seeing one idea with the aid of another. Many of our metaphors for metaphor are metaphors of seeing, for seeing often leads to knowing, or at least to an impression of knowing. So a metaphor can be a viewfinder, a magnifying glass, a microscope, a lens, a window, a pair of conceptual spectacles, a distorting fun-house mirror, and even a set of conceptual blinders. Max Black, the philosopher who more than anyone else kickstarted the modern resurgence in metaphor research, described a metaphor as working much like a blackened piece of glass onto which a specific pattern of lines has been etched [Black, 1962]. Looking through this bespoke glass, we see only those parts of a target domain that the etched pattern allows us to see, and see these parts in clearer relation to each other precisely because we are not distracted by the many parts we cannot see. Metaphor prompts us to look, helps us to see, and then controls what we can see.
Metaphor has existed longer than our need to describe its function, and much longer than our need to name it as a distinct linguistic or cognitive phenomenon. Indeed, the word “metaphor” is itself founded on a metaphor, to carry (-phor) above and across (meta-) a signifier from one realm of experience to another. The Greek philosopher Aristotle, to whom we can trace the earliest use of the term, effectively describes metaphor as a form of semiotic displacement, in which our agreed signifier for one object, idea, or experience is deliberately displaced onto another. But metaphor is not the only kind of semiotic displacement in language. Punning, for instance, involves the temporary replacement of one signifier with another, based on the phonetic similarity of the two, as in “mail” and “male” (e.g., “Q: Is that the mail plane coming in to land? A: Of course it’s a male plane, can’t you see its undercarriage?”). Synecdoche licenses the displacement of a signifier of a part onto the whole to which it belongs (e.g., “brains” stands for clever (or brainy) people in “the American and Russian militaries competed to round up the brains of the German rocket program”), while metonymy licenses a more general displacement of a signifier onto an object or idea that is functionally or conceptually related to its conventional signification (e.g., when Raymond Chandler’s private investigator Philip Marlowe says “Trouble is my business,” he means “My business concerns other people’s troubles, which invariably cause trouble for me;” so the metonymy tightens the relation between Marlowe and trouble). Aristotle is thus careful to enumerate the particular kinds of displacement that constitute a metaphor, as opposed to any other kind of semiotic play, and in his Poetics he offers the following schematic specification (as translated by Hutton [1982]):
Metaphor is the application to one thing of the name belonging to another. We may apply:
(a) the name of a genus to one of its species, or
(b) the name of one species to its genus, or
(c) the name of one species to another of the same genus, or
(d) the transfer may be based on a proportion.
The target of the name shift is typically called the topic, the tenor, or simply the target of the metaphor, while the source of the shift—the name belonging to another—is typically called the vehicle or simply the source of the metaphor. The designations source and target are generally preferred in the analogical literature (e.g., Gentner [1983]), although vehicle is more in keeping with Aristotle’s view of metaphor as a carrier of meaning across domains. Throughout this book we shall use the terminology of source domain and target domain to denote the space of ideas associated with the source (or vehicle) and the target (or tenor) respectively. The word domain has no formal definition; we use it, as others do, to designate the cluster of related concepts, properties, and norms that attach to a particular source or target so that we may later speak of transferring, mapping, or projecting content from one domain onto another. With this in mind, Aristotle offers an illustrative use-case for each of his four displacement strategies.
(a) Genus to species: “Here stands my ship” employs the generic (genus) term “to stand still” as a replacement for its specialization (species) “to be at anchor.”
(b) Species to genus: “Truly ten thousand noble deeds hath Odysseus done” uses “ten thousand deeds” as a specialization of the vague genus term “large number.”
(c) Species to species: “Drawing off the life with bronze” and “Cutting off the water with unwearied bronze” each employ a specialization of the genus “to take away.”
(d) Proportional analogy: “The wine cup is to Dionysus as the shield is to Ares” is an obvious statement of the proportion Dionysus:Cup::Ares:Shield, yet it supports more subtle allusions, such as the poetic use of “the cup of Ares” to refer to a battle shield, or “the shield of Dionysus” to refer to a wine cup.
So, metaphor distinguishes itself from other forms of semiotic displacement by its reliance on the vertical operations of generalization and specialization. Metaphor allows us to move signifiers up and down a hierarchy of concepts, and supports the sideways movement of signifiers only insofar as they achieve such movement by climbing up from one domain so as to climb down into another. In effect, Aristotle provides a strong account of the “what” of metaphor, and a reasonable account of the “how,” but offers very little on the “why” of metaphor, other than to suggest that it is done in a spirit of semiotic sport. The strategies in (a) to (d) above focus mainly on those uses of metaphor where the vehicle is explicitly given (e.g., the cup of Ares or ten thousand deeds) and a listener must work out the identity of the implied tenor (e.g., a shield, or a large number). But what of metaphors where tenor/target and vehicle/source are both explicitly given, as in the copula metaphor “marriage is slavery?”
Such metaphors appear to instantiate strategy (c) in Aristotle’s scheme, in which one species of an unstated genus is mapped to another of the same genus. Presumably it is the identification of this unstated genus term—perhaps cruel practice or social institution in the case of marriage as slavery—that offers the key to the metaphor. Yet, if so, the metaphor degenerates into an example of strategy (b) and communicates only as much information as this genus can offer. In fact, if the listener does not possess the same conceptual hierarchy as the speaker—for instance, the listener may not view even slavery as a cruel practice, much less marriage—then the metaphor will fail. However, one need not agree with a metaphor to understand its purpose, and many metaphors are designed to change a listener’s conceptual structures rather than to merely reflect them. So, in an important sense, the “why” of metaphor is precisely this: speakers often use metaphors to align the conceptual systems of others to that of their own.
For a metaphor is not a statement of fact, and most are more than the mere expression of a subjective viewpoint. Rather, a metaphor is an invitation to build a joint meaning space, as framed by the given viewpoint. The metaphor “marriage is slavery” is a communicative gambit that asks the listener to think about, and perhaps argue about, the idea that our concept of marriage can be meaningfully framed by our concept of slavery. In other words, the metaphor aims to establish what Brennan and Clark [1996] call a conceptual pact, and is a request that can be paraphrased as follows: “let us agree to talk about marriage using the words and ideas we normally associate with slavery; to this end, let us go so far as to suspend disbelief and assume that marriage really is a kind of slavery, and thereby explore the extent to which our concept of marriage can be subsumed under our concept of slavery.” The longwindedness of this paraphrase goes some way toward conveying the true utility of metaphor as much more than a flourish of language or a playful exercise in semiotic sport.
The metaphor “marriage is slavery” is an effective prompt to build a complex meaning space because “slavery” is itself an effective shorthand for a rich body of cultural knowledge and expectations.
