The evil Demon argument
- How ever I have for many years been sure that there is an all-powerful God who made me the sort of creature that I am. 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 thing appear to m 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 my self 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. Let us grant them - for purposes of argument - that there is no God, and theology is fiction. On their view, then, I am a product of fate or chance or 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 imperfection. having no answer to these arguments, I am driven back to the position that doubts can properly be raised about any of my former beliefs. I don't reach this conclusion in a flippant or casual manner, but on the basis of power 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, and 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 weight of old opinion, and the distorting influence of habit no longer prevents me from judging correctly. However far I go in my distrustful attitude, no actual harm will come of it, because my project won't affect how I act, but only how I go about acquiring knowledge.
- So I shall suppose that some malicious, powerful, cunning demon has done all he can to deceive me - rather than this being done by God, who is supremely good and the source of truth. I shall think that the sky, the air, the earth, colors, shapes, sounds and all external things are merely dreams that the demon has contrived as traps for my judgement. I shall consider my self 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; and even if I can't learn any truth, I shall at least do what I can do, which is to be on my guard against accepting any falsehoods, so that the deceiver - however powerful and cunning he may be - will be unable to affect me in the slightest. This will be hard work, though, and a kind of laziness pulls me back into my old ways.
- Like a prisoner who dreams, and wants to go on dreaming rather than waking up, so I am 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 labor when I wake, and that I shall have to struggle not in the light but in the imprisoning darkness of the problems I have raised.