Is there any knowledge in the world which is so certain, that no reasonable man could doubt it?

Answer 1

Well according to Descartes its the knowledge that u exist . Just by the mere fact that if it is doubted it must be true because YOU are doubting it .
He nowhere goes to show that that thing that thinks (i.e. you) is a person, it can only be assumed as some sort of entity. Also does not prove the existence of other peopl/things.

Answer 2

Reasonable is a very flexible term. Biased almost. Opinionated. It calls upon one's personal perspective which therefore renders the questions answerable in all ways, both being correct and incorrect depending on the view viewing it. Unlimited possibilities with such a loophole. Personally I think all things are possible. Thus, I'd have to say yes. Although I'd take that with a grain of salt when compared to my true to heart belief about the nature of perception and what reality is to the human experience.

Answer 3

Probably not. Daniel Dennett (I think) has a clever little story about a guy whose brain is disconnected from his body and kept alive in a tank, but transducers at the brain's nerve endings communicate by radio with transducers at the corresponding nerves in the body. Dennett uses the situation to raise a lot of questions about personal identity. One can also ask, is there any way to tell that you aren't already a brain in a tank and that all your perceptions are fed to the brain by computer? If not, there's not much that can't be doubted.

Answer 4

That is such a subjective question.
I, for example, would say "global warming", "we are going to run out of fossil fuel in the next 30 years".
I'll bet an awful lot of people would disagree, but then I would accuse them of being unreasonable.
More widely accepted knowlege might include most of the mathematics and physics theorems, E = mc^2, sunlight takes 8 minutes to get here from the sun, the universe is expanding, etc.

Answer 5

Not that I can think of, but my thought is this: Doubt is not always a bad thing. If we go through life without doubting things, then we are not inclined to question and we are not inclined to learn. Some people who accept things as they are become stagnant in life and actually become so used to what they "know" that they don't try to learn anything anymore. For me, the day that I stop learning is the day that my life is over, no matter what it is that I may be learning about.

I'm not sure if that has much to do with your question, but it's what you made me think about :)

Answer 6

Oh yes. No reasonable man could doubt that every time you step foot into Washington DC, you lose 20 IQ points.

Answer 7

Walk on to a high cliff. Jump off, then doubt the existence of gravity. If you can do this, can you call yourself a reasonable man?

Answer 8

The only knowledge that is certain in the world is I am.
It is the only piece of knowledge that everyone knows - they only know that they exist

Answer 9

I used to think that about Newton's Laws of Thermodynamics but when I learned Einsteinian physics that blew that one up. I don't pretend to understand Quantum physics but that seems to indicate that no we can't rely on any kind of certainty.

Answer 10

love is the most powerful force on earth. whether it is love of a god, a person, pursuit of knowledge--it is the ultimate motivator and can be used for the most good or the most evil.