External reality
Descartes proved he was here with "I think--therefore I am," but how would he have proved that he wasn't alone? Did he ever address that? And if he did, might he have said something like "I can't wholly control you, our suroundings, or our circomstances--therfore external forces and/or individuals exist"? Does that work? Or can anyone come up with a better axiom?
Comments (16)
Descartes did not prove he existed. He found something he concluded could not be doubted, that is, that he existed. He could not doubt it because he would have to exist in order to doubt. It does not follow that there is anything else that is indubitable.
But his real concern was to establish the foundations of knowledge, not to eliminate doubts that he did not have.
I am thinking (Minor premise).
Whatever thinks, exists (Major premise).
Therrfore I exist (Conclusion.)
Now, how do I prove that you exist?
That the room I'm sitting in, the country I live in, the world this country is part of, and the sun I saw today exist?
The argument you presented for your existing cannot be utterly private without losing all meaning. Membership of a community is implied by your use of language.
I am aware of many things
There are things that are not me (as in, I am aware I am different from them)
There are things that think which are not me, and which I am aware of
Whatever thinks, exists
I know they think because I interact with them, and I am not the interaction itself but a participant (I am aware I am different from the interaction) I interacts.
Minor premise: Things of my making are less than I am.
Major premise: Things that are less than I am are in my control.
Conclusion: Therefore anything (and anyone) that exists outside my control is not of my making.
Would that prove I have my own independent existence?
Now would you specifically be able to know if they were thinkers? If your definition of "I" never expanded from, "the thinker that knows its thinking", then you could not. And Descartes wasn't leaving it at that either. His goal was simply to start with a foundation to build other knowledge from.
So, we could try a few ideas ourselves. We can't see in other people's heads to know if there is an I there right? Typically though we expand the definition of I to include other aspects of ourself. If a thing matches enough of those, we say, "That's a thinker too." Basing off of Descartes initial line of thinking, where would you go from there to prove that I exist for example?
I start by assuming that there is nothing external to my mind.
I have read and appreciated the greatness of Don Quijote, but cannot write a sequel of equal greatness.
As I was able to write Don Quijote in the past, but am not able to write a sequel, something must have changed.
My first supposition is that something has changed in my mind.
But then I read Great Expectations, which I know I must have written, appreciate its greatness but am still not able to write a sequel.
As it seems that nothing has changed in my mind, I can only conclude that something has changed outside my mind, concluding that I am not alone.