Evidently, I exist.
In fact, I KNOW I exist.

Evidently, you exist.
But I don't KNOW that for sure.

Why? Because I think. I think, therefore I am. (no idea where that comes from, but it's catchy)

But I don't know for sure of any existence past my mind. For all I know, I could be perpetually dreaming. You talk to me, but those might just be my own thoughts of what another person might say. Even surprises could be subconscious thoughts. I know I think, but I don't know for a fact that YOU do. I can hook you up to an EEG, but that could just be my brain thinking that you exist. Even if it were possible to share thoughts, I wouldn't know for sure because my brain might be thinking those thoughts. I don't know that you exist at all, but I believe you do, therefore you do in my mind. If you existed and I didn't think that, then you would not exist in my mind, and, as far as I know, you don't exist.

Senses are controlled and processed, ultimately, by the brain. My brain can tell me I'm touching something, but I don't know for sure that it is actually there. This means that I don't know that objects without a human brain exist, either.

Our perception past our own brains might be true, it might be a lie, or it might be a half-truth. Our brains fill in gaps in sensory information with our brains' best guesses. This happens all the time, eg. peripheral vision is mostly our brains' guess at the rest of the picture based on a little information from the edges of our vision. That is why you don't see much movement in your peripheral vision unless everything else in your vision is moving, even if something in your perceived range of vision is moving.

To sum it up: Existence is like quantum mechanics: both true and not true if not known for sure. I know I exist, but I don't know for sure that anything else exists, therefore you both exist and don't exist in my mind, and I both exist and don't exist in your mind (or what I believe is your mind). This is supported by the fact that our brains fill in the gaps of limited sensory information, causing perception.

Are you saying that to convince us that you do exist ? How could we trust in you because you say that you could believe that we don't exist ?

Moreover, how can you be sure that you really exist ? Isn't it an illusion ? As a case in point, AI in computer games have the illusion that they exist, but it is not true.

Quote from: mdr1 on May 13, 2013, 01:00:46 pm

Are you saying that to convince us that you do exist ? How could we trust in you because you say that you could believe that we don't exist ?

Moreover, how can you be sure that you really exist ? Isn't it an illusion ? As a case in point, AI in computer games have the illusion that they exist, but it is not true.

But AI does not think. It goes by a set of instructions. Even learning AI does not think, and, if it did, how would we know?

And who tolds you you think ? Who told you you are not a set of instructions ?

Cogito, ergo sum. That means "I think, therefore I am".
That 'catchy sentence' is a saying from Descartes, a philosopher who lived during the French Revolution (1789). It means that you can't trust anything unless you have checked it yourself, because you can trust your own sense (which is obviously not true, optical illusions etc)...

Descartes invented the Cartesian coordinate system, which is now the most common coordinate system in use.
And a lot more.

Class ended.

Evidently, I exist.
In fact, I KNOW I exist.

This particular bit of philosophy ("Cogito Ergo Sum") stems primarily from Descartes way back in the 17th century¹. Anyway, it's a bit of a tricky statement to make. For one thing, you need to prove that you have perception, which is quite obvious, but impossible to prove without a priori knowledge. More concisely, it's not entirely self-evident that an object which has the property of perception exists. Please excuse the connotations of the word "object" as a flaw of English and not a fundamental flaw in the counter-argument.

This extends to other things. As you mentioned, you really can't be sure of the reliability of your senses, a view called Solipsism. As Descartes argued that for all you know, a malicious entity he called the Evil Genius could be manipulating all of your senses to give you the illusion of an external world.

To sum it up: Existence is like quantum mechanics: both true and not true if not known for sure. I know I exist, but I don't know for sure that anything else exists, therefore you both exist and don't exist in my mind, and I both exist and don't exist in your mind (or what I believe is your mind). This is supported by the fact that our brains fill in the gaps of limited sensory information, causing perception.

Be very careful with making analogies to Quantum Mechanics, particularly with regard to interpretations of it. In this case, many physicists would vehemently argue that the notion of superposition of states is meaningless as an actual state. To use Schrodinger's cat, they would claim that speaking of the cat as either alive or dead is meaningless until you observe it to be so.

However, your point does have merit. I don't know if you realized this, but you can't encapsulate the notion of "partially true" in classical logic. It's neither solely True or solely False, just like a computer that can only represent 1 or 0. However, there are non-classical systems called fuzzy logics that have an entire sequence of values of "truthiness", just like a quantum computer has an entire range of values between 0 and 1.



¹ aeTIos, he had been dead for over a century by the time the French revolution occurred...

Although this may not be relevant, here's a short story about an AI that is seemingly sentient.
It's written by Issac Asimov: http://filer.case.edu/dts8/thelastq.htm

As a side note. I think we all exist. It's simpler that way. When we die or w/e, I'll figure out the rest then.

Question, how would people behave if the entire world was tool-assisted like in speedruns? Would people be able to run through walls without dying or do all sort of special tricks without hurting themselves too much?

Maybe all I see and hear is coherent optical illusions made by my brain. Maybe you guys don't even exist. Maybe nothing here exists and are just figments of my imagination. Maybe my entire life is a dream. Maybe something that "exists" is only limited to the realm of my imagination. So everything that exists exists to my point of view. Maybe you can even make exist something that doesn't exist, kinda like this thread I found one time, I don't remember what it's called, but it's akin to hypnosis (as in convincing yourself you're a pony or something), but you can hypnose yourself into convincing yourself your imaginary friend exists and he can even spawn more imaginary friends. (Also thinking God exists, but it's more religious matter and I don't really want to embark in this discussion. But it's pretty much in the same idea, if you want God to exist, then it exists for you (but don't shove its existence down the throats of others, they can believe it doesn't exist).)

Also AngelFish et al. I think you're pretty much challenging the concept of "thinking" with neural networks.