QuestionsIs the world real?Representation only: we perceive without any external object
Is the world real?It is all in the mind

Representation only: we perceive without any external object

Vijñaptimātra ("representation only"); the Twenty Verses; Buddhist idealism; Yogacara

Vasubandhu c. 350 · c. 430Everything we perceive is only representation: we see things without any external object, as in a dream.
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What it claims

What we perceive is only representation (vijñaptimātra): there is no external object behind our perceptions.

Why

We sometimes perceive without any outer object, as in dreams, and the idea of an object made of atoms contradicts itself.

The same idea through history
Vasubandhu400Vasubandhu belongs to the Yogacara school ("application of yoga"), also called Vijñanavada ("the way of consciousness"). The Twenty Verses are his shortest and most discussed text on the subject: he defends the thesis there against the objections of the realists. The dating is uncertain (4th or 5th century).
George Berkeley1710A comparison, not a descent: thirteen centuries later in Europe, Berkeley also holds that sensible things exist only as perceived, with no matter behind. The two do not rely on the same reasons (atoms and dreams for Vasubandhu, the likeness of ideas for Berkeley) nor reach the same conclusion (an eternal mind for Berkeley).
In short

"Representation only: we perceive without any external object" is an argument by Vasubandhu (Vasubandhu, Viṃśatikā (Twenty Verses on Representation Only), 4th-5th century, 400) on the question "Is the world real?" (answer: it is all in the mind). Its claim: What we perceive is only representation (vijñaptimātra): there is no external object behind our perceptions. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P6, P7). AskPhilosophy presents 3 objections, 2 of them with a documented reply, and the original text behind each premise, checked word for word.

Vasubandhu, Viṃśatikā (Twenty Verses on Representation Only), 4th-5th century
Valid with an implicit premise

You dream that you are walking in a forest. You see the trees in a precise place, at a precise moment, you hear birds, you fear a wolf. Yet there is no forest and no wolf, only your mind. Vasubandhu, an Indian monk and thinker of the 4th or 5th century, draws a radical thesis from this: everything we perceive is only "representation" (vijñapti), even when awake. He is told that our perceptions are ordered (in a place, at a time), shared (several people see the same thing) and efficacious (objects act). He answers that the dream and above all hell prove the opposite: all the damned see the same guardians, who do not exist. He adds that the atom, the brick of the realists' matter, is contradictory. Careful: scholars discuss what exactly Vasubandhu asserts (see the debate below). And his aim is religious: to understand that our objects are projections, in order to be freed from them.

P1A perception can take place without any corresponding external object: people with an eye disease "see" hairs or moons that are not there, and we dream of things that do not exist.
P2Dream perceptions appear only in certain places and at certain times, like waking perceptions. That a perception is situated in a place and a time therefore does not prove that an external object causes it.
P3Several beings can perceive the same thing without any external object: all the beings in hell see the same guardians, the same river of pus, and undergo the same torments. But these guardians cannot be real beings who would suffer from the fire of hell like the damned: they are therefore shared appearances.
P4Perceptions without an external object can have real effects: in an erotic dream, the body reacts as when awake. The power to act is therefore not a proof of an external object either.
P5The only coherent external object that is proposed, an assembly of indivisible atoms, is contradictory: an atom touching several other atoms would have sides, hence parts; without parts, it could neither join with others nor cast a shadow on another. An object of perception is neither a whole without parts, nor separate atoms, nor an assembly of atoms.
P6 · implicit premiseIf none of the signs invoked to prove an external object (place and time, sharing, efficacy) is conclusive, and if the only coherent version of the external object is contradictory, then there is no external object.
P7 · implicit premiseIf there is no external object, then what appears to us is only representation.
Therefore what we perceive is only representation (vijñaptimātra): there is no external object behind our perceptions.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P6 and P7, one can accept the dreams, the damned and the incoherent atom, and still believe that external objects exist, made up otherwise than by indivisible atoms. Nothing in P1 to P5 forbids that.
The argument is valid. P1 to P5 establish five points: a perception without an object is possible, the three signs of the external object are also found without it, and the atom is incoherent. P6 draws from this that there is no external object, and P7 that everything is only representation. P6 is the strong premise: a realist can accept P1 to P5 and refuse P6, saying that the external object remains the best explanation.
Analogy. Several players are connected to the same online game. They see the same city, the same monsters, and fight together. Yet neither the city nor the monsters exist outside the computer. Vasubandhu says that shared perceptions of the world work like this, but without an external computer.

Objections

3

Each objection is a conversation: click to see who replies and where the debate stands.

T
The Abhidharma realists 400 · attacks premise 5

Buddhist realists (the Vaibhashika school) hold that the world is made of real elements. Vasubandhu's text gives his opponent the following objection: why not say that it is aggregations of atoms, not single atoms, that can be lit or hidden? An aggregation is a whole, not a mere heap of atoms.

Vasubandhu replies
Vasubandhu 400 · Reply in the text (verse 14, after Cronk)
Vasubandhu replies that this defence holds only if one admits that the aggregation is something different from the atoms that make it up. The opponent refuses to admit this, because an aggregation that was something other than its atoms would no longer be a mere collection of atoms.
The debate goes on (our summary) The debate goes on (our summary). Saṅghabhadra, a Vaibhashika realist thinker of the 5th century, composed two treatises to refute Vasubandhu's Commentary, and challenged him to a public debate, which Vasubandhu declined (according to the Stanford Encyclopedia, "Vasubandhu", § 1.1). We have not read these treatises and cannot summarise their arguments.
Where the debate stands (our summary)Disputed point between the Indian schools. The underlying disagreement: is a whole made of parts anything more than its parts? If so, the atom is no longer the last unit; if not, an aggregation can do nothing that its parts cannot do.
A realist opponent (objection raised by Vasubandhu himself) 400 · attacks premise 2

There is a significant difference between waking states and dream states. Everybody recognizes that objects experienced in dreams aren't real but mentally constructed. This is not recognized for objects experienced in waking states.

Vasubandhu replies
Vasubandhu 400 · Reply in the text (verse 17, after Cronk)
Vasubandhu replies that someone who is asleep does not recognize the unreality of the objects of his dream. It is only on waking that one sees through the dream. In the same way, it is only through spiritual awakening (what Buddhism calls the Buddha state) that one would see that waking objects are unreal too.
The debate goes on (our summary) The debate goes on (our summary). Vasubandhu holds that there is no inner sign proving that one is awake; Descartes thinks he finds one in coherence and memory, but he then grounds it on the goodness of a God. For Vasubandhu, the criterion is spiritual awakening, which one recognises only by reaching it.
René Descartes 1641
Much later, in Europe, and without having read Vasubandhu, Descartes writes that memory connects the events of waking life with each other and with our whole life, while it never connects our dreams. If a man appeared and vanished suddenly while I am awake, I would take him for a ghost. This is a sign that surely distinguishes the two states.
see the argument
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Kumārila Bhaṭṭa (Mimamsa school) 640 · attacks the conclusion

Kumārila, a philosopher of the Mimamsa school (c. 600-660), devotes a chapter of his Ślokavārttika, the Nirālambanavāda, to refuting the thesis of knowledge without an external object. According to the summaries we have, he holds that someone who denies the external object from the analogy of dreams can account neither for goal-directed action nor for perceptual error. He also holds that the thesis refutes itself: its proof is either internal to the mind (hence not objective) or external (and then contradicts the thesis).

no reply
No reply possible: objection raised in 640, after the author's death (430).
The debate goes on (our summary) The debate goes on (our summary). Later Buddhist thinkers answered Kumārila, for example Prajñākaragupta (c. 750-810) and Śāntarakṣita, who discusses his theses in his Tattvasaṃgraha (according to conference abstracts). We have read none of these texts.
Where the debate stands (our summary)Open point. Scholars also discuss what Vasubandhu asserts: an idealism in which the mind creates everything, or only the absence of any object external to consciousness (readings of Anacker and Lusthaus). Depending on the reading, Kumārila's objection hits more or less.