The conceptual distinction between representational vehicles and representational contents is very old, probably older than Plato.
Lately, however, I’ve been wondering when the first use of this actual terminology emerged. Pete Mandik took time out from hammering brains to tell me he thinks the first use of this terminology might be from Dennett and Kinsborn (1992):
[T]he general principle of the content/vehicle distinction is relevant to information-processing models of the brain in ways that have not been well appreciated.
In general, we must distinguish features of representings from the features of representeds; someone can shout “softly, on tiptoe” at the top of his lungs, there are gigantic pictures of microscopic objects, and oil paintings of artists making charcoal sketches. The top sentence of a written description of a standing man need not describe his head, nor the bottom sentence his feet. To suppose otherwise is to confusedly superimpose two different spaces: the representing space and the represented space.
Is that the first mention of the ‘content/vehicle’ distinction in those words?
Of course conceptually this distinction has been known probably forever. In one of my favorite examples it is used to construct a clever little paradox. The following is from Frank Ramsey (1935), but he attributes the proof to Weyl:
Some adjectives have meanings which are predicates of the adjective word itself; thus the word ‘short’ is short, but the word ‘long’ is not long. Let us call adjectives whose meanings are predicates of the them, like ‘short’, autological; others heterological. Now is ‘heterological’ heterological? If it is, its meaning is not a predicate of it; that is, it is not heterological. But if it is not heterological, its meaning is a predicate of it, and therefore it is heterological. So we have a complete contradiction.
Take that, Frege!
Finally, I did find a tantalizing case in which ‘meaning’ was contrasted with ‘vehicle’ from a book published in 1722, but it seems clear this isn’t the same distinction as our content/vehicle distinction. Rather, Wollaston basically says that the body is a vehicle like a cart is a vehicle, and it carries the nonmaterial meanings as a passenger. From Wollaston (1722):
In short, words seem to be as it were bodies or vehicles to the sense or meaning, which is the spiritual part, and which without the other can hardly be fixed in the mind.
Italics are in the original (though on many browsers the entire quote will be italicized).
I received this response from Dennett on the origins of the distinction:
“Susan Hurley cites my 1991 (CONSCIOUSNESS EXPLAINED) and Millikan as the source. She was a good scholar. I bet she’s right.”
(The Millikan citation is her article ‘Perceptual Content and Fregean Myth’, also 1991)
In the comments someone pointed out that in 1990 Adrian Cussins employs the distinction in his ‘Connectionist Construction of Concepts’.
After a furious bout with google books and amazon search capacities, I think the winner may be Dennett:
Dennett, D. C. (1978), Toward a Cognitive Theory of Consciousness, in C.W. Savage, ed.,Minnesota Studies in the Philosophy of Science, Volume 9: Perception and Cognitions, Issues in the Foundation of Psychology. Minneapolis: University of Minnesota Press, pp. 201-228.
He uses the distinction a couple of times in nascent form. For instance:
The content of a particular vehicle of information, a particular information-bearing event or state, is and must be a function of its function in the system.
Content and Consciousness (p 56 1969):
The crucial point that emerges from this is that the candidates for vehicles of content or significance in the brain are compound.
Not sure what that means, exactly, but it looks like another incipient use of the distinction.
UPDATE 5 (July 2018):
Jim O’Shea pointed out this interesting discussion of the origin of the distinction over at philpapers, that occurred about a year before I posted this:
He also pointed out the following use of ‘vehicle’ from Anscombe’s Intention (1957/2000, Section 59):
…so the only thing that does happen is my intention; but where is that to be found? I mean: what is its vehicle? Is it formulated in words? And if so, what guarantees that I do form the words that I intend? for the formulation of the words is itself an intentional act. And if the intention has no vehicle that is guaranteed, then what is there left for it to be but a bombination in a vacuum.
This certainly seems to be an early use of the ‘vehicle’ of a content, though without a full-blown ‘content/vehicle’ distinction made explicit as it was made in Dennett.
Anscombe, G. E. M. Intention. Cambridge, MA: Harvard University Press, 2000.
Daniel Dennett and Marcel Kinsbourne (1992) Time and the observer: the whereand when of consciousness in the brain. Behavioral and Brain Sciences,15, 183-247.
Ramsey, FP (1931) Foundations of Mathematics, Routledge, London.
William Wollaston (1722) The religion of nature delineated (quote is taken from 1725, 3rd ed J Palmer, London).