Tendahl and Gibbs: "Complementary perspectives on metaphor" (2008)

Tendahl and Gibbs argue in this (excessively long) paper that cognitive metaphor theory and relevance theory have something to learn from each other.

From Relevance Theory to Cognitive Metaphor Theory
Cognitive metaphor theory already relies on a notion of "relevant" aspects of a source domain. Understanding a metaphor, like any disambiguation process, requires a hearer to identify the plausible readings of an utterance.

Relevance theory consequently treats metaphors like it treats all sentences. It hypothesizes that we produce the reading that has minimal distance to the logical form of the sentence, and that has maximal relevance in given the context.

It is left relatively obscure how this mental algorithm decides in what order to examine the candidates; how it quantifies the relevance and plausibility of a reading; how it weighs those two properties; and when it finds a reading acceptable.

Occasional hints are given, like "The initial context usually consists of the proposition that has been processed most recently" (p. 1848). It never gets more specific than that, though. However, if these parameters were set, relevance theory could probably be (part of) an implementable parsing algorithm. It would differ from, say, Winograd's 1972 parser in that it uses relevance rather than truth as a measure of success.

A nice facet of this argument is that a relevance-theoretical account of metaphor doesn't have to treat all metaphors as dead, or all as live. It might be that some metaphors (e.g. "kick the bucket") simply contribute more to communication when they're processed as lexical items than when they're processed "deeply" (p. 1851).

Put in another way, relevance theory can pack the concept of conventionality into the concept of "early candidates." Since both speaker and hearer know this, they can use that common knowledge to optimize communication, i.e., they can choose to be conservative.

From Cognitive Metaphor Theory to Relevance Theory
Conversely, Tendahl and Gibbs argue that relevance theory can't quite cope with metaphors without help from the cognitive account (pp. 1847-48).

If I understand their point correctly, it is that internal search algorithm needs conceptual schemas like MIND AS CONTAINER and HEAD FOR MIND in order to arrive at the proper reading of He's full of ideas within reasonable time. In other words, if we don't have image schemas (or conceptual maps or conceptual blends or whatever), then we will not be sufficiently biased or guided our production of candidate readings.

Plus or minus the cognitive language, this seems fair. I would probably suggest that the effect has more to do with pattern recognition than with searching through a semantic space. But still, the observation that we need skewed priors seems valid.

"Science says"
There's a really annoying aspect of Tendahl and Gibbs' paper that I really need to comment upon. Consider these quotes:

[C]ognitive linguistic research has argued that many idioms have specific figurative meanings that are partly motivated by people’s active metaphorical knowledge.(p. 1849)

[T]here is a significant body of work suggesting that most idioms are not understood as dead metaphors, and have meanings that are understood in relation to active conceptual metaphors. (p. 1850)

Many studies have shown that conceptual metaphors can be active in the online interpretation of utterances and in the creation of meaning. (p. 1853)

None of these examples are followed by a reference, nor by an argument. Imagine the forest of skeptical tags that such language would solicit if I wrote like that on a Wikipedia page.

What's worse, the actual content of the claims is---to my knowledge---actually wrong. There is at least some evidence to that effect.