De omnibus dubitandum

Some years ago I was struck by how many false things I had believed, and by how doubtful was the structure of beliefs that I had based on them. I realized that if I wanted to establish anything in the sciences that was stable and likely to last, I needed – just once in my life – to demolish everything completely and start again from the foundations. It looked like an enormous task, and 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 have no excuse for going on planning to do it rather than getting to work. So today I have set all my worries aside and arranged for myself a clear stretch of free time. I am here quite alone, and at last I will devote myself, sincerely and without holding back, to demolishing my opinions.

Whatever I have accepted until now as most true has come to me through my senses. But occasionally I have found that they have deceived me, and it is unwise to trust completely those who have deceived us even once. Yet although the senses sometimes deceive us about objects that are very small or distant, that does not apply to my belief that I am here, sitting by the fire, wearing a winter dressing-gown, holding this piece of paper in my hands, and so on. It seems to be quite impossible to doubt beliefs like these, which come from the senses. 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, or say they are dressed in purple when they are naked, or that they are pumpkins, or made of glass. Such people are insane, and I would be thought equally mad if I modeled myself on them.

As if I were not a man who sleeps at night and often has all the same experiences while asleep as madmen do when awake – indeed sometimes even more improbable ones. Often in my dreams I am convinced of just such familiar events – that I am sitting by the fire in my dressing-gown – when in fact I am lying undressed in bed! Yet right now my eyes are certainly wide open when I look at this piece of paper; I shake my head and it isn’t asleep; when I rub one hand against the other, I do it deliberately and know what I am doing. This wouldn’t all happen with such clarity to someone asleep. Indeed! As if I didn’t remember other occasions when I have been tricked by exactly similar thoughts while asleep! As I think about this more carefully, I realize that there is never any reliable way of distinguishing being awake from being asleep.

Rene Descartes — Meditations on First Philosophy in which are demonstrated the existence of God and the distinction between the human soul and the body

Life in the Woods

I had this advantage, at least, in my mode of life, over those who were obliged to look abroad for amusement, to society and the theatre, that my life itself was become my amusement and never ceased to be novel. It was a drama of many scenes and without an end. If we were always, indeed, getting our living, and regulating our lives according to the last and best mode we had learned, we should never be troubled with ennui. Follow your genius closely enough, and it will not fail to show you a fresh prospect every hour.


Time is but the stream I go a-fishing in. I drink at it; but while I drink I see the sandy bottom and detect how shallow it is. Its thin current slides away, but eternity remains. I would drink deeper; fish in the sky, whose bottom is pebbly with stars. I cannot count one. I know not the first letter of the alphabet. I have always been regretting that I was not as wise as the day I was born.

Henry David Thoreau – Walden or Life in the Woods

Starting Point

For a common man, the independent existence of the world outside the mind, and thus the existence of the glowing sun, hard ground, cold water and the like, is beyond the slightest doubt; he holds this as the unshakable truth. It is enough, however, only to think for a while, to see that there is something even more certain, namely, that there is my own consciousness, because if it were not so, I would know nothing about the material world. Enough is to pronounce this sentence to be immediately convinced that my own consciousness can be the only appropriate starting point for any philosophical speculation. It is amazing that so many centuries had passed before people managed to understand it. Only Descartes with his famous cogito, ergo sum considered the consciousness as the starting point.

Consider the first manifestation of our consciousness. The first of its content can be, of course, nothing but a feeling of a different kind: the feeling of light, sound, pain, pleasure, etc. These feelings come to consciousness, go out of it and change without our complicity. They are the only content of our mind; the content that presents itself to us not as something created by the consciousness, but as something imposed.

The consciousness then assumes that there is an external object, the presence of which is necessary to induce feelings. But this assumption of the existence of external objects, which apparently takes place without any consideration and thought, is actually a logical conclusion, without which we would never have come to know the outside world.

It is obvious therefore, based on the above analysis, that the material world can not be regarded as a collection of some real beings, independent of our mind, which could exist even when the mind did not think or imagine anything.

Adolf Eugen Fick – Die Welt als Vorstellung. Akademischer Vortrag