Monica asked:

What is the philosophy problem of appearance and reality and how is the problem relevant to people of the 21st century?

Answer by Helier Robinson

Appearance is what we perceive around us; it is sometimes known as the empirical, which means known through the senses. Reality is most commonly defined as all that exists regardless of whether it is perceived or not; in other words, it exists independently of anyone’s perception. According to common sense appearance IS reality: objects that we perceive around us continue to exist when no one is perceiving them; this is known as realism. But there are two difficulties with this. One is that everything that we perceive is illusory to some extent, and illusions are unreal. If you doubt this, try to point to something that you perceive which is wholly free from illusion, and explain how you know it to be so. Furthermore, there is only one reasonable explanation of illusions: namely, that they are misrepresentations of reality, in which case they are images of reality, not reality itself. The second difficulty is that everything we perceive around us is composed of sensations: colours, sounds, tactile sensations such as various degrees of hard and soft, hot and cold, rough and smooth, solid and liquid, and forces such as weights, inertia, and electromagnetic forces, as well as tastes and smells. These are what philosophers call secondary qualities and they are manufactured in the brain as a result of real data stimulating the sense organs. But if everything empirical is made out of secondary qualities it must be inside the perceiver’s head, private, and mental; while it is a fact that everything we perceive is outside our heads, public, and material. So that is the problem: are appearance and reality one and the same, or are they quite different things?

There is a solution, which is logically easy but psychologically difficult. If all appearances are images of reality rather than reality itself (because of being somewhat illusory and composed of sensations) then your own body, which is also an appearance, is an image of your real body. This means that beyond the apparent blue sky on a sunny day is the inside surface of your real skull.

The relevance of this for people of the 21st century (or for any other century) is that common sense is wrong about realism, just as it was wrong about a flat Earth, geocentrism, and evolution. If you are a genuine seeker after truth you must not be complacent about common sense. Common sense is wonderful for everyday living but not for philosophy or science.