Joanna asked:


I am Joanna and I am 8. My mum found this site for me because I really want to know how I can be sure that everything is actually real and that the things I can see and hear and touch and smell and taste are not just me imagining everything? And how do I know that my mum is real (even though she helped with the typing) and that I am even real? Thank you for helping me with this question because it is making it hard for me to get to sleep at night.

Answer by Nathan Sinclair

Hello Joanna,

Like you, lots of clever people have worried about this question. In ancient Greece there was a man who thought there was no reason to believe anything he saw or touched was real, and the story goes that his friends spent a lot of time pulling him back from walking off cliffs and in front of chariots and so on.

More recently, about 350 years ago, a French philosopher called Descartes (said: DAY-CAR) tried to work out why we should believe that what we see is real, and he thought he found the most basic truth on which everything else we know depends. This basic truth is the famous saying ‘I think therefore I am’. Even if everything you see and feel isn’t real, your sights and feelings are still real themselves, and from this basic truth Descartes thought he could give reasons to believe everything else. His argument was that since I exist something better and smarter than me must have made me, and that something must be God and God wouldn’t make me see and feel things that aren’t real. If you think this argument for God isn’t very good you are not alone. Lots of Descartes’ friends thought this argument was so bad that Descartes didn’t really mean it and secretly didn’t believe in God at all. But without a good reason to believe in God Descartes doesn’t have any reason to believe what we see and feel.

Nowadays many philosophers think the reason for believing that what you see is real is that it is the best explanation of your seeings and feelings (your experiences). If your mum existed and your eyes and ears worked that would explain why you heard your mum telling you it was time to go to bed at night, and saw her looking for you if you didn’t answer. It seems really unlikely that you would have a hallucination as complicated and as organised as what you see and feel.

I don’t think the appeal to ‘best explanation’ is much good at all, I don’t know how to judge explanations and I suspect its mainly just fitting in with what you already know. Instead lets look at two suggestions I find helpful

1) Your experiences are so complicated there has to be something behind them.

Lets try a simpler question for a moment: How do you know there is more to your computer than what you see on the screen? Well, when you close a window on your computer and then open it later the same stuff appears in it. That stuff wasn’t shown anywhere but the computer had to remember it, so wherever the computer stores that information isn’t being displayed, so the computer must have some hidden parts that aren’t shown on screen. Well maybe it just stores stuff, so there is nothing more in your computer than what is on screen at some time or other. But that can’t be right because sometimes the computer does complicated calculations. Calculations so complicated that is has to store intermediate results on the way to working out the full answer. (Something like the way you might write down part of a sum on the way to working out the final answer to a maths problem, but so complicated that there is no way the final answer can be worked without storing intermediate results along the way.)

In the same way, provided you believe that there are complex patterns in your experiences, provided you believe that when you open your eyes next you will see your hands and the room around you and so on, then you must believe in the external world (the external world is where the world writes down its intermediate answers while it works out what to show you next). To say it in a negative way, if you don’t believe in the external world then you can’t believe that the world works really hard to figure out what to show you next, the world isn’t doing really hard calculations (how fast does a ball fall, just where will rainbows appear and so on) and the complex patterns you think you see in the world really aren’t there and there is no reason to think that you will go on seeing things fall down when you let go of them, the sun rise in the east tomorrow, your mum say ‘Good Morning’ to you tomorrow and so on (your experiences are like random dots that happen to make a picture but really they are just random and the picture will get wiped out by the next lot of random dots) — No real world, no complex patterns! To say it in a positive way, if the patterns in what you see and feel are real then what you are seeing/feeling is so complicated that there must be a real world behind them where those patterns are worked out.

2) You don’t start from nothing.

The way you and Descartes set up the problem, it seems like we need something fundamental that can’t be doubted to show that the world is real (or the patterns we see are genuine patterns). Maybe if we started not believing anything there is no way we could ever learn anything. (Maybe if we were stuck at the bottom of a well with no climbing equipment we could never climb out and go buy some climbing equipment.) But that doesn’t matter because we don’t start believing nothing, we start with lots of beliefs and we change them in response to what we experience. We are not like builders building a new house on a vacant lot, we are like renovators who move into an existing house and then do it up to make it nicer. Given that you already believed in the external world what new reason is there to change your mind and reject it? This is not simply a matter of which belief got in first, but of recognising that you must start from where you are now. This doesn’t really answer your question but suggests that the question didn’t accurately reflect the real problem we face which is working out what we should believe next GIVEN what we see/feel AND what we already believe in now.

These are the things that let me sleep at night and not worry if my children are real or if they are going to be there when I get up in the morning, I hope they help you too.