Seeing aspects

Seeing aspects is the experience of looking at something that does not change and yet suddenly seeing it differently. The classic case is the duck-rabbit: the same lines, now a duck, now a rabbit. Wittgenstein calls this "seeing as" and the "dawning" of an aspect, and he spent much of his last years asking what it is. Is it seeing? Is it interpreting? Or something in between?

The discussion fills section xi of what used to be called Part II of the Philosophical Investigations. Since the 2009 edition by Hacker and Schulte that text is called Philosophy of Psychology: A Fragment and its remarks are numbered, cited as PPF.

What the animation shows

In the animation above you see the duck-rabbit. Click it and the label flips from "duck" to "rabbit" and back. Watch the lines closely: not one of them moves. The bill on the left becomes a pair of long ears, the back of the duck's head becomes the rabbit's mouth, but nothing in the drawing itself changes. What changes is what you see.

That is the puzzle in a single picture. If seeing were just receiving an image on the retina, there would be nothing to explain: the image stays the same. Yet you would not say that you merely "interpret" the drawing differently, as if you saw lines and then added a hypothesis. You see a rabbit. Then, all at once, you see a duck.

Wittgenstein did not invent the figure. He took it from the American psychologist Joseph Jastrow, who published it in 1899; an earlier version had appeared as a cartoon in the German magazine Fliegende Blätter in 1892 (see John Kihlstrom's note on its history).

Noticing an aspect

Wittgenstein introduces the theme with a face rather than a drawing:

Ich betrachte ein Gesicht, auf einmal bemerke ich seine Ähnlichkeit mit einem andern. Ich sehe, daß es sich nicht geändert hat; und sehe es doch anders. Diese Erfahrung nenne ich „das Bemerken eines Aspekts“.

I look at a face and suddenly notice its likeness to another. I see that it has not changed; and yet I see it differently. I call this experience "noticing an aspect".

Philosophical Investigations II xi (PPF §113)

The key is the "and yet". Two descriptions are both true at once: the object is unchanged, and my perception has changed. Wittgenstein says the expression of a change of aspect is the expression of a new perception together with the expression of an unchanged one. That is why the phenomenon is so strange, and so revealing.

Seeing as, seeing and interpreting

Wittgenstein distinguishes the "continuous seeing" of an aspect from its "dawning" (in German, Aufleuchten, literally lighting up). If someone has only ever known the figure as a rabbit, it would be odd for them to say "I now see it as a rabbit". They simply see a rabbit. The phrase "seeing as" only has a point where a switch is possible, where another aspect has dawned or could dawn.

He also resists two easy answers. It is not simply interpretation, because interpreting is something you do, a hypothesis that can be checked and turn out false, whereas the dawning of an aspect happens to you. But it is not simply seeing either, because aspects, unlike colours or shapes, are partly subject to the will: you can try to see the duck and succeed. The concept of seeing, Wittgenstein concludes, is more tangled than it looks; seeing as sits on the border between seeing and thinking.

Aspect-blindness

Wittgenstein then imagines people who are "aspect-blind" (PPF §257): they would see the drawing perfectly well and could copy it line for line, but would never experience the switch. Would they be missing something? He links this to a related question: what would someone lack who could use words correctly but never "experience the meaning" of a word, for example hearing a word as it was meant in a pun? These questions show that understanding is not just a matter of having the right information. It also involves a way of taking things in.

Why it matters beyond puzzle pictures

Seeing aspects is not a curiosity of perception psychology. It runs through Wittgenstein's whole later method. Much of his philosophy consists in getting us to see a familiar case in a new way: placing examples side by side until connections show up, as in family resemblance. He wanted to change how we look, not to add facts.

The idea also travelled. Historians and philosophers of science, from N.R. Hanson to Thomas Kuhn in The Structure of Scientific Revolutions (1962), used the duck-rabbit to describe how a scientific revolution can make the same data look entirely different. In aesthetics, seeing a melody as a variation of another, or a painted patch as a face, is close to what we mean by understanding art (see the Stanford Encyclopedia entry on Wittgenstein's aesthetics). Scholars disagree on how far the aspect remarks form a unified theory; many think Wittgenstein deliberately left them as an exploration, like the notes in his Remarks on the Philosophy of Psychology, written 1946-1949. The main SEP entry on Wittgenstein places them in his late work.

A small everyday version

You have probably had the experience of seeing a colleague in a new light after hearing them speak about something they love. Nothing about them changed in that hour, and yet you see them differently. Or a sentence you have read ten times suddenly makes sense. Wittgenstein would not call that a mystical event, nor a mere opinion. It is an aspect dawning, and noticing it is a skill you can practise: see changing the aspect for some concrete exercises.