Illusion is therefore compatible with an absence of false beliefs (about
the illusion). Another way to put this would be to say that the victim
of the illusion need not be deceived: hence, spectators may be‘victims of
illusion’, even although they know the truth about what they are seeing.
Of course, that doesn’t mean that there isnoconnection between illusion
and false belief. It’s just that a necessary condition for X being an illusion
cannot be the existence of a false belief exactly when I look at X.
If we all agree that optical illusions are illusions, then an obvious
question to ask would be:‘are there optical illusions at the theatre?’The
answer is that sometimes there are, notably as a feature of set design. From
the perspective of the audience member, the‘room’on stage can look a cer-
tain way (say, symmetric); on closer inspection, it turns out to be completely
different (say, asymmetric). But, of course, plenty of theatre does not
make use of optical illusions in set design, so it wouldn’t be right to say
that optical illusions are a systematic or fundamental feature of theatre.
The most we can say is that they may well be employed and (from the
perspective of the audience) it can be hard to tell.
General sensory illusion
Perhaps the Fraser Spiral and other optical illusions just form a subset of
an‘enriched’or broader kind of sensory illusion, which is a much more
widespread feature of theatre?^43 In designing a set as, say, a living room,
it seems that the set designer has to decide whether to make the‘room’
with materials that are as they seem to be (the‘room’seems to be and in
fact is made of plaster, bricks, etc.) or which are not as they seem to be
(the room seems to be made of plaster, bricks, etc., but is in fact made of
cardboard, canvas, etc.). A typical set may well make use of at leastsome
scenery that is not what it appears to be; so, if the latter is a kind of
illusion, then it seems that illusion is at least a common feature of theatre.
I call this‘set-design illusion’, but it could be a feature of props and of
the actors’costumes, too. (A‘live’example might be the well-established
although now unfashionable practice of dressing up children to look like
adults, and then placing them at the back of the stage to make it look
further away.) The key point is that (unlike some other illusions that we’ll
discuss) these illusions, if they are such, could arise from a static view or
snapshot of the stage and actors: we are talking about the materials of the
set and costumes, perhaps the make-up, lighting and so on.
It is important not to exaggerate the use and effectiveness of this kind
of illusion. Often sets, costumes, lighting and sounds are aids to imagination
rather than attempts to fool an audience. A man sitting on a simple, wooden
chair and wearing a paper crown does not produce the illusion that we are
looking at a king, seated on a throne in full, splendid regalia; what we see
58 From the World to the Stage