We are more inclined to say we see a different aspect, not that we interpret the picture differently, because seeing is a state, and interpreting is a thought. Interpretation implies a kind of hypothesis, and no such hypothesis exists when we see a duck-rabbit as a duck.


Wittgenstein does not direct us to any particular conclusion here, but rather asks us to consider a matter more closely. In discussing the many different ways we can talk about "seeing," he is trying to complicate certain notions that are most apparent in sense data theory.

The basic idea of sense-data theory is that what I see are not objects themselves, but intermediary "sense data." There are a number of arguments for this position. In different lights, a room may look different, but the room itself does not change; therefore, it must be my sense data that change. When I see a stick half-submerged in water, it appears bent, but it is not bent; the bent stick occurs only in the realm of sense data. When I hallucinate, I see all sorts of things that don't really exist; they are only sense data.

A theory of sense data raises immediate skeptical questions. If what I see are not the things themselves, but only sense data, then how can I know there is any world external to my sense data? I could be a brain in a vat, hooked up to wires that give me the appropriate sensations at certain times. On a less far-fetched level, scientific investigation needs a foundation that acknowledges sense data, and not things themselves, as its object of study. Bertrand Russell and Rudolph Carnap have both made notable attempts to set forth such a foundation.

Wittgenstein's argues that seeing is a far more complicated activity than the sense-data theorists assume. We misuse words like "see" and "interpret" when we assert that all we see are sense data, and that we interpret these sense data as certain kinds of objects in the world. I do not first see a silver sense data of a certain shape and then interpret it "as" a fork. The example of the duck-rabbit is, among other things, meant to bring out when we can correctly speak of seeing something "as" something.

There are two obvious flaws with this notion that we see sense data and then interpret them as certain objects. First, we do not see sense data, and second, no act of interpretation takes place. The first point can again be demonstrated through the example of the duck-rabbit. Someone who is unaware of the duck aspect is just as justified in saying, "I see a rabbit," as someone who says, "I see a fork." We could say the same for someone unaware of the rabbit aspect saying, "I see a duck." Both these people have the same "sense data," but they are seeing two different things.

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