Prowling the Web for material on Nietzsche and the genetic fallacy, I stumbled across this passage from Merold Westphal, "Nietzsche as a Theological Resource," Modern Theology 13:2 (April 1997), p. 218:
Perspectivism need not be presented as an absolute truth; it can be
presented as an account of how reality looks from where one is
situated. It does not thereby cease to be of value. The account of
the game given by the winning coach cannot claim to be THE truth
about the game: other accounts must be taken into account,
including those from the losing coach, the players, the
referees,.... But that does not mean that we do not listen with
attention to what the winning coach has to say about the game.
Perspectivism is the proposition P: All truths are perspectival. Either (P) applies to itself or it does not. If the former, then one must conclude that (P) is itself perspectivally true. Call this perspectivized perspectivism (PP). If the latter, if (P) is not taken to apply to itself, then (P) is nonperspectivally true. Westphal mentions, but does not take, this tack, so I shall ignore it here. His position appears to be perspectivized perspectivism. Unfortunately, his example shows that he does not understand it. He confuses (PP) with a quite different doctrine that could be called alethic partialism.
What the latter says is that the whole truth about a subject cannot be captured from any one perspective. Take a quart of 10 W 30 motor oil. From the perspective of a salesman at an auto parts
store, it is a commodity from the sale of which he expects to make a profit. From the perspective of a motorist, it is a crankcase lubricant. From the perspective of a chemist, the oil's viscosity and other such attributes are salient. From the perspective of an eco-enthusiast, it is a potential pollutant of the ground water. And so on. But note that these partial truths add up to the whole truth about the oil. (By a 'partial truth' I do not mean a truth that is only partially true, but a truth that is wholly true, but captures only a part of the reality of what it is about.)
Alethic partialism sounds reasonable. But that is not what the perspectivized perspectivist is saying. What he is saying is that every truth is merely perspectivally true, and that this thesis itself is true only from his, and perhaps some (but not all) other, perspectives. Unfortunately, this allows a nonperspectivist such as your humble correspondent to say: "Fine! Truth is perspectival for you, Fritz, but for me it is absolute, and one of my absolute truths is that you are mistaken in your theory of truth." Clearly, the perspectivized perspectivist is in an uncomfortable position here. He wants to say something that is binding on all, but he cannot given the self-limiting nature of his position, a self-limitation demanded by logical consistency.
Pace Westphal, perspectivism is not "an account of how reality looks from where one is situated," but an account of the nature of truth, an account that implies that there is no reality. For truth is the truth of reality. A truth-bearer (a belief, say) is true just in case it corresponds to what is the case independently of anyone's beliefs, desires, or interests. To speak of truth as perspectival is to dissolve reality along with truth. From this one can see how obtuse Westphal's account of perspectivism his. He fails to grasp its radicality. And failing to grasp its radicality, he fails to appreciate its utter incoherence.