Round Up The Usual Suspects: Knowledge Based Metaphor Generation
The elasticity of metaphor as a communication strategy has spurred philosophers to question its ability to mean anything at all. If a metaphor can elicit different responses from different people in varying contexts, how can one say it has a single meaning? Davidson has argued that metaphors have no special or secondary meaning, and must thus mean exactly what they seem to mean on the surface. It is this literally anomalous meaning that directs us to the pragmatic inferences that a speaker actually wishes us to explore. Conveniently, this laissez faire strategy assumes that metaphors are crafted from apt knowledge by speakers with real communicative intent, allowing useful inference to be extracted from their words. But this assumption is not valid in the case of many machine generated metaphors that merely echo the linguistic form but lack the actual substance of real metaphors. We present here an open public resource with which a metaphor generation system can give its figurative efforts real meaning. 1 The Dreamwork of Language Metaphor is the rubber cement of language. Not only does it help us to the plug holes on our lexica, we also use it to fill the gaps in our understanding and to hide the cracks in our arguments. For unlike the brittle plaster of literal language, metaphors are elastic and can readily expand to fit our meanings in a shifting conversational context. This elasticity comes at a price, though one which a master orator is happy to pay: our metaphors are elastic because they are indeterminate, underspecified and vague. Like dreams, our metaphors paint vivid pictures with words, albeit with fuzzy and ill defined edges. Like dreams, metaphors can be highly suggestive, yet leave us feeling confused and uncertain. If metaphorical images are crisp at their focal points but hazy and dreamlike at their edges, just what is the meaning of any metaphor? The philosopher Donald Davidson (1978) has controversially argued that, like our dreams, our metaphors do not have well defined meanings, at least not of a kind that an AI researcher, semanticist or computational linguist could squeeze into a symbolic structure. Rather, metaphors can move us to think and feel in certain ways, and perhaps act in certain ways, but like dreams, two analysts (a Jungian and a Freudian, say) can hold conflicting views as to how they should be interpreted and as to what they actually "mean" if anything. So, for Davidson, a metaphor means just what it purports to mean on the surface, that is, what the literal or dictionary senses of its words suggest that it means. This meaning is to be distinguished from the panoply of inferences and insights that might later emerge from a metaphor, for regardless of how salient these may seem, they cannot be considered its definitive meaning. Freud once joked that when it comes to dreams, a cigar is often just a cigar. For Davidson, a figurative cigar is always a cigar, even if the metaphor spurs us to further inference far beyond the realm of tobacco. If all metaphors mean simply what they seem to mean on the surface, and most from the very best to the truly awful are superficially anomalous, how can we tell the good from the bad by simply looking? Indeed, how can we tell real metaphors from fake metaphors based only on the words they use and their senses in the dictionary? Empirical results seem to bear out Davidson's intuitions regarding our folk grasp of metaphors. Veale (2015)