The Meaning of ‘Meaning’

Breaking with internalism

Putnam’s central move is to break with the traditional view that meaning is something “in the head.” He argues that words like water don’t get their meaning from some private mental description (e.g., “clear, drinkable liquid”), but from their relationship to the external world and to social linguistic practices.

This challenges the descriptivist tradition running from Frege through Russell, which held that the meaning of a term could be captured by a description or set of properties that speakers associate with it. If meaning were purely mental—determined by the concepts in our heads—then two people with identical mental states should mean the same thing by their words.

The Twin Earth thought experiment

Putnam’s Twin Earth thought experiment drives this home: imagine a planet identical to Earth except that what its inhabitants call “water” is not H₂O but some other chemical, XYZ. The substance looks, tastes, and behaves exactly like water in every observable way. Twin Earthlings are psychologically identical to Earthlings—they have the same mental concepts, the same internal experiences.

Yet despite this psychological identity, their word “water” refers to different substances:

• On Earth, “water” refers to H₂O
• On Twin Earth, “water” refers to XYZ

If two speakers can be in identical mental states whilst their words refer to different things, then meaning cannot be purely mental. The reference of “water” depends on which substance actually exists in the speaker’s environment—an external, worldly fact.

Extension and intension

Putnam distinguishes between:

• Extension: What a term actually picks out in the world (the set of things it refers to)
• Intension: The mental concept or description associated with the term

Traditional theories assumed that intension determines extension—that our mental grasp of a concept fixes what it refers to. Putnam shows this is wrong: extension depends partly on external factors beyond our mental states.

As he famously puts it: “meanings ain’t in the head.”

The division of linguistic labour

Putnam also emphasises that reference is often secured by the social division of linguistic labour. Ordinary speakers rely on experts (like chemists or botanists) to fix what “water” or “elm” really refers to.

Most people cannot distinguish an elm from a beech tree, yet their use of “elm” successfully refers to elms because:

• There are experts who can make the distinction
• The linguistic community defers to these experts for the correct application of the term
• Reference is socially distributed, not individually possessed

This social dimension further undermines individualist theories of meaning. You don’t need to know the chemical structure of water, or how to identify an elm, for your words to successfully refer. Meaning is anchored by the community’s practices and the world itself, not by individual mental contents alone.

Semantic externalism

The result is externalism: linguistic meaning cannot be reduced to internal mental states. What your words mean depends on:

1. Environmental facts (what substances actually exist around you)
2. Social facts (the linguistic community’s practices and expert knowledge)
3. Historical facts (causal chains connecting your word-use to initial acts of reference)

This reshapes debates in philosophy of language, mind, and epistemology by:

• Challenging descriptivist theories of reference
• Paving the way for causal theories of reference (developed by Kripke and others)
• Influencing later externalist views in mental content and epistemology
• Questioning the Cartesian assumption that we have privileged access to our own mental states

Implications

If meaning isn’t in the head, then:

• Self-knowledge becomes problematic: You might not know what you mean by your own words
• Translation becomes complex: Perfect psychological similarity doesn’t guarantee semantic equivalence
• Mental content is world-involving: What you think about depends on what exists around you, not just your internal states

Putnam’s argument fundamentally challenges the idea that the mind is a self-contained theatre of meanings. Instead, mind and world are entangled: to understand what we mean and think, we must look beyond the skull to the environment and community in which we’re embedded.

Critical engagement

While enormously influential, Putnam’s externalism raises questions:

• How much expertise is required for successful reference?
• Can we explain communication if speakers don’t share the same meanings?
• Does externalism collapse the distinction between meaning and reference?
• What happens when expert opinion changes—do word meanings change too?

These debates continue to shape contemporary philosophy of language and mind, with externalism remaining a dominant (though contested) position.

Further reading

• Putnam, H. (1975). “The Meaning of ‘Meaning’”, in Mind, Language and Reality: Philosophical Papers, Volume 2
• Kripke, S. (1980). Naming and Necessity
• Burge, T. (1979). “Individualism and the Mental”