Part 1

The Difference Between Our Sensations and the Things That Produce Them

by Rene Descartes Icon

Rene Descartes 1639

FIRST MEDITATION: What can be called into doubt

Some years ago, I was struck by:

  • how many false things I had believed
  • how doubtful was the structure of beliefs that I had based on them.

I realized that if I wanted to establish anything permanent in the sciences, I needed – just once in my life – to:

  • demolish everything completely
  • start again from the foundations.

It looked like an enormous task. I decided to wait until I was old enough to be sure that there was nothing to be gained from putting it off any longer.

I have now delayed it for so long that I must get to work. So today, I will devote sincerely and without holding back, to demolishing my opinions.

I can do this without showing that all my beliefs are false.

My reason tells me that I should withhold assent from propositions that are:

  • obviously false
  • not completely certain.

So all I need to reject all my opinions is to find at least some reason for doubt in each of them.

Go for the Jugular

I can do this without going through them one by one. Once the foundations of a building have been undermined, the rest collapses by itself. So I will go straight for the basic principles of all my former beliefs.

Whatever I have accepted until now as most true has come to me through my senses. But occasionally, my senses deceive me. It is unwise to trust completely those who have deceived us even once.

But I am still here, sitting by the fire, wearing a winter dressing-gown, etc. How can I doubt these?

Another example: how can I doubt that these hands or this whole body are mine?

To doubt such things I would have to liken myself to brain-damaged madmen who are convinced they are kings when really they are paupers. Such people are insane.

Often in my dreams I am convinced of such familiar events – that I am sitting by the fire in my dressing-gown – when in fact I am lying undressed in bed!

This discovery makes me feel dizzy. It reinforces the notion that I may be asleep!

Suppose then that I am dreaming – it isn’t true that I, with my eyes open, am moving my head and stretching out my hands. Suppose, indeed that I don’t even have hands or any body at all.

Still, the visions that come in sleep are like paintings. They must have been made as copies of real things. This leads to at least these general kinds of things:

  • eyes
  • head
  • hands
  • the body as a whole

These must be real. Even when painters paint sirens and satyrs with the most extraordinary bodies, they simply jumble up the limbs of different kinds of real animals, rather than inventing natures that are entirely new.

If they do succeed in thinking up something completely fictitious, at least the colours used in the picture must be real. Similarly, although these general kinds of things – eyes, head, hands and so on – could be imaginary, there is no denying that certain even simpler and more universal kinds of things are real. These are the elements out of which we make all our mental images of things – the true and also the false ones.

These simpler and more universal kinds include body, shape, their quantity, size and number, the places things can be in, the time through which they can last, etc.


  • physics, astronomy, medicine, and all other sciences dealing with things that have complex structures are doubtful
  • arithmetic, geometry and other studies of the simplest and most general things – whether they really exist in nature or not – contain something certain and indubitable.

For whether I am awake or asleep:

  • 2 + 3 = 5
  • a square has only four sides.


For many years, I have been sure that there is an all-powerful God who made me.

How do I know that he hasn’t brought it about that there is no earth, no sky, nothing that takes up space, no shape, no size, no place, while making sure that all these things appear to me to exist?

Anyway, I sometimes think that others go wrong even when they think they have the most perfect knowledge; so how do I know that I myself don’t go wrong every time I add two and three or count the sides of a square?

Well, you might say·, God would not let me be deceived like that, because he is said to be supremely good.

But, I reply, if God’s goodness would stop him from letting me be deceived all the time, you would expect it to stop him from allowing me to be deceived even occasionally; yet clearly I sometimes am deceived.

Some people would deny the existence of such a powerful God rather than believe that everything else is uncertain.

If there is no God and theology is fiction, then it means that I am a product of:

  • fate or
  • chance or
  • a long chain of causes and effects.

But the less powerful they make my original cause, the more likely it is that I am so imperfect as to be deceived all the time – because deception and error seem to be imperfections.

Having no answer to these arguments, I am driven back to the position that any of my former beliefs can be doubted.

I don’t reach this conclusion in a flippant or casual manner, but on the basis of powerful and well thought-out reasons.

So in future, if I want to discover any certainty, I must withhold my assent from these former beliefs just as carefully as I withhold it from obvious falsehoods.

It isn’t enough merely to have noticed this, though. I must make an effort to remember it.

My old familiar opinions keep coming back. Against my will, they capture my belief.

It is as though they had a right to a place in my belief-system as a result of long occupation and the law of custom. It is true that these habitual opinions of mine are highly probable; although they are in a sense doubtful, as I have shown, it is more reasonable to believe than to deny them. But if I go on viewing them in that light I shall never get out of the habit of confidently assenting to them. To conquer that habit, therefore, I had better switch right around and pretend (for a while) that these former opinions of mine are utterly false and imaginary.

I shall do this until I have something to counter-balance the old opinion. This will affect only how I acquire knowledge and not how I act.

I shall suppose that some malicious, powerful, cunning demon has done all to deceive me. I shall think that the sky, air, earth, colours, shapes, sounds and all external things are merely dreams that the demon* has contrived as traps for my judgment.

*Superphysics Note: In Hinduism, this is Maya

I shall consider myself as having no hands or eyes, or flesh, or blood or senses, but as having falsely believed that I had all these things.

I shall stubbornly persist in this train of thought. Even if I cannot learn any truth, I shall be on my guard against accepting any falsehoods, so that the powerful deceiver will be unable to affect me.

Like a prisoner who dreams that he is free, my laziness starts to suspect that it is merely a dream. It wants to go on dreaming rather than waking up. This makes me content to slide back into my old opinions.

I fear being shaken out of them because I am afraid that my peaceful sleep may be followed by hard labour when I wake in struggling in the imprisoning darkness of the problems I have raised.

Latest Articles

How to Fix Ukraine
How to Fix Ukraine
The Age of the Universe
The Age of the Universe
Material Superphysics
The End of Capitalism (and Marxism)
The End of Capitalism (and Marxism)
The Elastic Theory of Gravity
The Elastic Theory of Gravity
Material Superphysics

Latest Simplifications

Nova Organum by Francis Bacon
Nova Organum by Francis Bacon
The Analects by Confucius
The Analects by Confucius
The Quran by The Prophet Mohammad
The Quran by The Prophet Mohammad

All Superphysics principles in our books

The Simplified Series

Developing a new science and the systems that use that science isn't easy. Please help Superphysics develop its theories and systems faster by donating via GCash