passed by". Natural meaning contains an implication of truth. If I say "these tracks mean a fox has passed by, but in fact a fox has not passed by" I am contradicting myself. However, I might be mistaken. Perhaps a badger made the tracks. Non-natural meaning does not contain an implication of truth. Rather, it is "mean" in the sense of "can be interpreted as", or "conveys the concept". I can say "the gong means that dinner is ready, but in fact dinner is not ready" without contradicting myself. When I ask "what does this word mean" I will normally be using "mean" in the non-natural sense. Unless specifically stated otherwise, this is the sense we shall be considering. When it comes to the meaning of words some further clarification is needed between the ideas of internal meaning and external meaning. The internal meaning of a word - the intension - is what the utterer understands by it. It is the concept of the word, or the set of criteria something must meet if it is to be what the word refers to. The external meaning - the extension or reference - is the set of things that meet these criteria. If we consider "water", the intension might be "clear, drinkable fluid, found in taps and oceans, used to make tea..." etc. while the extension is water itself. Different intensions may reference identical extensions. "Tony Blair" and "The British Prime Minister" both (currently) refer to the same person, but the set of criteria that defines each term is different. However, different extensions cannot be referred to by the same intension. The purpose of a set of criteria is, after all, to uniquely specify a single entity. [Barber, Chapter 3, p48] The theory of Linguistic Internalism states that an intension is solely determined by the utterer's mental states. It is this that Putnam aims to criticise. Let us now examine his thought experiment. Imagine a world which we shall call Twin Earth. It is identical to Earth in all ways but one. The substance they refer to as "water" - the substance in their taps, their tea, their lakes and oceans - is a different substance. It behaves in the same way, and has the same properties, but instead of H2O, it has a complex chemical formula we shall abbreviate to XYZ. Now rewind the scenario to the year 1750, when science is not yet advanced enough to know the chemical structure of water (or twin-water). On 1750's Earth, Oscar is drinking a glass of water. At the same time on 1750's Twin Earth, Twin-Oscar is drinking a glass of twin-water. They would both describe the liquid in their glass as "water". They are identical and have identical mental states, so their intensions for the word "water" are identical. Yet their extensions are different. Unbeknownst to them, Oscar is referring to H2O, Twin-Oscar to XYZ. [Putnam, Reading 3, pp193-194] Putnam argues that this demonstrates that meaning is dependent on more than mental states. Does it? Let's break down the argument.
Now we shall consider these steps in turn. Premise 1 is an assumption of the thought experiment. Premise 2 is the principle of "methodological solipsism", roughly that mental states depend on nothing outside of the subject's mind [Crane, Reading 4, p201]. Mental states so defined can be referred to as "narrow" mental states. In contrast, mental states that do depend on factors from the outside world are "wide" mental states. Putnam is attempting to criticise Internalism, which states that mental states determine intension (Premise 4). However, there is nothing in Internalism that necessarily requires those mental states to be narrow. A minor alteration in the definition of Internalism to accommodate wide mental states, and we can say that Oscar and Twin Oscar are in different mental states due to their different worlds. Putnam's argument loses its impact. However, this is not our focus, so we''l let it pass, and therefore accept Conclusion 3. Premises 4 and 5 are part of the definition of an intension. I shall skip Premise 6 for now and examine Premise 7. This states that the meaning of the word "water" does not change over time. This initially seems implausible. How else could Chaucer and Shakespeare be incomprehensible to modern readers? Consider the usage of "gay" now and fifty years ago. Anticipating the argument that this doesn't apply to natural-kind terms, consider "brimstone". Originally it referred to sulphur but now its meaning is wrapped up in ideas of hell and the occult. Putnam anticipates criticism of this premise, and gives the following justification. Suppose I have a standard sample of water. I can now define "water" as "anything that is the same substance as in this sample". No matter how much I learn about water, or how much society changes, the substance in my sample remains the same. Therefore the meaning of "water" remains the same. [Putnam, Reading 3, p194] This is the idea of indexical meaning. Words such as "here", "now" and "me" have indexical meanings. Their meaning depends on the context in which they are uttered. "Here" refers to the place of utterance. "Me" refers to the utterer. "Water" now refers to the standard sample, and anything that is the same as it. This neatly explains the difference between "water" and (twin) "water", as they refer to different samples. However, "aluminium", "wood", or any other natural-kind term can be defined using an identical definition by referring to a different sample. Yet "water" and "wood" are not the same word. This leads us to conclude that "water" and (twin) "water" aren't either, but are simply homonyms. This undermines the whole basis of the Twin Earth scenario. [Crane, Reading 4, p204]. However if "water" really was indexical, then the same word with the same intension will pick out water or twin-water depending on context in exactly the same way as words like "here" and "now". As with the case of wide mental states, it takes but a minor clarification in the definitions of Internalism to accommodate this, and once again the force of Putnam's argument is undermined. [Barber, Chapter 3, p60] However, Putnam's argument does not stand or fall on Premise 7. Provided we make clear that Oscar and Twin Oscar do not know the chemical structures of their respective waters, we need not rewind the scenario to 1750, and we need not claim that the meaning of "water" is unchanging. Let's return now to Premise 6, which states that "water" cannot refer to both Earth-water and twin-water. Suppose Oscar and Twin-Oscar are enjoying a glass of water together on a third, entirely different planet. Are they drinking earth-water or twin-water? Ask them what they are drinking, and they will both say "water". Neither are chemists, so neither are aware of the difference between earth-water and twin-water. The criteria of their intensions can be completely met by both substances. This is only a minor difference of degree from the fact that if I say "water" I could mean sea water, tap water, distilled water or mineral water. If I am specifically referring to sea water, my mental state will be slightly different. My intension will now include the criteria "comes from the sea" but not "suitable for drinking". However, I can only do this because I understand that sea water is different. [Barber, Chapter 3, p59] If an expert joins Oscar and Twin-Oscar and explains the difference between water and twin-water, their intensions would be updated with new criteria. However, if the distinction was not relevant to the conversation, they would most likely still use "water" to refer to both earth-water and twin-water, and to the unspecified water they are drinking. A similar criticism was raised by Crane using the example of superficially identical metals aluminium and molybdenum He argued that when non-experts used the word "aluminium" they could equally well mean molybdenum, and suggested their intension referenced the extension molyminium - a combined concept which included both metals. [Crane, Reading 4, p203] Claiming that two people mean the same thing when they clearly mean different things may seem counter-intuitive. In an attempt to clarify this, I'd like to re-examine the meaning of "meaning". [Barber, Chapter 3, pp59-60] I cause an utterance because I wish to communicate something. I choose suitable words that I believe will best convey what I intend to convey. My audience interprets the words, and attempts to extrapolate back to ascertain what I intended to convey. What I intended to convey is the intended meaning. What my audience thinks I intended to convey is the interpreted meaning. Critically though, interpreted meaning and intended meaning may differ. This is the familiar phenomena of misunderstanding. My choice of words is determined by the intensions I have of them, whereas my audience interprets my words using their own intensions, which may be different. Perhaps they have access to a different amount of technical knowledge, or are simply in a different mental state. Let's return now to Putnam. Oscar refers to "water". Twin-Oscar also refers to "water". Their intended meaning is identical because their mental states and thus their intensions are identical. Their meaning appears to be different because we - the readers - are the audience. We know there is a difference between water and twin-water, so when Oscar refers to "water" we are in a different mental state than when Twin-Oscar refers to "water". Therefore our interpreted meanings of their utterances differ. This is how two people can mean the same thing, yet appear to mean different things. Putnam attempts to demonstrate that the meaning of words depends on more than internal states. After examining his arguments, I have to conclude that he fails in this. However, he does demonstrate that wide mental states, indexical terms, and misinterpretation of intention are all things we must be aware of if we are to fully understand meaning. Bibliography
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