If we can’t rule out sceptical hypotheses, can we know anything about the world?

So we may be deceived by an evil genius^[1], or we may be a brain-in-a-vat. That makes answering this question quite difficult. However, if we take the question apart, that might make it possible to arrive to a conclusion.

Let us ask first if there’s anything we can know (whether it’s about the world or about something else.) Once we have an answer to that, we should ask if the nature of things we can know are about the world. In essence, we’re asking:

1. Can we know anything?
2. Does what we can know give us knowledge about the world itself?

Let’s start by answering the first question: Can we know anything? The answer, following Descartes, is yes: we can be certain that we exist.

What else, if anything, can we know? •

We have the impression of an external world existing, but that’s exactly that: an impression. There are many possible scenarios, some examples of which are:

1. this impression depicts an actual world, described as-is by our senses (eyes, ears, smell etc. — if any of those exist)
2. this impression is based on an actual world, but distorted by our brain to an unknown extent
3. this impression is entirely artificial, fed to our brain by external means (e.g. a computer, Matrix-like), stimulating our brain to create the picture we have
4. we are entirely artificial, but have some kind of a consciousness (see the German film ‘Welt am Draht’, or, ‘World on a Wire’ )^[2], and we are fed some kind of a picture similarly to (3).

There can be potentially many more scenarios that we can’t even start to imagine (just think of the question: ‘Can the brain ever understand itself?’)

Limiting ourselves to these four, imagine what diverse worlds could be behind each of them. If we can prove or refute whether they necessarily imitate a real world, we may be able to answer the question.

Case 1 — our senses depict the real world

In this case, our impressions of the world are correct — what we see is what there is.

Case 2 — our impressions of the world are distorted

In this case, we sense the real world, but the information is distorted to an unknown extent. There are things and/or beings we cannot see, and what we see is quite different from the actual thing in shape and colour. What we hear may be distorted too.

Think of the Babel fish in The Hitchhiker’s Guide to the Galaxy. It’s a tiny fish that goes into the ear and translates everything to the wearer’s language. What if we already have such devices? Maybe everyone else around us speaks some alien language. Can we say that in such a world, we can get any knowledge about the world itself? Maybe some, but that depends on just how distorted the world is.

Let’s pause here and think about whether we can rule out a significant distortion. We know that our memory is fallible. There have been many studies about this, for example the one where people were convinced that the room they were sitting in had different colour walls than they actually did (assuming the whole experiment happened in a real world with real walls, of course).

Or take the sheep behind the furry dog problem. Or hallucinations. So, we can’t really say we can always trust our senses. If we can’t always trust them, can we ever trust them? We can’t know when we they are failing us, so they may be constantly giving us inaccurate information. If this is possible, we can’t rule out a constant, significant distortion — therefore we can’t know much about this kind of world.

Cases 3 and 4

These cases are very similar in that our brain-in-a-vat or other form of consciousness is fed information about a world from an external source. This artificial world that we are fed must be based on something, and it is likely that this something will resemble a real world.

Why?

If we were to create an imaginary world, it would take immense effort to make it such that it doesn’t resemble our own world at all. We could, for instance, shape the creatures living in it like stones on a beach and speak in rumbles, but that world would still carry some resemblance to ours (there are similarly shaped objects in our world, and similar sounds). There are infinite aspects to every world (the laws of physics, the nature of time, what are things composed of, how do objects and creatures interact etc.) — for any civilisation to create a world that resembles their own, or something that has existed, is much more efficient than making up a whole new world.

This doesn’t mean we can point out anything we can know yet. Think about The Matrix. The ‘actual’ world there looks very different to our own, but the laws of physics are similar. However, they could be different, too! Just as meteorological conditions and the creatures living in that world are different, any other aspect could be — there is no way for us to deduct any property of the ‘real’ world from the perspective of someone living in the Matrix.

So — can we know anything? •

Based on these four scenarios, we can’t be sure.

There may be one aspect that is similar in all of these worlds though: time seems to be linear. But is it really? Even that, we don’t seem to know for certain.^[3]

A submission to Introduction to Philosophy on Coursera, 12 December 2020.