QuestionsIs the world real?The world is my representation
Is the world real?It is all in the mind

The world is my representation

"The world is my representation"; no object without a subject; Schopenhauer's idealism

Arthur Schopenhauer 1788 · 1860Life swings between suffering and boredom.
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What it claims

The world as we know it is my representation: without a subject to perceive it there is no world-as-object, and it is wrong to say that matter exists first and then produces knowledge.

Why

Everything I know, I know as an object for a subject: the whole world exists only for a being that perceives it.

The same idea through history
George Berkeley1710Schopenhauer says Berkeley was the first to state this truth clearly (§ 1). But Berkeley adds a God who perceives everything; Schopenhauer stays with the general form: an object always presupposes a subject.
In short

"The world is my representation" is an argument by Arthur Schopenhauer (The World as Will and Representation, book I, 1819, §§ 1 and 5-7) on the question "Is the world real?" (answer: it is all in the mind). Its claim: The world as we know it is my representation: without a subject to perceive it there is no world-as-object, and it is wrong to say that matter exists first and then produces knowledge. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P3). AskPhilosophy presents 3 objections, 2 of them with a documented reply, and the original text behind each premise, checked word for word.

The World as Will and Representation, book I, 1819, §§ 1 and 5-7
Valid with an implicit premise

Look at the sun. What do you really know of it? Only what your eye sees of it. Look at the earth: only what your hand feels of it. For Schopenhauer this is the most certain truth there is: everything we know is an object for a knowing subject. The world as we know it is therefore only "representation", and there is no object without someone to whom it appears. Careful: he does not say the world is a dream, or that matter does not exist for science. He says matter exists as an object, so for a subject. And he adds that this is only half the truth: what the world is in itself is not matter but what he calls will, a blind force we know from the inside through our own body. This page deals only with the first half, "the world is my representation".

P1All that exists for knowledge, and so the whole world, is object only in relation to a subject: it is the perception of a perceiver. This holds of the past and the future as of the present, of the farthest as of the nearest, since it holds of time and space themselves.
P2Subject and object always go together: the object always presupposes the subject. Neither is the cause of the other. The outer world is therefore neither the cause of our representations nor their effect.
P3 · implicit premiseMatter, the body and everything science studies belong to the known world: they are objects, not realities standing outside all possible knowledge.
Therefore the world as we know it is my representation: without a subject to perceive it there is no world-as-object, and it is wrong to say that matter exists first and then produces knowledge.

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 P3, the computer finds a case where everything known is an object for a subject, but matter is something other than a known thing: it would be hidden behind the representations, and the conclusion would not concern it.
The argument is valid with the hidden premise P3. If everything known is an object for a subject (P1), if the object always presupposes the subject (P2), and if matter and the body belong to the known world (P3), then the known world is representation. The objections target P1 (being known is not being in the mind) and the conclusion (common sense says the world exists without us).
Analogy. A film exists as an image only on a screen and for viewers. Without screen or viewer, there is film stock but no image. Schopenhauer says: the world we see is like the image, it always presupposes someone who sees it.

Objections

3

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

Bertrand Russell (act and object of knowledge) 1912 · attacks premise 1

Russell criticises this kind of reasoning in Berkeley. We must distinguish the act of perceiving (which is in the mind) from the thing perceived (which has no reason to be). From "I know the colour only if I perceive it" we cannot conclude "the colour is in my mind". Saying that known things are "in the mind" mixes the two senses.

no reply
No reply possible: objection raised in 1912, after the author's death (1860).
The debate goes on (our summary) Our summary: Russell writes almost a century after Schopenhauer and targets Berkeley, not him. Schopenhauer could reply that he does not say the world is "in" the mind like an idea, but that it is always "for" a subject (an object in relation to a subject). It remains to ask whether that relation is itself too strong a claim.
Where the debate stands (our summary)Our summary: an open point. Idealists say that "being known" only makes sense for a subject. Realists say the known thing existed before and exists without being known.
Bertrand Russell (the simpler hypothesis) 1912 · attacks the conclusion

If the cat existed only when I see it, it would spring from nowhere at each appearance and its hunger would be inexplicable. It is far simpler to suppose it exists when I am not looking. Every principle of simplicity urges us to believe there are objects independent of our perceptions.

a defender replies
see the argument
Schopenhauer (empirical reality, transcendental ideality) defender of the argument · 1819 · Schopenhauer's reply
Schopenhauer does not deny the cat or matter: denying their solidity would be lunacy. He only corrects the idea that they exist outside every possible subject. The cat, its movements and its hunger are real in experience, and this reality is that of an object for a subject. He cites the formula of the Indian Vedanta tradition: "existence and perceptibility are convertible terms".
Where the debate stands (our summary)Our summary: both sides agree the cat exists in experience. The disagreement is about what "existing when nobody looks" means: existence with no possible subject at all, or only possible perception.
The objection from science (which Schopenhauer raises himself) 1819 · attacks the conclusion

The natural sciences show that inorganic matter existed before plants, plants before animals, animals before man: the world had to pass through a long series of changes before the first eye could open. How could the world depend on a subject, if it existed before any subject?

a defender replies
Schopenhauer defender of the argument · 1819 · Schopenhauer's reply
Schopenhauer accepts this result of science, but replies that this long course of ages is itself only thinkable in a consciousness: time is the form of its knowing, and apart from it time is nothing. The existence of the whole world thus still depends on the first eye that opened, even an insect's.
Where the debate stands (our summary)Our summary: Schopenhauer himself calls this conflict an "antinomy" in our faculty of knowledge: the world depends on the first knowing being, and that being depends on a long chain of causes. For realists, this shows the thesis goes too far; for him, it proves that time belongs only to representation, and that the world in itself lies elsewhere.