Abstract
A very natural view about perceptual knowledge is articulated, one on which perceptual knowledge is closely related to perceptual discrimination, and which fits well with a relevant alternatives account of knowledge. It is shown that this kind of proposal faces a problem (the closure problem), and various options for resolving this difficulty are explored. In light of this discussion, a two-tiered relevant alternatives account of perceptual knowledge is offered which avoids the closure problem. It is further shown how this proposal can: (1) accommodate our intuitions about perceptual knowledge and perceptual discrimination in terms of the notion of primary relevance, (2) give an account of how alternatives can be rationally excluded without appeal to perceptual discrimination in terms of the notion of secondary relevance, and (3) deal with the problem posed by inverted Gettier cases, and hence explain what it means to rationally exclude alternatives which are of secondary relevance.
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Notes
The zebra/cleverly disguised mule example is due to Dretske (1970). Note that not all perceptual knowledge is knowledge of objects—for example, some perceptual knowledge is of distances. We take it, however, that perceptual knowledge is paradigmatically about objects, and so in order to simplify matters in what follows we will set these other types of perceptual knowledge to one side. (If one prefers, then one can think of the type of perceptual knowledge at issue as specifically objectual perceptual knowledge). Moreover, in order to keep matters as simple as possible, in what follows we will be focussing on cases of perceptual knowledge where there is a single object at issue.
Notice that we are understanding the ordering of possible worlds in the standard way in terms of their similarity to the actual world. See especially Stalnaker (1968) and Lewis (1973). A different way of understanding relevance is in probabilistic terms, such that what makes an alternative irrelevant is the fact that it concerns low-probability possibilities. Although the difference between the two views is not particularly important here (because, for the most part, low probability possibilities are far-off possibilities, and high probability possibilities are close possibilities), we favour the first sort of proposal because of the fact that low probability events can occur in near-by possible worlds (think, for example, of lottery wins). In such cases, we maintain that the modal nearness of the possibility will make it relevant even despite the fact that it is a low probability event. For a defence of a version of the probabilistic account, see Cohen (1988).
Notice as well that this account of perceptual knowledge is very anti-intellectualist, which might also be thought to be an advantage of the proposal. For example, a small child may lack the concept of a horse and yet, because she can nevertheless perceptually discriminate between zebras and horses, she can still come to know that what she is looking at is a zebra.
This is a different—and, we think, more plausible—way of understanding the closure principle to how Dretske (1970; cf. Dretske 2005a) himself understands it, though nothing hangs on this difference here. This formulation of the closure principle is essentially that offered by Williamson (2000, 117) and Hawthorne (2005, 29). For the most recent critical discussion of the closure principle, see the exchange between Dretske (2005a, b) and Hawthorne (2005).
What is common to these views is a commitment to something like the sensitivity principle as a condition on knowledge: roughly, that one’s belief should be such that, had what one believed not been true, one would not have believed it. One key problem that faces such proposals is that once the sensitivity principle is expressed in the right way, then it is no longer obvious that it generates the kinds of counterexamples to the closure principle that it was designed to explain, and nor is it obvious that it is authentic to the core relevant alternatives intuition that motivated the rejection of this principle in the first place. On the first point, see Williams (1991, Chap. 9) and Black (2002). On the second point, see Pritchard (2002, 2005, Chaps. 2–3). There are lots of other objections that have been levelled against sensitivity-based views, of course. For a recent statement of one such objection, see Sosa (1999). For an overview the literature on modal conditions on knowledge, see Pritchard (2008b).
Notice that in spelling out the closure problem we have set to one side radical sceptical alternatives. This is because error-possibilities of this kind raise special problems of their own, and hence are best discussed in their own right separately.
Indeed, see Pritchard (2012) for a recent articulation and defence of epistemological disjunctivism.
See Weber (1997) for further discussion of this phenomenon.
It is an interesting question why this possibility has been largely overlooked in this debate. See Pritchard (2010, §5) for a discussion of some possible explanations.
One very natural way to think of the requirement that S be able to distinguish As from (primary-relevant) B-alternatives will be in terms of a simple subjunctive conditional analysis—viz., S is able to distinguish As from (primary-relevant) Bs in conditions C if and only if S would correctly distinguish the two, if C were the case (Lewis 1997; Choi and Fara 2014). On the standard semantics for subjunctive conditionals, this would mean that S would distinguish As from (primary-relevant) Bs in conditions C provided S distinguishes As from (primary-relevant) Bs in all close C-worlds. Of course, any more detailed proposal will have to, à la Choi (2008), include some kind of ‘anti-disrupter’ clause to deal with finks, masks and mimics. (See here also Alfano 2014 for a helpful discussion). While this issue of how to refine something like this subjunctive conditional analysis is a point of contention amongst proponents of relevant alternatives theories, we will remain neutral on the matter of how best to understand the right way to refine the discrimination requirement.
See Pritchard (2010) for an earlier presentation of a two-tiered relevant alternatives account of perceptual knowledge along these general lines.
We are using awareness in broadly the same way as access internalists about epistemic justification use the term when specifying, as a condition on epistemic justification, that a subject ‘be aware’ of the relevant justifiers for the target belief. Whilst some access internalists simply take the matter of what constitutes awareness at face value, there are some attempts to cash the condition out. As a (relatively uncontroversial) first pass at doing so, consider Alston’s (1986, 186) proposal that S is aware of p when p is something ‘that falls within the subject’s ken, something of which she has taken note.’ Of course, Alston’s somewhat generic view invites the question of what it is in virtue of which S counts as taking note of p, when S is aware of p. On this point, Bergmann has remarked that:
All such awareness will […] involve conceiving of the justification-contributor that is the object of awareness as being in some way relevant to the justification or truth of the belief. (Bergmann 2006, 13)
This suggestion is plausible; correspondingly, and recasting Bergmann’s insight, it’s plausible to suppose that one is aware of an alternative, qua alternative, only when one conceives of the alternative as being incompatible with the target proposition. Accordingly, and intuitively, one does not count as being ‘aware’ of the alternative, qua alternative, when one merely considers the alternative without appreciating it, or conceiving of it, as incompatible with the target proposition.
It is tempting to consider how the notion of secondary relevance might be applicable in epistemology more generally, beyond just perceptual cases. For instance, consider an auditory case, where an individual, Opie, is listening to a vocal operatic performance. Opie, an amateur opera enthusiast, thinks that he is listening to a baritone, though he suddenly subsequently entertains the matter of whether one of the performers that evening could be a countertenor. Plausibly, we might say that—and in a fashion relevantly analogous to what we say in the perceptual case—that the proposition that the singer is a countertenor now becomes secondary relevant for Opie, and that he must accordingly be able to rationally dismiss this (secondary-relevant) alternative in order to know that the present vocal operatic performance is by a baritone. (This is so, we suspect, even if countertenors don’t ordinarily perform in the particular venue Opie is visiting). We find this suggestion to be plausible, and in fact, it may be that a relevant alternatives account of perceptual knowledge will bear close resemblances to a plausible relevant alternatives account of auditory knowledge. It is beyond the scope of the present proposal to trace out to what extent the ‘second tier’ of our relevant alternatives view is going to be applicable outside the arena of perception, which is our central focus. That said, however, we do want to highlight one point of contact between secondary relevance and epistemology more generally. On the proposal offered here, we’ve submitted that what matters for secondary relevance is either that the subject is aware of the alternative qua alternative or that this is an alternative that she ought to be aware of. The latter element of the two-tier view might be best served by adverting to a more general account of normative defeaters, one not restricted to perceptual cases. See here Goldberg (2015).
The claim that one’s knowledge can be undermined by defeaters that one ought to be aware of is widely held. Lackey (2010, 317), for example, both endorses this view and also credits it to a wide range of other epistemologists.
This characterization of Gettier cases is not entirely right, at least unless Schaffer is referring only to Gettier-style cases in which the belief in question is inferential (plausibly, there are Gettier-style cases where the target belief is acquired non-inferentially).
In this kind of conversational context, it’s reasonable to take it that, from Jonathan’s perspective, the alternative is being rationally raised, though for our purposes nothing turns on this. Incidentally, note that Schaffer sets up his ORNITHOLOGY case in terms of a choice between only two alternatives: goldfinch or canary. Knowing that something is a goldfinch rather than a canary is not, however, necessarily the same thing as knowing that something is a goldfinch simpliciter (e.g., because while goldfinches are easy to tell apart from canaries in the relevant environment, there are other things in the environment that look just like goldfinches). Since Schaffer (e.g., 2005) advocates epistemic contrastivism, however, he rejects the idea of knowledge simpliciter altogether, but we do not need to get into these issues here. For our purposes, then, we will treat black wings as in general good indications of a goldfinch, and not merely as a good indication that something is a goldfinch rather than a canary.
This point applies in equal measure to cases where the secondary relevant alternative is rationally motivated and cases where it is not. The only difference is that in the former case what is under discussion will be one’s epistemic position with respect to a more demanding variety of favouring epistemic support than in the latter case. We will be setting this difference to one side in what follows.
Of course, Jonathan would in this case say that he knew, but what interests us is whether he actually knows and not what he would report in this regard. (We mention this point because in ORNITHOLOGY Schaffer is explicitly concerned with whether the subject would say that he had knowledge).
This point should remind us of Carroll’s (1895) parable of Achilles and the Tortoise. Here, for example, is Ryle’s spin on this parable:
A pupil fails to follow an argument. He understands the premises and he understands the conclusion. But he fails to see that the conclusion follows from the premises. The teacher thinks him rather dull but tries to help. So he tells him that there is an ulterior proposition which he has not considered, namely, that if these premises are true, the conclusion is true. The pupil understands this and dutifully recites it alongside the premises, and still fails to see that the conclusion follows from the premises even when accompanied by the assertion that these premises entail this conclusion. So a second hypothetical proposition is added to his store; namely, that the conclusion is true if the premises are true as well as the first hypothetical proposition that if the premises are true the conclusion is true. And still the pupil fails to see. And so on for ever. He accepts rules in theory but this does not force him to apply them in practice. He considers reasons, but he fails to reason. (Ryle 1945, 5–6)
Ryle’s own view is that what this shows is that the pupil lacks a certain ability, an ability such that: for any proposition p he comes to believe, it will still remain an open question whether S has the ability in question—in this case, the ability to draw an inference. Ryle himself thought that this indicates that knowledge-how (in the sense of knowing how to draw an inference) is not merely knowledge-that. More generally, though, the resemblance to the case at issue for us is this: in both cases, one seems hard pressed to explain how the ability to do something (either, to draw an inference, or to appreciate how one’s evidence entitles one to rationally dismiss an alternative and so know a proposition) will ever be entailed by the mere possession of (and belief in) further propositions (evidence). Note however that Ryle’s own gloss on the Carroll case is but one way of taking a lesson from the Carroll case. See Engel (2007) for some discussion of other potential lessons (which won’t concern us here).
This kind of proposal is popular in contemporary philosophy of science. See, for example, Lipton (2004) and Kitcher (2002). See also Grimm (2014). While Grimm agrees with Lipton and Kitcher that one understands why something is the case so long as one possesses knowledge of the relevant causes, Grimm parts company with Lipton and Kitcher in that he rejects a propositional reading of the knowledge in question. See Pritchard (2014) for a criticism of Grimm’s proposal.
Plausibly, even a child could acquire such knowledge, at least provided the child can be said to have a conception of the truth-conditions of the sentence, such that she counts as knowing what the sentence in question means.
Note that any plausible factivity constraint on understanding-why precludes that S can understand why φ so long as S appreciates how any old incorrect explanans stands in relation to a given explanandum. For instance, even though one might think that combustion is explained by phlogiston principles, S fails to understand why the combustion occurred, and even if phlogistion principles stand in a kind of reflective equilibrium with the observed data. Likewise, one fails to understand why some item of evidence excludes an alternative if such an explanation is likewise riddled with falsehoods. In short, one might achieve an intelligible picture of the event in question, without achieving understanding-why it occurred.
We say ‘roughly’ because this account needs to be refined in at least two ways. First, one will need to restrict this account of cognitive achievements to those which involve ‘manifestations’ of cognitive agency (see Sosa 2007, passim; Turri 2011). For example, both the fact that Madonna has produced lots of records and the fact that she is rich are primarily creditable to her musical abilities (and thus ‘musical agency’), in the sense that the latter is (let us grant) in both cases an overarching part of the causal explanation for the former. But only the record constitute a manifestation of her musical ability—the wealth is rather a side-effect of this manifestation of ability. In the same way, what we are interested in here are not simply cases where cognitive success is primarily creditable to one’s cognitive abilities (and thus cognitive agency), but rather those cases where in addition the cognitive success involves a manifestation of one’s cognitive abilities. A second restriction needed to this account of cognitive achievement concerns a specification that the cognitive abilities in question need to be the ones salient to this cognitive success. In order to keep our discussion manageable, we will be setting both conditions to one side in what follows. For further discussion of cognitive achievements, see Pritchard et al. (2010, Chaps. 1–4).
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Acknowledgments
We are grateful to James Genone and Katherin Glüer for detailed comments on an earlier version of this paper.
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Carter, J.A., Pritchard, D. Perceptual knowledge and relevant alternatives. Philos Stud 173, 969–990 (2016). https://doi.org/10.1007/s11098-015-0533-y
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DOI: https://doi.org/10.1007/s11098-015-0533-y