Comments on “The Epistemic Force of Experience”
I’m grateful to have a chance to comment on Susanna Schellenberg’s excellent paper. The paper nicely
connects issues in the metaphysics of perception with issues in its epistemology. Her main claims, in
brief, are these: 1) sensory states are systematically linked to what they are of in the good case; and 2)
because they are so linked, sensory states provide evidence for what they are of in the good case. The
first claim is metaphysical and the second draws epistemological consequences from it. I’ll start by
considering the metaphysical claim, turning to epistemological issues afterward.
According to Schellenberg, sensory states are determined (at least partially) by the set of perceptual
capacities employed in having them in the relevant sensory modality: same set of such capacities
employed, same sensory modality, same sensory states, at least other things equal. These perceptual
capacities are to be explained in terms of the good case: they are capacities to *perceive* particulars of
certain kinds, including physical objects, property instances, etc. Since the very same perceptual
capacities are at work in both the good and the bad cases it follows that there is an explanatory priority
of the good case over the bad case: the capacities exercised in both the good and bad case are
explained in terms of the good case, not in terms of the bad case. This explanatory priority derives from
a metaphysical priority of the good case over the bad case. One can possess and exercise the perceptual
capacities determinative of any sensory state only because one is the sort of being that can exercise
these capacities in the good case.
My main question about Schellenberg’s metaphysical picture is whether it can explain a key datum
about sensory experience. The datum is that (pardon the pun) is the sense-datum inference seems
phenomenologically plausible in the case of sensory experience. Whether in the good case or the bad
case or the weird case (which is unlike any good case – think fuzzy pink rats in the corner), it seems
phenomenologically plausible that there is something one is aware of that has the relevant sensible
feature. Even if I know I’m hallucinating, and so know there is no physical white cube before me, it can
seem plausible to me that I do “see” or “sense” something white. “There it is,” I might say, “I see its
whiteness.” No corresponding “thought”-datum inference is plausible. Suppose you thought, after
hearing the amazing Manti Teo story, “Lennay Kekua died tragically.” After you find out that there is no
such person as Lennay Kekua, you don’t find it at all plausible that you must have been thinking of
someone, though not a physical person, who did die tragically, or did have any properties.
How can Schellenberg’s capacities view explain this datum? I don’t think it suffices to point out that the
capacities at work in the bad case are explainable in success in the good case. Schellenberg, in places,
compares the capacity to single out objects in perception with the capacity to single out objects in
thought. I would think that if the good case is metaphysically prior to the bad with respect to perceptual
singlings out, this would be true of the capacity to refer in thought. So, when I think “Lennay Kekua died
tragically,” I employ capacities explainable in terms of successful cases of referring in thought. Still,
there is no temptation to find an “immediate” object of my thought that did die tragically. (The same
goes for other capacities individuated in terms of a good case. If I have the capacity to identify the
largest of groups of three fractions formed from numbers between 1 and 50, then when I use that
capacity to arrive at an incorrect identification (a bad case), it isn’t at all tempting to think there really
was something – not a number – which I did identify correctly as larger.)
In addition to this general concern, I had several questions of detail.
First, I wonder how exactly the argument for the metaphysical priority of the good over the bad case
goes. Suppose that in bad case I employ unsuccessfully the very same capacity I employ in the good
case, and that the nature of this capacity is explained in terms of achievements obtained only in the
good case (it’s a capacity to perceive white, for instance). How does it follow that one can employ such
a capacity in the bad case only in virtue of being the kind of being that could employ it in the good case –
as the metaphysical primacy thesis requires? Yes, the capacity is understood in terms of the good case.
But why must it also be true that I can employ it in a bad case only because I can employ it in a good
case? The question may not be of great moment for Schellenberg. I wonder whether her epistemic
conclusions would be jeopardized if the metaphysical priority claim was abandoned by the explanatory
priority claim retained.
Second, I am unsure how to understand the relevant perceptual capacities so that they are identical in
the good and bad cases. One would think, from reading up on the science of perception, that some of
the perceptual capacities relevant to experience include tracking of objects through eye saccades,
focusing of the lens, etc. But certain bad cases – e.g., the BIV case (or perhaps possible cases of TCM
stimulation) – do not involve the eyes or other sensory organs at all. Perhaps Schellenberg could say a
bit about what these capacities are and how they can be shared with a BIV.
Third, and relatedly, are these perceptual capacities object-dependent or object-independent? (Thanks
to Susanna Siegel for discussion on this.) I have a capacity to perceive this particular white cube. I also
have a capacity to perceive white cubes. Now, consider the BIV who isn’t seeing a white cube at all. Is
there some particular white cube such that the BIV is employing the capacity to see it? That seems
wrong. It must be an object-independent capacity, a capacity to perceive white cubes. (But don’t I in
the good case exercise the object-dependent capacity to perceive this white cube? Perhaps
Schellenberg will say that I exercise this capacity in a way that is not determinative of the sensory
experience, given the other capacities I exercise?) Next, consider properties. If the BIV has never
encountered a white physical object or white light, is it a good explanation of its sensory state to say
that it exercises the capacity to see white? Perhaps the BIV has the capacity to see white: if you
embody it appropriately, it will successfully exercise that capacity. But in its life of bad cases why think it
exercises that capacity unsuccessfully again and again rather than successfully exercising another
capacity, e.g., the capacity to visually represent that something is white? Of course, this threatens to
spoil the explanatory priority Schellenberg wants to make, for this capacity isn’t understood in terms of
achievements possible only in good cases.
Let me now turn to the epistemological consequences. Let’s assume Schellenberg is correct about her
metaphysical claims. She argues as follows: (i) if the metaphysical claims hold, then it is rational to
heed the testimony of sensory experience; and (ii) if it is rational to heed something, that thing is
evidence of what it is of in the good case; and therefore if the metaphysical claims hold, sensory
experience provides evidence of what it is of in the good case. I’ll grant (ii) and focus on (i).
Many functions are defined in terms of the good case without any sort of upshot for rational “heeding”.
The function of the heart is to pump blood, the function of the lens is to focus light on the retina. Of
course, in the case of sensory experience the function is to yield awareness of objects and properties.
So, the nature of these awarenesses in the good case must explain why perceptual capacities, unlike the
capacities of the heart and the lens, make us rational to heed their exercises in both the good and bad
cases. But how does the account go? What is there to heed? Think, first, about the good case. One
perceives an object and a property-instance. How can one heed this? We make progress in finding
something to heed in the good case if we say that in this case the object is perceived as having the
property. This might require turning away from an austere relationism that finds only particulars among
the objects of sensory awareness, but otherwise it seems promising. What about the bad case? What
is there to heed? One has a sensory experience, resulting from a capacity explainable in terms of
perceiving objects, properties, etc. What does this give one to heed, though? Schellenberg speaks of
the testimony of the senses. What is the testimony of a sensory experience in the bad case?
What we want, I think, is to capture the idea that sensory experience, in bad as well as good cases,
presents things as being a certain way. That’s something one could be rational to heed. I can see how a
metaphysical priority story of the good over the bad case could help us capture this idea, if we went for
a meatier common factor view, such as intentionalism. (In the bad case, in which I hallucinate a white
cube, we could then say that my experience has an intentional content, such as that is white or there is
something white here. Heeding such a content might amount to believing something is white.) But I
take it that for Schellenberg explaining the epistemic force of experience requires postulating no more
of a common factor than the involvement of the “same perceptual capacities.” I’m skeptical of this.
I’ll end with two further questions about the epistemic upshot of Schellenberg’s metaphysics.
First, suppose we explain what it is for sensory experience to present things as being certain ways. I’m
not sure how much it would matter to the epistemology of perception how sensory experience
managed to do this. That is, I’m not sure why the metaphysical grounding of this presentation would
matter epistemologically. Suppose a different kind of creature in a different possible world was
presented with things being certain ways, but through different capacities, not understood in
Schellenberg’s way, and not related to what they are of in the good case. I can’t see clearly why this
would matter epistemologically. Even if it turns out that it’s essential to sensory experience that it is
related to the good case in this way, I am unsure why this matters epistemologically more than which
brain state pain is matters to the ethical status of pain.
Second, I wonder how closely Schellenberg wants to tie sensory experiences with the capacities
exercised in them. Could the same sort of sensory experience exist without resulting from the relevant
capacities? If so, Swampman rears his head once again. Let Swampman have all the sensory capacities
and conceptual capacities we have, but suppose his first experiential state isn’t the exercise of such
capacities. Wouldn’t Swampman be rational to heed this first experience? If sensory experiences
cannot fail to be exercises of perceptual capacities, why is this? And, in any case, could something
introspectively indistinguishable from a sensory experience fail to be an exercise of such capacities? Let
Swampman start off with this sort of quasi-experience. Would this make an epistemic difference?
Thanks again, to Susanna Schellenberg and to Neuphi, for the chance to comment on such a challenging
and rewarding paper.
Matt McGrath