Eli Hirsch

Timothy Williamson has argued that the safety condition on knowledge places certain limits on iterations of knowledge. But at the same time, Williamson claims that interpersonal iterations of knowledge aren’t so restricted as to rule out ordinary cases. The present authors show that Williamson’s discussion misconstrues the challenge to iterated interpersonal knowledge. The proper argument against interpersonal iterations is rather what the authors call a third-person argument that does not share the major weaknesses of the argument Williamson considers. The challenge that the safety condition poses to interpersonal iterations of knowledge therefore seems robust, even in ordinary cases. But the authors also identify an underlying assumption that their argument relies on, and they show that Williamson’s original argument as well as his argument against intrapersonal iterations of knowledge rely on analogous assumptions. In assessing the extent of the clash between safety and iterated knowledge, the focus must be on the viability of these assumptions.

Two main claims are defended in this paper: first, that typical disputes in the literature about the ontology of physical objects are merely verbal; second, that the proper way to resolve these disputes is by appealing to common sense or ordinary language. A verbal dispute is characterized not in terms of private idiolects, but in terms of different linguistic communities representing different positions. If we imagine a community that makes Chisholm's mereological essentialist assertions, and another community that makes Lewis's four‐dimensionalist assertions, the members of each community speak the truth in their respective languages. This follows from an application of the principle of interpretive charity to the two communities.

In Eli Hirsch’s clever and careful Dividing Reality he asks us to consider several strange languages. For example, in the Gricular language there is no word that applies to all and only green things and none that applies to all and only circular things, but there are the three words “gricular,” which applies to anything that is either green or circular, “grincular,” which applies to anything that is either green or not circular, and “ngricular,” which applies to anything that is either circular or not green. Griculese is but one of the strange languages Hirsch explores, but they are all alike in having the same descriptive content as English—anything that can be said in English can be said in the strange languages, and vice versa. For instance, to say that something is green, we can say “it is both gricular and grincular.” Our strong intuition is that these languages are strange—irrational or worse. The challenge is to ground this intuition in some particular feature of the language that makes it defective. The problem is that there seems no good response to this challenge. Hirsch examines many proposals, and rejects every one. Thus he finds himself reaching a conclusion even he finds it difficult to accept. The disturbing conclusion, division relativism by title, is that our strong intuition is misguided—the “strange” languages are just as reasonable as English.

This is a strikingly original, rich, and trenchant study. Its point of departure is the notion of discrimination, which is shown to illuminate a range of topics in metaphysics and epistemology, including subjectivity, observationality, sorites paradoxes, and identity criteria. A central problem involves the phenomenal character of experience. We are intuitively tempted to say that character is subjective in the sense that distinct characters must be discriminable. This seems to imply that matching experiences--that is, experiences which are indiscriminable in character--must have the same character. We find familiar cases, however, in which the experiences x and y match, and the experiences y and z match, but x and z do not match. Williamson defends the subjectivity of character by arguing that a pair of characters may be indiscriminable as presented by one pair of experiences but discriminable as presented by another pair of experiences. Hence the indiscriminability of characters is indeed sufficient for their identity, which makes characters subjective, but the matching of experiences is not sufficient for the experiences' having the same character.