I am a hopeless handyman. I have poor attention to detail and lack patience. I am disorganised. When hanging a picture, rather than finding a hammer, I bash the tack in with whatever first comes to hand. Recent examples: A tin of Rawleigh's Medicated Ointment (reasonably effective), an ornamental porcelain donkey (bad - it didn't survive) and a book (a hard-backed edition of E. O. Wilson's Consilience: better than nothing, but now pocked with pinholes).
That we tend to do that sort of thing lies at the root of a big problem with the ideas inside Professor Wilson's book (just as well, therefore, it has some use for hammering in picture hooks). Using a familiar object to do an unfamiliar job is rather like coining a metaphor: It's a creative act. As well as being pragmatic, it has its advantages. (It must have some advantages - convenience; it overcomes the lack of botheredness to find the hammer - or you wouldn't do it). But while my tin of ointment (or ornamental donkey, for that matter) might not be conventional (and, in the donkey's case, might not work awfully well) it's not wrong. It is as good as the job it does. A "proper" tack hammer has been designed, to the exclusion of all other purposes, for hammering in tacks. You can imagine other objects being better or worse at functioning like hammers. Blu-tack, for example, would be hopeless. But not wrong. Just not much use.
And so it is with metaphors: they deliberately take a conventional concept and put it to work in a concept it wasn't designed for. As a result metaphorical meanings are different from literal meanings (in a manner of speaking) but no worse or better - while they might be more or less effective, effectiveness is in the eye of the beholder.
Often, a metaphor can more elegantly or succinctly some aspects of its "target" (which Julian Jaynes would call a "metaphrand") than a literal construction. "Love is a rose": I suppose you might take this to mean love is a delicate, beautiful, fragile, thing that can prick you if you aren't careful with it. Or that is is a soft, rich and complexly enfolded collection of different facets. These aren't mutually exclusive metaphors, but they're not entirely consistent either. Both of them make some sense, where a literal interpretation of "love is a rose" doesn't.
Now while I was bashing in my picture hook with Professor Wilson's book I got to thinking about what was inside his book, and how Professor Wilson's whole enterprise, his desired end state, is one which overlooks the metaphor. This is some irony as metaphors, and rich ones at that, are scattered prodigally around his text.
Professor Wilson, in Consilience, sees the possibility (not yet arrived) of a unified, unique, continuous, contiguous spectrum of knowledge, encompassing not merely the physics and the physical sciences, but all of the humanities too. In fact, I think he sees the necessity of it. Wilson is an unabashed reductionist. Wilson embraces a hierarchy of physical sciences (physics at the bottom, grounding everything else; Chemistry sitting atop it, Biology atop that, and so on. Higher sciences can be reduced to lower ones; all sciences are consistent with each other, and it is only a lack of data which prevents completion of the total blueprint of the physical universe. Thereafter the social sciences and even the arts will fall into a pre-ordained and logical place and will similarly be logical, consistent and unambiguously explicable. Wilson is excited by this idea (it horrifies me, personally), and sets out in his book to give it some intellectual underpinning.
Wilson is running before he can walk. Metaphor gets in the way - literally, and metaphorically. The same thing happened to Bertrand Russell following a similarly hubristic exercise restricted to the logical underpinnings of mathematics. In the infancy of the twentieth century Russell tried to chart the entirely cosmos of the mathematical universe by reference to a single, finite set of well-defined logical axioms. By limiting himself to numbers, Russell took up an easier challenge, you would think, than Wilson has. Mathematics was, Russell supposed, a closed logical system: finite, reducible and therefore well susceptible to his kind of enterprise.
But Russell failed to complete his mathematical globe. Russell didn't just not manage to get to all points in a large whole; he failed totally: his entire project, so pointed out a precocious young German chap by the name of Goedel, was logically flawed. Doomed.
The reason? Metaphor. Even though Russell had decreed some ad-hoc rules to guard against logical cul-de-sacs - for example, no item was allowed to be a member of its own set - it was possible to run mathematical operations by analogy - metaphorically, in other words, that could tell you things that a literal mathematical operation could not. And any ostensibly complete description of a language which forbade expressions such as "the set of all possible sets" was going to be practically useless anyway. There are some excellent accounts of Goedel's dramatic insight, Douglas Hofstadter's a particularly good one (though his ultimate conclusion seems wildly wrong).
When he does refer to metaphor, Wilson's is a rather unimaginative account: what he describes isn't metaphor so much as definitional drift occasioned by metaphor. To use one of his examples, by the time "plot" - a physical site and a building plan - came to mean "plot" - the narrative structure of a story - any figurative content in the expression had long since evaporated; seawater gone, a residue of salt.
Wilson's idea of a metaphor therefore is a dead one: these are the ones "normal scientists" like, of course, because dead metaphors can't get up and bite you by suggesting what you meant to say might be taken in a number of ways. If there were a substantive distinction between art and scientific literature - and like Wilson, but for radically different reasons, I'm inclined to think there isn't one - it might be found in the systematic exclusion of metaphor from scientific discourse. Science is about exactitude; consensus on a literal way of speaking enhances that end.
But at some cost, and not just in the notorious dullness of scientific literature. Literalness encourages and perhaps compels compliance with orthodoxy. Paul Feyerabend - another conspicuous absentee from Wilson's reading list - makes the inspired observation that scientific revolutions rely on inspired observations: a willingness to disregard the formal language of the discipline. If you stick rigidly to the rules of the prevailing scientific paradigm it is not possible to see, much less formulate, contradictions to it: Anything which looks like a contradiction, by the terms of the theory, must be explicable some other way (wind interference; malfunctioning equipment).
To find a new solution to a conundrum you are forced to use existing concepts in a new way. You can only do it by being creative with your language.