Background knowledge

The background knowledge strategy, or BKS, is a variation upon the

discriminatory capacities approach that appeals to the subject’s explicit or tacit knowledge of the correlation between their sensory impressions and object- or property-types. For example, a subject who has visually experienced a number of yellow-looking objects, the majority of which, upon inspection, in fact turned out to be yellow rather than merely appearing to be, could plausibly come to

know what it is to see an object as yellow.11 _{If these objects become their}

paradigms — or ‘samples’, to use Wittgenstein’s (1953: §16) terminology — of what it is to look yellow, then the subject can plausibly come to know that an

experience represents some novel object to be yellow by means of its similarity

to these paradigms. Such forms of background knowledge may be considered ‘external’ to perceptual experience in that the subject does not recognise an experience to represent yellow in virtue of that experience alone. Rather, by employing explicit (i.e. inferential) or tacit (non-inferential) knowledge of the link between subjective appearances and the objective characteristics of objects,

a subject can come to recognise their experience as representing that an object is

yellow as opposed to merely looking yellow or some other way.

To take a simple example, the yellowish, roundish appearance of a lemon may be taken to represent that there is something yellow, round, and so on in front of one because one knows (associates, has previous experience of, …)

objects with this appearance as being yellow, round, lemons, etc. Such

knowledge, if it can be described as such, will consist in associations between experiences of the relevant appearance types and the actual properties of objects which, upon further investigation, turned out to instantiate the properties that

one comes to associate with the corresponding appearances; i.e. being yellow,

round, a lemon, etc.12 _{Thus a form of Recognisability may be derived on the}

basis of the tacit knowledge of appearances.

By acquiring knowledge of the appearances of yellow objects, the subject thereby acquires the capacity to recognise not only yellow objects, but the

representation of yellow in perceptual experience. On this view, what privileges

being yellow as the content of such representation — as opposed to, say, being white and illuminated by yellow light — is its role in the relevant paradigm

cases. Typically, paradigm cases of yellow objects — a ripe lemon or banana, for

example — are in fact yellow and can be seen to be such under a wide variety of

environmental conditions.13 _{Thus whilst a white object, such as a white piece of}

chalk illuminated by yellow light, shares the same yellowish appearance and so ‘looks yellow’, it is not paradigmatic of that appearance. Consequently, on the present view, objects that look this way are represented in perceptual experience as being yellow in virtue of their possessing a similar appearance to (i.e. they

look like) certain paradigm objects that are yellow. That is, under BKS, just what it means to look yellow.

It is worth noting that something not unlike this kind of knowledge is present in Martin’s comparative analysis of looks-statements in the form of the

similarity function (4.3.1). This takes a predicate (e.g. is yellow) and a look,

yielding truth if and only if the latter is relevantly similar to the look of those objects that satisfy the predicate. Crucially, however, on Martin’s account this 12 _{Note that the application of such knowledge need not render access to representational} contents epistemically indirect since the relevant capacities may operate at a sub-personal level rather than involving conscious inference, at least once the learning phase is complete. 13 _{Note, however, that at least one paradigm case of a yellow object — namely, the sun — is} not in fact yellow, but white; it merely appears yellow due to the effect of atmospheric absorption (Wilk 2009).

need not be part of a psychological process that the subject goes through in identifying particular looks. Rather, it is part of the semantic analysis of looks- statements, and so not necessarily even implicitly known by the subject. If is therefore an important question for the BKS theorist whether subjects do in fact possess such knowledge of appearances and whether it is acquired or innate. If they do, then there seems to be no reason why this could not be applied at the level of recognising the content of perceptual experience on the basis of appearances.

According to BKS, then, a subject’s background knowledge of certain

paradigm cases of looks may be used to disambiguate p-representational

contents. However, in order for this to be more than a mere convention — i.e. a

way of reporting appearances, rather than constitutive of p-representation itself 

— it must be explained how this knowledge comes to figure in the content of

perceptual experience in the first place. For this to be the case, such knowledge

must in some sense be exercised by the perception of objects, whether

consciously or otherwise. The exercise of tacit or explicit background knowledge thus becomes equivalent to the possession of a conceptual, recognitional or discriminatory capacity for the relevant object- or property- type. When an object with the relevant appearance is perceived, this activates the subject’s background knowledge, causing the corresponding type to be

tokened as part of that experience’s representational content. BKS is therefore

effectively a special case of the discriminatory capacity strategy described below.