Abstract
Vague observational predicates like ‘red’ and ‘loud’ are associated with at least two distinctive philosophical problems. First, these words appear to generate the most intractable form of the sorites paradox because they permit the construction of sorites series in which neighboring items are indiscriminable, not just incrementally different, on the relevant dimension. While it is at least non-incredible that incrementally different in a sorites series are category-different, the idea that indiscriminable items could be category-different seems beyond the pale. Second, the nontransitivity of the observational indiscriminability relation threatens the coherence of the notion of determinate observational qualities such as shades of color and loudness levels. In this chapter I examine these two problems and discuss some experimental results that shed new light on them.
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Notes
- 1.
The term ‘match’ is used in various ways in the literature. Nelson Goodman, whose use of it is perhaps most familiar, seems to conceive of matching as an invariant relation of appearing (e.g., looking) the same that holds between two stimuli or objects. Peacocke appears to follow suit. Since I don’t believe that such a relation can be instantiated in human perceptual experience, I will not use the term here. See pp. 9–10 above.
- 2.
- 3.
For present purposes I am going to use the terms ‘appears Φ’ (e.g., ‘looks Φ’) and ‘is judged Φ’ interchangeably. In particular, I will speak indifferently of objects appearing the same or different and objects being judged the same or different in a same/different task. In talking this way I am of course ignoring many important questions about the relationships among experience, judgment, and verbal report; but I think we can safely set those questions aside here. See Raffman, 2000 for discussion.
- 4.
More precisely, signal detection theory computes the ratio of hits to false alarms.
- 5.
Philosophers may find this surprising. Wright speaks for many when he considers the possibility that
between [any] pair of [stimuli] discriminable in respect of Ф lies a stage discriminable from them both and from any stage outside the region which they flank. We have to suppose that we have in this sense infinite powers of discrimination…, that we can always directly discern some distinction more minute than any discerned so far….[We may naturally suppose] that this is not so (1976, 346).
- 6.
Hellie (2005) claims that “noise is a central source of the non-transitivity of perceptual indiscriminability even under optimal, normal circumstances. Noise blurs subtle differences; for sufficiently similar colors, this yields uncertainty whether they are distinct. If all signals were clean, perhaps only identical colors would be perceptually indiscriminable” (2005, 506). The idea seems to be that in the absence of noise, we might be indefinitely sensitive discriminators even “in the short run”. This hypothesis is far more radical than the Hardin-Swets view.
- 7.
See again note 3.
- 8.
See also Dummett, 1975.
- 9.
I-series are also thought to give rise to sorites paradoxes for determinate quality predicates such as ‘red19’ and ‘loud4’. For example, suppose that in Burns’s Armstrong triad, a is red19 and c is red20. The following argument then seems valid:
(1)a is red19.
(2)Anything that is indiscriminable from something that is red19 is itself red19.
(3)Therefore c is red19.
- 10.
We had established the thresholds of our subjects in an earlier pilot experiment, requiring correct detection on 75% of trials.
- 11.
These identical pairs were used in “catch” trials that tested for false alarms, i.e., judgments of “different” made about identical stimuli.
- 12.
For ease of discussion here I use the term ‘wavelength’, but it is strictly speaking incorrect. Rather, the stimuli were mixtures of broadband lights, and neither the primaries nor the mixtures have a defined wavelength.
- 13.
My own view is that colors – both determinate shades and broader determinables like ‘magenta’ and ‘red’ – are rather like hats that visible objects can put on and take off depending upon a variety of factors such as viewing context and the state of the viewer’s visual system. I can’t say more here, however.
- 14.
In conversation. Glenn Fry was Regents Professor and Director of the School of Optometry at Ohio State University.
- 15.
See Raffman 2010 (ms), especially Chapter 4, for extended discussion.
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Raffman, D. (2011). Vagueness and Observationality. In: Ronzitti, G. (eds) Vagueness: A Guide. Logic, Epistemology, and the Unity of Science, vol 19. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-0375-9_5
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