Problem of Known Illusion and the Resemblance of Experience to Reality
The Problem of
Known Illusion and the Resemblance of Experience to Reality
If John Locke (1690/1975) is right, color might not be a feature of things
as they are in themselves, but shape
is a feature of those things. If I see a
cube in normal conditions and rightly judge that it is a cube, then by gum
there really is a mind-independent cubical thing out there, the shape of which
in some important way resembles my
experience of its shape. If Immanuel
Kant (1781/1787/1929) is right, then John Locke is wrong about this. Things in themselves aren’t cubical – or at
least we have no good reason to think they are cubical. They’re not laid out in space. There’s nothing independent of the human mind
that has cubical properties that resemble the properties of my visual
experience of cubes.
I’d like to know if Locke is right or
Kant is right. Do things as they are in
themselves have shapes that resemble, in some important way, my experience of those
shapes, or not? Are things, really, like this [here I gesture, through an act of
attention, at my own visual experience]? Or is this
just a sheen, a convenient interface experience, a human
construction atop a radically different reality?
This might seem a hard question to
I don’t have an answer. But I do have a thought about a way in. My thought is this. Suppose it’s the case that there are multiple
different ways of veridically visually experiencing
the same object, so that we can’t say “this way is right and this way is wrong”
or “this way is preferred over this other way”.
And then suppose further that sometimes it is also the case that there
is no good reason to think that one of those two experiences more closely
resembles how the experienced object is in itself. From these suppositions, it would seem to
follow that there’s a kind of looseness
between the features of experience and the features of things in
themselves. Things in themselves might
be more like this or they might be
more like that. They might more closely resemble experience A
or they might more closely resemble experience B. Or they might really resemble neither
experience very well. Thus, we get at
least some bracketing parameters: We can no longer say we know that things in
themselves are like this, at least in
whatever respect this differs from that – a miniature Kantian victory over
To clarify what I have in mind here, I
will focus on two examples.
2. “Objects in Mirror Are Closer Than They Appear”.
According to the United States Code of
Federal Regulations, Title 49, Chapter 5, §571.111, S5.4.2, pertaining to
convex mirrors on passenger vehicles:
Each convex mirror shall
have permanently and indelibly marked at the lower edge of the mirror’s
reflective surface, in letters not less than 4.8 mm nor
more than 6.4 mm high the words “Objects in Mirror Are Closer Than They Appear”
(GPO.gov, accessed July 13, 2011).
Figure 1: Objects in
mirror are closer than they appear
here’s a picture that contrasts how things look in a convex mirror with how
they look in a flat mirror:
Figure 2: The view in
flat (on left) vs. convex (on right) driver’s side mirrors
image detail from Wierwille et al. 2008
consider: Are objects in the convex mirror
closer than they appear?
Here are three possible answers:
(1.) Why yes, they are!
(2.) No, objects in the mirror aren’t
closer than they appear; but that’s because rather than being closer than they
appear they are larger than they
appear. The convex mirror distorts size rather than distance.
(3.) No, objects in the mirror aren’t
closer than they appear; nor are they larger than they appear; if you’re a
skilled driver, the car behind you, as seen with the aid of the convex
passenger-side mirror, is just where it looks to be and just the size it looks
Answer (3) is the one I’m drawn to. One reason to favor the answer (3) is that
there seem to be no good grounds to privilege saying that objects are closer than they appear in the convex
mirror over saying that they are larger
than they appear. It could be a
3-foot-tall car 30 feet away or a 6-foot-tall car 60 feet away. Nothing obvious about its appearance, as
distorted by the mirror, decides between these two interpretations. But it also seems odd to just split the
difference and say that it looks 4 1/2 feet tall and 45 feet away. If answers (1) and (2) each problematize each other, that might
give us reason to favor answer (3). Another
reason to favor the answer (3) is that skilled drivers are undeceived. Decades of auto safety research shows that practiced
drivers do not misjudge the distance of cars in convex passenger-side
mirrors. They don’t misjudge when they
are asked oral questions about the distance, nor do they misjudge when they
make lane-shifting decisions in actual driving.
Instead, they seem to skillfully and spontaneously use the mirror
accurately to gauge the real distance of the cars behind them (e.g., de Vos 2000; Wierwille et al. 2008). This is not by itself a compelling reason to
favor answer (3); presumably, anyone generally predisposed to think that the
objects in the mirror are closer than they appear will allow that people
familiar enough with the illusion might be entirely undeceived by it. But I hope you’ll agree that there’s
something a bit happier about a position that avoids the proliferation of such
undeceiving illusions, if an alternative theory is available.
A third kind of evidence for my preferred
answer is introspective: Get in a car.
Drive. Think about how the cars
behind you look, both in the driver’s-side and in the
passenger’s-side mirrors. Try adjusting
the two mirrors so that they both point at the same car behind you when your
head is centrally positioned in the cabin.
Does the car look closer when your eyes are pointing toward the flat
driver’s-side mirror than when they’re pointing toward the convex
passenger’s-side mirror? Based on my own
messing around, I’m inclined to say no, the cars look the same distance in the
two mirrors. I’m inclined toward what I
will call the Multiple Veridicalities view.
There’s more than one way in which a car can look like it is 6 feet tall
and 60 feet behind you. There’s a
flat-driver’s-side mirror way and there’s a convex passenger’s-side-mirror
way. And both ways are equally
veridical. Flat mirrors aren’t
inherently more veridical; convex mirrors aren’t inherently distortive. It’s a matter of what we’re used to.
Anyhow, that’s the view I’m inclined
toward, partly on introspective grounds, partly on grounds of theoretical
elegance. Now if it can be sustained, we
can consider other cases of multiple veridicalities too: how things look through
my new progressive-lens spectacles vs. how things look through my older
single-correction prescription glasses; how the moon looks when it’s near the
horizon vs. how it looks at zenith; how the oar looks when partly immersed in
water vs. how it looks in plain air. Is
there more than one way in which the oar can “look straight”?
I do have a bit of trouble in good
conscience acquiescing to the Multiple Veridicalities view in the oar
case. What I’d like to be able to say is that to the truly skilled oar-in-water
perceiver, the oar partly submerged in water no longer looks crooked. It looks straight. It looks just the way a straight oar should look when partly submerged in
water. There are now just two different
and equally good ways in which an oar can look straight – the plain air way and
the half-submerged way, and neither experience more closely resembles the
straightness of the oar as it is in itself.
Maybe if we’re inclined to think otherwise, that’s only an accident of
what is more common in our experience and what is less
common. If there were, perhaps, a world
in which every straight thing were always seen half-submerged in a refracting
medium, we would say “that looks straight, straight, straight!” and when
finally for the first time an oar was pulled into plain air we would say “oh,
how crooked it looks; what an illusion!”
As I said, that’s what I’d like
to say. It would be cool if it were
true. But I’m not sure that I know that
If we treat the convex mirror case as
I’d like to, then it seems we can construct a garden path to the oar case, via
intermediate cases such as hypothetical windshields that contain a refractive
portion to allow a broader field of view, skilled spearfishers
who never aim wrong, corrective eyeglasses that habitually slip down the nose,
head-mounted cameras, etc. We could
consider jewelers with fish-eye lenses surgically installed, gods whose eyes
are giant spheres in which we dwell, all kinds of hypothetical creatures to
whom a square object might look very different than it looks to us. If would be delightful if we could treat all
these cases in a unified way.
3. Inverting Lenses.
Let’s consider a famous case from the
history of psychology, the case of the inverting lenses.
Inverting lenses were first tried by
George Stratton in the late 19th century (1896, 1897a-c). Stratton covered one eye and then presented
to the other eye a field of view rotated 180 degrees, so that top was bottom
and right was left. In his primary experiment,
he wore this lens for the bulk of the day over the course of eight days, and he
gives detailed introspective reports about his experience. Stratton adapted to his inverting lenses, as do
others who wear the lenses for an extended period. But what does adapting consist in?
The simplest possibility to
conceptualize, perhaps, is this: After adaptation, everything goes back to
looking just the way it did before one donned the inverting lens. Let’s say that pre-experiment one looks out
at the world – at, say, a lamp. Let’s
call the way things look, the way the lamp looks, before you put on the lens, “teavy”. Now you put
on the lens and everything seems to have rotated 180 degrees. Let’s call that visual experience, that way
the lamp looks to you now, “toovy”. Over the course of adaptation, then, what
happens on this view is that things go back – perhaps at first slowly,
unstably, and disjointedly – to looking “teavy”. After adaptation they look the same way they
would have looked if you had never donned the inverting lens in the first place. This is the way adaptation to inverting
lenses is often described, for example by James Taylor in his influential 1962
book and by Susan Hurley and Alva Noë in their 2003
article on the topic.
But there’s another possibility – I
think a more interesting one. That’s the
possibility that things remain toovy throughout. They never go back to teavy. But you get
used to their looking toovy, so that you lose the
normative sense that that’s a wrong
or misleading way for things to look.
The lamp no longer looks “upside-down” in the normative sense of looking
like the wrong side is on top; but it retains its “upside-down” look in the
non-normative sense that the visual experience is the reverse of what it was
before you put on the inverting lenses.
To the adapted mind, there would now be two ways in which a lamp might
look to be right-side up – the pre-lens teavy way and
the post-lens toovy way. (Maybe toovy
changes, too, as one accommodates – becoming toovy-prime,
say, more richly and accurately layered with meaning and affordances; the
important thing here is that it doesn’t go back to teavy.) Just like with the convex mirror there would
be multiple veridicalities – two ways of something’s looking to have the same
objective set of spatial properties and position and orientation relative to
Now it’s an empirical question whether
the Multiple Veridicalities view is correct about inverting lenses or whether
things really do just go back to looking teavy after
adaptation. And it’s a tricky empirical question – one that
requires I think a fairly subtle sense of what the possibilities are, a subtle
sense of the different things one might mean by saying that something “looks
like it is to the right or to the left” or “upside-down”. As one might expect, the introspective
reports of people who have tried inverting lenses are not entirely consistent
or unequivocal. However, my assessment
of the evidence is that the experimenters with the best nose for this sort of
nuance – Stratton himself and then later Charles Harris (1965, 1980), favor the
Multiple Veridicalities view. (See also Linden, Hallenbach, Heinecke, Singer, and Goebel 1999; Klein 2007). If so, there’s more than one way for a lamp
to look right-side up.
I look out now upon the world; I imagine
looking out upon it, just as veridically, through a
fish-eye lens; I imagine looking out upon it, just as veridically,
through increasingly weird assemblies that I would have said, the first time I
gazed through them, made some distant things too large and some nearby things
too small, that presented twists and gaps – maybe even that doubled some things
while keeping others single – and to which I grow skillfully accustomed. I try to imagine my phenomenology not shifting
back to what it was before, but remaining very different, while losing its
sense of wrongness, so that I am no longer tempted to say that things in
themselves are more like this than
like that. I imagine extending this exercise to my other
I’m not sure how far I can push this way
of thinking, but the farther I can push it, the looser the relationship would
seem to be between my experience of things and things as they are in
themselves. My hunch is that numerosity and contiguity are the anti-Kantian’s best hope
for resemblance between things in themselves and one’s experience of them –
that a “toovy” (or “toovy-prime”)
visual experience from a visual array pieced-up and multiplied would lack some
dimension of resemblance to things in themselves that ordinary visual
experience has and that is still preserved in inversions and convex
Maybe Kant or some other philosopher has
presented a sound a priori argument that our experiences can’t really resemble
things as they are in themselves in any useful sense of “resemble”. I am exploring, instead, an empirical path
that might lead at least partway toward the Kantian conclusion, grounded on
introspective observation of variability among different seemingly equally
veridical sensory experiences.
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 For helpful conversation
during the course of writing, thanks to Scott Bakker, Robert Briscoe, Brit
Brogaard, David Chalmers, Louie Favela, Jack Lyons, Farid
Masrour, David Papineau,
Kevin Reuter, Susanna Siegel, Houston Smit, Maja
Spener, Nathan Westbrook, commenters on relevant
posts at The Splintered Mind, and audiences at University of Missouri-St.
Louis, and the Philosophy of Science Association.