Perception

Awareness of the world through the senses - and the question of whether it delivers the world or a version of it.

Theme: Knowledge, truth and reason
Tradition: Cross-tradition
Term: ἐπαντία-adjacent · aisthēsis
Term fixed: c. 330 BC

In plain terms

Perception feels like a window. You open your eyes and the world is there, with no sense of anything intervening.

Everything known about how it works says otherwise. The input is fragmentary, the eye moves several times a second, there is a hole in each retina you never notice, and a great deal of what appears stable and detailed is supplied rather than received. The seamlessness is an achievement, not an absence of processing.

Which leaves the philosophical question. If what you are aware of is constructed, is it the world you are aware of, or the construction? Direct realists say the first and have to explain illusion. Indirect theorists say the second and have to explain how anything gets through. Nobody has made either side comfortable.

As a philosopher would put it

Aristotle's account has the sense organ take on the form of the object without its matter, which makes perception a genuine relation to the thing. The modern problem is created by the primary-secondary distinction: if colour and sound are effects in us, then what is immediately present to the mind is not the object.

The argument from illusion drives the classical debate. If a stick in water looks bent, something bent is being perceived, and it is not the stick - hence sense-data. Direct realists reject the inference: looking bent is a relational fact about the stick in those conditions, not the presentation of a second object.

Contemporary positions divide over representation. Representationalists make perceptual experience a matter of content that can be accurate or not; relationalists insist that experience is constituted by acquaintance with the object itself. Nyāya's pratyakṣa is realist and includes a determinate stage in which the object is perceived as being of a kind; Buddhist epistemology restricts perception to a bare particular and treats everything conceptual as inference, which is a sharper division than any European account draws.

Where you meet it

In 1998 Daniel Simons and Daniel Levin ran an experiment on the Cornell campus. An experimenter with a map stopped a pedestrian to ask directions. Mid-conversation, two people carrying a door walked between them, and behind the door the experimenter swapped places with a different person - different height, different build, different clothes, different voice.

About half the pedestrians carried on giving directions without noticing that they were now talking to someone else.

The result is not about inattention in the ordinary sense: the subjects were looking directly at the person and were engaged in conversation with them. What it demonstrates is that the impression of a rich, continuously updated scene is not what the visual system maintains. It maintains enough to act on, and the sense of having had the whole scene available is generated after the fact - which is a fact about perception, and a problem for any account that treats it as a window.

What is actually disputed

Whether we perceive the world or a representation of it.

Direct realism has intuition on its side and the argument from illusion against it. Indirect theories handle illusion and hallucination cleanly and struggle to explain how the intervening item is not a veil - which was Berkeley's point, that once you admit an intermediary you have no route back to the object.

Disjunctivism attempts an escape by denying that veridical perception and hallucination share a common element; critics find the denial hard to accept given that they can be indistinguishable from the inside. Meanwhile the empirical work on prediction and construction cuts against naive versions of both. What is not disputed is that the phenomenology is misleading: perception presents itself as passive reception, and it is not.

Commonly confused with

observation in science Scientific observation is theory-laden and instrument-mediated by design. Perception is the ordinary capacity those practices are built on top of.
Qualia 1929 Qualia are the felt character of experience. Perception is the capacity that puts you in contact with objects, and one can be discussed without the other.

Defined against

Appearance and reality Perception is where the distinction bites hardest, since it is the faculty supposed to deliver the second and demonstrably delivers the first

Philosophers

Aristotle Perception as receiving form without matter
John Locke Primary and secondary qualities, and the intermediary that follows
George Berkeley The argument that the intermediary leaves no route back
Thomas Reid Direct realism defended against the way of ideas
Maurice Jean Jacques Merleau-Ponty Perception as bodily engagement rather than reception
Vasubandhu The Buddhist restriction of perception to the bare particular

Works

Metaphysics The classical account
An Essay Concerning Human Understanding Where the modern problem is created
Three Dialogues between Hylas and Philonous The argument that the intermediary is fatal
An Inquiry into the Human Mind Reid's realist reply
Phenomenology of Perception Perception as embodied
Pramanavarttika The Buddhist analysis of perception and its limits

Schools

Peripatetic school (Aristotelianism) The classical realist account
British Empiricism Where the veil of ideas appears
Scottish Common Sense School Where it is rejected
Phenomenology Where perception is described from within
Nyaya Realist, with a determinate stage
Yogacara Buddhism Where the object side is analysed away

Related concepts

Experience c. 330 BC · Qualia 1929 · Appearance and reality c. 475 BC · Pramāṇa c. 200 · Knowledge c. 369 BC

Aristotle's account of aisthēsis as the reception of form without matter is the classical treatment; the modern problem begins when the primary-secondary quality distinction puts part of what we see into the observer.