Reality of the chair, its molecules, and the perception

Jane asked:

Which is most real, the chair you are sitting on, the molecules that make up the chair or the sensations and images you have of the chair as you are sitting on it?

Your help is very much appreciated.

Answer by Jürgen Lawrenz

This is a really good question, even though it’s been asked 1000 times before. The trouble is, philosophers have a tendency to over-elaborate the simplest of matters. So I’m going to give you a short, but accurate explanation.

(1) There is only one chair. It is that with which your backside makes contact when you sit on it.

(2) The molecules are not a chair, but a heap of molecules. Molecules make matter, they don’t make chairs. So if you choose to call that heap of matter a chair, that’s your business. Like calling a heap of stars the Andromeda galaxy. Well, that’s what we humans do. But that’s our problem – a problem that has to do with language use. In the dimension where molecules live, there are no chairs. So the answer to (2) is, a chair defined as a heap of molecules is a misuse of a technical term. Has nothing to do with being real or not real.

(3) The chair in your mind is an image. Perceptions pick up visual data like chairs from the world. But they can’t bring chairs into your head, so they manufacture an image. How can this be real? If you reply, there are people who say so, you reply: if there was no chair in my field of vision, I would not see a chair. Therefore the chair image cannot be the real chair. Of course you can always imagine a chair, but then you can’t sit on it. And that’s the difference.

Answer by Craig Skinner

I will assume that there is an external world of material objects and other people who, like me, have a mental life. In short I wont consider either solipsism or idealism (a la Berkeley)

The things you cite are all three equally real, but don’t all have the same kind of reality.

To be real is to actually exist. To be an existent entity.

I exclude nonexistent entities (possible ones like unicorns, impossible ones like round squares) and fictional entities (like Sherlock Holmes). We may talk of these as having possible existence or fictional existence, but they don’t have actual existence, and that is the hallmark of reality.

There are no degrees of reality (real, more real, most real). Rather there are kinds of reality or ways of being real.

One classification of ways of being real, is that there are universal entities (includes properties, such as redness; and relations, such as betweenness) and particular entities.

Particular entities can be abstract (eg numbers) or concrete.

Concrete particulars can be things (physical, or mental) or events (eg collisions).

So, the three things you cite (chair, molecules, sensations) are all equally real but in different ways:

• The chair has reality as a physical concrete particular (thing).

• The molecules are similar. They are (smaller) physical concrete particulars (things).

• The sensations and images are mental concrete particulars (things).

To expand a little on each:


It is a big physical object or thing, a physical concrete particular. It’s chairness lies not just in its being a collection of bits of wood: a pile of firewood or fallen branches is that. It was built AS a chair and is seen as this by those who have the concept. So, if floating in the sea, it would be seen by a dolphin as an entity but not seen AS a chair. An ant might crawl over it, and perceive it in an anty way, but not perceive it AS an entity. But none of this affects the chair’s reality, its actual existence, it affects only what we (and dolphins and ants) know and think about it.


Traditionally, unobservable entities postulated by science are not afforded full reality. They are theoretical rather than real, instrumentally useful in explaining what we find in the world. And so it was once upon a time with atoms and molecules. But now, in my view, they can be regarded as being as real as chairs. We can see molecules these days with ultra powerful microscopes (although strictly we don’t see THEM, we see enlarged images of them), and there must be few people nowadays who think DNA molecules are less real than chairs. Of course superstrings, dark matter and Higgs bosons have taken the place of atoms as unobservable postulated entities which may or may not be real.

Sensations and Images:

These are mental rather than physical entities. But the mental is just as real as the physical. It differs in being private, so that my sensations of the chair are mine only (and yours yours) whereas the chair or its molecules are publicly observable. Of course our sensations concur because we are aware of the same chair. So if we have normal vision and view the chair in good light we both see it as having the same colour. To be sure, mental entities depend for their existence on a physical substrate (or so I believe). Thus our images and sensations of the chair are the mental activity of our brains, probably patterns arising from coordinated nerve cell firings. But this doesn’t diminish the reality of the mental entities. Some mental entities are fleeting, such as the sensation in my elbow as I presently rest it on the arm of my desk chair, but others, such as my memory of my childhood by the seaside, have lasted longer than some of the chairs in my house, and these memories have been in (or can be recalled into) my mind for far longer than any of the atoms which currently comprise my brain have been part of my body.

As Richard Feynman, the famous physicist, put it when explaining the importance of a paper on the half-life of radio-phosphorus in rat brains: ‘We tend to overlook how astonishing it is that yesterday’s potatoes can, today, remember my boyhood in New York’.

Answer by Helier Robinson

First of all the word real has several meanings: (i) it is all that exists independently of being perceived (that is, it exists whether anyone perceives it or not); (ii) it is all that we perceive around us that is not illusory; (iii) it is what makes propositions true or false; (iv) it means genuine, as opposed to artificial.

Secondly, there is an important logical principle that is relevant here: qualitative difference entails quantitative difference. (Proof: whatever A and B may be, if there is a qualitative difference between them then there is some quality, Q, such that A is Q and B is not-Q (or vice versa); if A and B are one then one thing is at once Q and not-Q, which is impossible; hence A and B are two.)

The chair made of molecules is qualitatively different from the chair you are sitting on, which is made up of sensations and images, so they cannot be one and the same chair, they have to be two. (For example, molecules are not made up of sensations and images and the chair you are sitting on is so made up.)

In fact, the molecular chair is theoretical and the chair made up of sensations is empirical, and it is a curious fact that the theoretical and the empirical are disjoint: nothing theoretical is ever empirical and vice versa. (The empirical is known by the senses and the theoretical is known by the mind.) The theoretical is real if it exists, since no one ever perceives it, and the empirical is real if it is free of illusion; so these two meanings of ‘real’ are not equivalent, and it is impossible to say which of them is ‘most’ real.

However, there is a neat philosophical problem here. You use the word image in connection with sensations, implying that the empirical chair is an image of the theoretical chair; and, indeed, this is what we suppose from theory of perception. Does this mean that the empirical you, sitting on the empirical chair, is an image of a theoretical you, sitting on a theoretical chair? (Naturally, the empirical you is made up of sensations and the theoretical you would be made up of molecules; and the two have to be qualitatively different.) And, if there is this theoretical you, where is it, since two distinct things cannot exist in the same space? Think of this as an opportunity to discover how philosophically talented you are. (If you are really stuck on this problem, try going to

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