It Must be Human
You will search in vain for voices in The Oxford Handbook of Contemporary Philosophy. Pick a passage from any of its 29 entries; you will not know who is writing. Anatoly Karpov, the Soviet chess master, once boasted: "Style? I have no style." Philosophers take equal pride nowadays in an absence of rhetorical effect. Arguments, circulated and refined like a chess opening 12 or 15 moves deep, are their stock in trade.
This striking passage appeared in a recent review in the Economist, at roughly the same time as a New Yorker article, "Your Move", about the triumph of the chess computer. This conjunction triggered the oppressive image of the philosophy computer, able to defeat even the best human intellects. (Deep Thought, perhaps?)
Stylistic variation may be lacking in the Oxford Handbook, but I think it can be found in recent work. Davidson, Kripke, Lewis, Rawls: each has a distinctive presence in his work, and the same could be said of many others. (This is especially true of some philosophers with whom I am obsessed, but about whom it is not easy to write: Wittgenstein, Murdoch, Stanley Cavell.)
In any case, the real fear is not that philosophical writing is unpoetic, but that this is true of philosophical ideas: "It is as if / We had come to the end of imagination / Inanimate in an inert savoir."
Wallace Stevens (who wrote those words) addressed our question in an unpublished lecture, "A Collect of Philosophy", the theme of which is that the concepts of philosophy are, or can be, poetic. His chief example of this is the infinity of the world. Other proposals are found to be less successful. Thus Leibniz' monadology is "the disappointing creation of a poet manqué [...] a poet without flash."
The highlight of "Collect" is a lovely compendium of condensed philosophers sent to Stevens by Paul Weiss:
Plato: all things participate in the good; all beings love what they do not have, to wit, the good. Aristotle: all beings strive to realize their peculiar goods, already exemplified in some being somewhere in the natural world. St. Francis and St. Bonaventure: all beings have at least a trace of God in them. St. Thomas Aquinas: all existence is owed to God. Descartes: all bodies are machines. Leibniz: the world is at once the best and most rational of worlds; all the things we know in experience are combinations of spirits. Spinoza: all things happen by necessity; all things are in God. Kant: to be free is to be moral, and to be moral is to be free.
Can philosophical ideas still be poetic? The idea, for instance, of numberless worlds, each as real as this one, as concrete, in which everything possible is realized? Or must we fall back, at last, on an argument that ends the poem I quoted above?
Yet the absence of imagination had
Itself to be imagined. The great pond,
The plain sense of it, without reflections, leaves,
Mud, water like dirty glass, expressing silence
Of a sort, silence of a rat come out to see,
The great pond and its waste of the lilies, all this
Had to be imagined as an inevitable knowledge,
Required, as a necessity requires.