Socrates told us that nothing is more important than living a decent life, having a ‘healthy soul’, but that a kind of knowledge is essential in order to do this. We need to know both what it is to live well and how to do it. Philosophy is the way to get this knowledge, so we need philosophy.
But what is philosophy, when it’s not Socrates asking a lot of questions? It is the exercise of reason. We apply our intellectual powers to a problem and try to think it through. It’s not like kicking a football or playing the drums: you can try to think these things through, but for the most part they are about hitting stuff, physically doing something.
Philosophy is an activity of the brain more than the body; even when it’s something that is done, it’s something that is done by thinking.
Plato, a student of Socrates, slowly moves into this realm of pure thinking. In Plato’s mature philosophy, there’s less focus on conversation, less focus on the down-to-earth ethical questions about whether this or that is a good thing or not, and more focus on the pure pursuit of abstract intellectual understanding.
Two Worlds
This shift in emphasis leads Plato to make an important discovery: there is a world that we see with our eyes and a world that we see with our minds.
When we look around, using our eyes, we can see a bunch of things. I might see a lovely painting of a horse, for example, hanging on the wall of an art gallery. This is a physical object – a painting of a horse – that represents another physical object: a horse.
In a sense, the actual horse is ‘truer’ and ‘more real’ than the painting of the horse. A painting is but a faint copy, whereas the horse is really real. When I look at a painting of a horse, I can see a representation or image of the horse, but I can’t reach out and touch the horse, only the painting; the horse isn’t really there.
The painting is inherently less reliable as a representation of reality than the horse itself: we can ask of the painting of the horse ‘is that an accurate representation?’, whereas the horse itself just is.
The distinction here is between what Plato calls ‘images’ and ‘visible things’. Things are more real than their images, but at least both of these we can see with our eyes.
But what about mathematical objects like triangles or numbers? Obviously we can see the representations of these things with our eyes when we draw a triangle or write down some numbers. But these are only representations of the numbers, not the numbers themselves; they are like the painting of the horse, not the horse itself.
How can we ‘see’ the numbers or shapes themselves? With our eyes, we obviously cannot, because they are not physical objects. Shapes and numbers are mathematical objects. We ‘see’ them with our minds. We learn our numbers and understand what a triangle is by learning a thing or two about mathematics and geometry. We use physical representations to do this, but those representations should not be mistaken for the reality itself. In reality, the numbers and shapes do not physically exist in this world but exist immaterially in the world of the intellect.
What we are left with is a division between the ‘visible world’ and the ‘intelligible world’. The visible world is the world that we can see with our eyes, but we needn’t limit ourselves to the metaphor of vision here and could just as easily talk in terms of ‘hearing’ or ‘touching’, or even ‘smelling’, so we can call this the ‘physical world’; the intelligible world is the world that we can see (or hear, feel, sniff) with our minds.
Dualism
This is the birth of the very long-standing philosophical theory of ‘dualism’. This theory says that there are essentially two kinds of stuff: physical stuff and mental stuff. Physical stuff is material, existing in time and space, mental stuff is not. Because mental stuff is immaterial, it doesn’t exist in time or space, and therefore exists eternally. It is this simple inference that provides the philosophical foundation for ideas about the immortality of the soul.
The Priority of the Intelligible World
There is a hierarchy of reality for Plato here. A picture of a horse is less real than the horse that it represents. The picture is just a representation of that actual object. Likewise, a drawing of a triangle is less real than the concept of a triangle. The drawing of a triangle is just a representation of that actual concept. What this means is that, as counter-intuitive as it may seem, the world we see in our minds is more real than the world we see with our eyes: the intelligible world is more real than the visible world.
But if the intelligible world is more real than the visible or physical world, and we want to understand reality itself, then we should try to understand the intelligible world rather than the physical world. And this gives priority to the world of pure reason, rather than down-to-earth physical reality. We should trust our intellect and not our eyes.
Ironically (because this all sounds very unscientific to modern ears), we are forced into agreement with Plato when we consider how we tackle the hardest problems in physics. At the boundaries of theoretical physics, there are no observations that can be made, nothing that can be seen with our eyes (or even our measuring apparatus). We trust instead to the pure reason of mathematics.
Where you draw the line between the ‘observable’ and the ‘non-observable’ is a controversial question in the philosophy of science, but it’s clear that there probably is a line to be drawn somewhere and theoretical physicists regularly cross over it. They postulate theoretical entities, unobservable but no less real for that. These ‘intelligible objects’ are things that we can see with our minds, with our understanding, and we trust that they are real, that the physical world does align with these intelligible realities. We take these intelligible realities to be reflective of reality itself. But we have long since abandoned the idea that we are directly looking at actual physical stuff.
The best physicists understand the world at that intelligible level, not just the physical or visible level. Plato’s philosophy is a direct analogy here: the best knowledge is knowledge of the intelligible world, not of the physical or visible world. The best philosophers, therefore, will understand the world at that other-worldly level.
But it needn’t be as complicated as theoretical physics. The basic idea is intuitive for day to day things: we use reason to correct our perceptions.
The classic example is two people stepping into water. The first person is hot from sitting in the sun, so when they step into the water the water feels cold to them. The second person is cold from sitting in an overly air-conditioned room, so when they step into the water the water feels warm to them. So is the water cold or warm?
The first person perceives this ‘material reality’ one way, the second perceives it a different way. They each have their ‘opinion’ about the temperature of the water, and one of them might have the ‘true opinion’, but neither has ‘knowledge’ because they are only reporting things as they seem to them.
What is the right answer here? To find the ‘truth’ about the temperature of the water, we step back from either person’s perception and rely on an objective measure: a thermometer gives us a reading in terms of a perfected idea (or theory) that we have about temperature. We represent this idea using numbers on a scale. This, we think, is more real than any one person’s perception because it captures the ‘intelligible reality’ of temperature.
The best understanding of temperature is found at that intelligible level. This is how we turn mere ‘opinion’ into ‘knowledge’. We measure heat according to our perfected idea of it, not muddied by our faulty perceptions. If someone feels the water to be warm, when it objectively isn’t, then we say ‘you only feel that way because you’re cold’. The person’s perception can be wrong, corrupted, biased, dishonest, or mistaken, but the thermometer never lies.
It needn’t be complicated, and it needn’t be scientific either. Put someone in front of a work of art when they are in a bad mood and they might think that what they’re looking at is junk and nonsense that has no value. Put the same person in front of the same work of art when they are in a better mood and they might see it differently. The art hasn’t changed, but the person’s perception of it has, having been altered by their mood. What is the truth of the ‘beauty’ in the work of art? Can we trust to this person’s fickle opinion? Instead, let us step back and consider what our perfect ‘idea’ of beauty is and whether that idea is represented in this artwork. The highest understanding will operate at that intelligible level, according to Plato.
Read more: Think Well, Live Well: A Free Introduction to Philosophy
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