‘The sun is actually white, it just appears yellow to us through the Earth’s atmosphere.’

This is a line that appeared on Facebook a while ago, courtesy of my friend Else Cederborg, who posts all sorts of curious and interesting things.

It is a common form of argument that most will readily understand and generally accept without thinking too hard about it. Yet the sun is not actually white, nor does it just appear yellow, facts you can easily check for yourself.

Depending on the time of day and the atmospheric conditions, the sun is variously deep blood red, orange, dusky pink and (behind a veil of mist or thin cloud) a sort of milky white; much of the time it has an incandescent brilliance which can hardly be called a colour since we cannot bear to look at it directly. Though it may appear yellow, the usual place to encounter a yellow sun is in a representation of it: a child’s drawing, for instance (against a blue sky above the square white house, surrounded by green grass, with its four four-paned windows and red triangular roof with single chimney belching smoke) or else in the icons used in weather forecasting.

How we come to accept an argument that runs counter to all experience, and perversely insists on a condition for actuality (being seen outside the Earth’s atmosphere) which few of us will ever experience, is a case worth examining.

At the heart of it is that curious human thing, a convention (I say ‘human’ though it might be that other creatures have conventions, but that is for another time). A convention, effectively, is an agreement to treat things as other than they are – it is a form of pretence. This definition might seem surprising, since what is usually emphasised in conventions is their arbitrary character – the typical example being which side of the road we drive on, which varies from country to country.

However, what makes the rule of the road a convention is that we endow it with force, a force that it does not actually have: we say that you must drive on the left (or the right); that you have to – even though any one of us can show this not to be the case. Of course, if you engage in such a demonstration, you might find yourself liable to a range of legal sanctions, or worse still, involved in an accident. The fact that the rule has to be backed by force proves that it has no intrinsic force; on the other hand, the risk of accident shows that the pretence is no mere whim, but sound common sense: conventions are there because they are useful.

A great deal of human behaviour is conventional if you look at it closely: things are deemed to be the case which are not, actually (international borders is a good example – again, these are arbitrary, but it is the power with which they are endowed that makes them conventions). In this regard, it is worth recalling a remark that Wittgenstein makes somewhere (Philosophical Investigations, I think) to the effect that ‘explanation has to come to an end somewhere’. In other words, despite what we tell children, ‘just because’ is an answer. Conventions are so because we say they are so.

So what colour is the sun?

That takes us to the boldest and most fundamental of conventions, the one that underpins our standard way of thinking about the world, for which we have Plato to thank. Plato insists at the outset on discrediting the senses, saying that they deceive us, giving us Appearance only, not Reality.

This is a move of breathtaking boldness, since effectively it dismisses all experience as ‘unreal’ – as a starting position for philosophy, it ought to be quite hopeless, since if we cannot draw on experience, where are we to begin? If reality is not what we actually experience, then what can it be?

However, there is a different angle we can consider this from, which makes it easier to understand how it has come to be almost universally adopted. What Plato is proposing (though he does not see this himself) is that we should view the world in general terms: that we should not allow ourselves to be distracted by the individual and particular, but should see things as multiple instances of a single Idea or Form; or, as Aristotle develops it, as members of a class which can be put under a single general heading: trees, flowers, cats, horses, at one level, plants and quadrupeds at another, and so on.

Implied in this is the elimination of the subject: the world is not as it appears to me or to you or to any particular individual (since particular individuals exist only at the specific level) the world is to be considered as objective, as it is ‘in itself’, i.e. as a general arrangement that exists independently of any observation.

This is a very useful way of looking at things even though it involves a contradiction. Its utility is demonstrated by the extraordinary progress we have made in the 2.500 years or so since we invented it. It is the basis of science and the foundation of our systems of law and education.

Effectively, it starts by accepting the necessary plurality of subjective experience: we see things differently at different times – the sun is sometimes red, sometimes pink, sometimes incandescent; different people have different experiences: one man’s meat is another man’s poison. In the event of dispute, who is to have priority? That problem looks insoluble (though the extent to which it is an actual problem might be questioned).

So, we must set subjective experience and all that goes with it to one side, and rule it out as the basis of argument. Instead, we must suppose that the world has a form that exists independently of us and is not influenced by our subjective observation: we posit a state of ‘how things actually are in themselves’ which is necessarily the same and unchanging, and so is the same for everyone regardless of how it might appear.

This is how we arrive at the position stated at the outset, that the sun is ‘actually’ white, and that its ‘actual state’ should be taken as ‘how it appears from space,’ even though we live on earth and seldom leave it.

There is a confusion here, which has surfaced from time to time in the history of philosophy since Plato’s day. The strict Platonist would dismiss the whole question of the sun’s true colour in terms akin to Dr Johnson’s, on being asked which of two inferior poets (Derrick or Smart) was the greater: ‘Sir, there is no settling the point of precedency between a louse and a flea.’ Colour belongs to the world of Appearance, not the world of Forms or Ideas.

However, as the insertion of the argument about the earth’s atmosphere shows, we feel the need of a reason to dismiss the evidence of our own eyes (and this is where that little sleight-of-mind about ‘just appearing yellow’ comes in – so that we are not tempted to look too closely at the sun as it actually appears, we are fobbed off with a conventional representation of it that we have been accepting since childhood). The argument is that the atmosphere acts as a filter, much as if we looked at a white rose through coloured glass and variously made it appear green or red or blue: so just as we agree the rose is ‘actually’ white, so too the sun’s ‘actual’ colour must be as it appears unfiltered.

This, however, is specious. Leaving aside the fact that the rose is certainly not white (as you will soon discover if you try to paint a picture of it) at least our choice of default colour can be justified by adding ‘under normal conditions of light’ which most people will accept; but ‘as it appears outside the earth’s atmosphere’ can hardly be called ‘normal conditions of light.’

What has happened here is that the subjective ‘filter’ which Plato wished to circumvent by eliminating the subject – ‘let us ignore the fact that someone is looking, and consider only what he sees’ – has reappeared as an actual filter, so that the whole appearance/reality division has been inserted into the objective world by an odd sort of reverse metaphor. The need to give priority to one of the many possible states of the sun is still felt, and it is solved by arbitrarily selecting ‘the sun as it appears from space’ as its actual state, because that seems logical (though in fact it is not).

The subjectivity of colour in particular, and the subject-dependence of all perception in general, is like a submerged reef that appears at various periods in the sea of philosophy. Locke is troubled by colour, which he wants to class as a ‘secondary quality’ since it evidently does not inhere in the object, as he supposes the primary qualities – solidity, extension, motion, number and figure – to do. Colour is ranked with taste, smell and sound as secondary, which is just a restatement of Plato’s rejection of the senses in other terms.

Berkeley, however, sees that this is a specious distinction and gets to the heart of the matter with his axiom esse est percipi – ‘to be is to be perceived’. Everything we know requires some mind to perceive it: a point of view is implicit in every account we give. There can be no objective reality independent of a subject (as the terms themselves imply, since each is defined in terms of the other).

The response to this is illuminating. Berkeley’s dictum is rightly seen as fatal to the notion of an objectively real world, but instead of accepting this and downgrading Plato’s vision to a conventional and partial account employed for practical purposes, every effort is made to preserve it as the sole account of how things are, the one true reality.

Berkeley’s own position is to suppose that only ideas in minds exist, but that everything exists as an idea in the mind of God, so there is a reality independent of our minds, though not of God’s (a neat marriage of philosophy and orthodox christianity – Berkeley did become a bishop in later life. The Californian university town is named after him).

Kant’s solution is to assert that there is an independent reality – the ding-an-sich, or ‘thing-in-itself’ but logically it must be inaccessible to us: we know it is there (presumably as an article of faith) but we cannot know what it is like.

Schopenhauer’s solution is the most ingenious, and to my mind the most satisfying. He agrees that we cannot know the ding-an-sich as a general rule, but there is one notable exception: ourselves. We are objects in the world and so are known like everything else, via the senses – this is Plato’s world of Appearance, which for Schopenhauer is the World as Representation (since it is re-presented to our minds via our senses). But because we are conscious and capable of reflecting, we are also aware of ourselves as subjects – not via the senses (that would make us objects) but directly, by being us. (To put it in terms of pronouns: you know me and I know you, but I am I; I am ‘me’ to you (and in the mirror) but I am ‘I’ to myself)

And what we are aware of, Schopenhauer says, is our Will; or rather, that our inner nature, as it were, is will: the will to exist, the urge to be, and that this is the inner nature of all things – the elusive ding-an-sich: they are all objective manifestations of a single all-pervasive Will (which happens in us uniquely to have come to consciousness).

This idea is not original to Schopenhauer but is borrowed from Eastern, specifically Hindu and Buddhist philosophy, which belongs to a separate (and possibly earlier) tradition than Platonic thought does (it is interesting to note that a very similar way of looking at things has been likewise borrowed by evolutionary biologists, such as Richard Dawkins, with the notion of ‘the selfish gene’ taking the place of Schopenhauer’s ‘Will’ as the blind and indifferent driving force behind all life).

I find Schopenhauer’s account satisfactory (though not wholly so) because it is a genuine attempt to give an account of the World as we experience it, one that reconciles all its elements (chiefly us as subjects with our objective perceptions) rather than the conventional account of Plato (and all who have followed him) which proceeds by simply discounting the subject altogether, effectively dismissing personal experience and reducing us to passive observers. Although the utility of this convention cannot be denied (in certain directions, at any rate) its inherent limitations make it inadequate to consider many of the matters that trouble us most deeply, such as those that find expression in religion and art; and if, like those who wish to tell us that the sun is ‘actually’ white, we mistake the conventional account for an actual description of reality*, we end up by dismissing the things that trouble us most deeply as ‘merely subjective’ and ‘not real’ – which is deleterious, since they continue to trouble us deeply, but that trouble has now been reclassified as an imaginary ailment.

*perhaps I should say ‘the world’ or ‘what there is’. There is a difficulty with ‘reality’ and ‘real’ since they are prejudiced in favour of the convention of an objective world: this becomes clearer when you consider that they could be translated as ‘thingness’ and ‘thing-like’. The paradigm for ‘reality’ then becomes the stone that Dr Johnson kicked with such force that he rebounded from it, i.e. any object in the world, so that the subject and the subjective aspect of experience is already excluded.