As I was reading his papers, I found that he quotes a fascinating passage about metaphor, which has much relevance with my article on metaphors and analogies.
So, below is a passage quoted at the beginning of Calvin's "The Trilogy of Homo seriatim:Language, Consciousness, and Music."
[All] thinking is metaphorical, except mathematical thinking.... What I am pointing out is that unless you are at home in the metaphor, unless you have had your proper poetical education in the metaphor, you are not safe anywhere. Because you are not at ease with figurative values: you don't know the metaphor in its strength and its weaknesses. You don't know how far you may expect to ride it and when it may break down with you. You are not safe in science; you are not safe in history....
All metaphor breaks down somewhere. That is the beauty of it. It is touch and go with the metaphor, and until you have lived with it long enough you don't know when it is going.the American poet Robert Frost
This passage serves as a kind of 'basso continuo' throughout the paper, in which he uses the metaphor of "Darwin Machines" to explain human cognition. The "Darwin Machines" have two steps of randomness and selection, and the machines go back and force between the two steps to evolve into something unexpectedly adaptive to the environment. Calvin's emphasis seems to be on randomness, which the economists' model of rational planning, for example, fail to recognize.
As Frost says, "all metaphor break down somewhere" , because metaphors do not represent 'truth.' However, good metaphors (or educated, aesthetic metaphors) introduce an exquisite degree of non-truth to extend the old concept elegantly. Metaphors are artistic introductions of randomness, the result of which is foreseen by a genius, but usually unknown to people until the metaphors go through the process of selection afterwards.
We need proper poetical education in the metaphor. (Or at least, I do.)