Self assertion

[deferro]

How, or why is it we can assert individually "I exist"? Descartes considered this problem wasn't answerable or perhaps didn't understand it like we (think we) do now.
Can an individual assert "I am, therefore, I think"? Who asserts thought, in that case, or where do thoughts occur and why?

We assert that individuals thought of things, or discovered otherwise hidden structures in nature, which have always been there. But no single individual can "think by themselves", the will to think comes from our collective "duty" to do so, as Spinoza would have er, thought of it.

 

[Math Is Hard]

How, or why is it we can assert individually "I exist"? Descartes considered this problem wasn't answerable ..

I don't understand why you say that. The "cogito" was his answer. In Meditations, he said that he was, without doubt, a "thinking thing". No matter what deceptions he encountered through his senses, there still had to be something that existed that was being deceived. Such a nice argument you wonder why someone didn't think of it before <cough> like St. Augustine </cough>.

..or perhaps didn't understand it like we (think we) do now.

How do we understand it now? (Or think we do?)

 

[deferro]

He said that he could say thought was: (within a complete notion of "identity") that he had been thunking.
Which paradoxically implies that we do not think we are, we thought we were, in fact thinking when we thunked it.

"We" understand the same problem today as measurement, which is paradoxical (see EPR, Bell, ...).

 

[Russell Berty]

We can assert individually that “I exist” as well as “thinking exists.” But our assertions may not be valid.

“Thinking exists” is an extremely reasonable assumption.

However, “thinking exists” is not known to be true beyond all possible doubt.

Playing the skeptic game is very useful but it will never end on its own. We could go on and on, doubting anything we claim. At some point we need to stop playing the skeptic game so that we can build up a theory (or philosophy) of reality. The skeptic game has no end, so we choose to end it. Whatever claims have survived our attacks thus far, we will use as our basis for building our philosophy. “Thinking exists” or even “sense-data exists” is a very fundamental place to start. One would also include some sense of “I exist” and we would also want “memory exists” of some sort. None of these assumptions are provable. To see this, just resume the skeptic game. But if our goal is to derive a theory of reality, we need to start somewhere. So, in the end, the assumptions listed above are extremely reasonable to believe true. “Reasonable” meaning we do not seem to run into any problems (most importantly in our daily lives) by assuming they are true.

However, the assumptions are still not known to be true beyond all doubt.

There is also a psychological hump to overcome. It can be very disquieting to think that we have no such thing as absolute certainty - that we cannot claim something is known beyond all possible doubt. So, many people will fight this notion, continually trying to argue that they have some absolute proof (say of the claim “I exist” or “god exists” or “1+1=2”.) One needs to realize that not having knowledge that is beyond all doubt is not harmful to us. For example, there was a time in everyone’s life when they surely had no knowledge of what “certainty” or “formal proof” meant. When someone is 1 years old, they get along just fine without needing to know absolute truth and definitely without being able to argue the existence of absolute truth.

Our assumptions are extremely reasonable but not beyond all doubt. And this is good enough for us to live our lives by. How certain can you be that this is good enough? You can be extremely reasonably certain that it is good enough (not beyond all doubt, but still reasonably certain.)

 

[davee123]

“Thinking exists” is an extremely reasonable assumption.
However, “thinking exists” is not known to be true beyond all possible doubt.

I think the caveat is that we're defining existence. Personally, I think we define existence as that which we conceive of. Further, there's a level of physical existence which is defined as that which we can physically perceive. The difficult part is that because thought isn't necessarily consistent, and appears to differ between beings which we believe can think, we don't know if existence has any consistency outside of our thoughts. That is to say, if my thought did not think about X, would X still exist in some manner? And if I were then to think about X, would X still be unaffected by the fact I had thought of it?

From a physical perspective, existence is also fuzzy, even as we understand it. "The book" isn't really "a book". There's a non-distinct line we imagine as being "the book" and "not the book". But that line doesn't exist in reality. Which specific sub-atomic particles are part of "the book"? How can you delineate one distinct "thing" from another "thing"? Really, you might as well simply say "perceptions exist". But the fact that your thought attempts to interpret those perceptions as somehow being informative rather than simply sensational is merely an assumption.

The end result is that perceptions happen to be a good predictor, as does the thought process that attempts to interpret the perceptions into an understanding of something "external" to yourself. Hence, we use that predictor because it's the best (and possibly only) tool we have, and we prefer using it to not using it.

As a result, thought and perception are known to exist, effectively by definition. Everything else's existence relies on the assumption that our perceptions actually dictate something about other things that exist.

DaveE