A subjective-objective question: How do you know that I exist?

[oldcatdave]

How do you know if you exist? Well…try hitting your thumb with a hammer while hanging a picture. You should get a definite answer to your question.

 

[Seaumas]

Cogito Ergo Sum.

 

[MindOverMatter2]

Hi,
How do you know that I exist?

I don’t know that you exist. Your existence is apparent to me because you express a particular kind of behavior and communicate a particular kind of information that is sufficiently related to and is synonymous with the behavior and insight of a mind. I am aware of this relationship because i have a mind. How do i know i have a mind? I think therefore i am.

I may not have metaphysical proof of your existence. But I accept that you exist because i have no rational basis to doubt your existence. I have no good reason to be skeptical of it.

 

[Shike]

I don’t know that you exist. Your existence is apparent to me because you express a particular kind of behavior and communicate a particular kind of information that is sufficiently related to and is synonymous with the behavior and insight of a mind. I am aware of this relationship because i have a mind. How do i know i have a mind? I think therefore i am.

Besides the cogito as expressed through Descartes philosophy, I agree with what you say (I’d rather take its formulation under St. Augustine who didn’t start with universal methodological doubt as to render it meaningless). But I would say, because of what you said, that I know you exist.

I may not have metaphysical proof of your existence. But I accept that you exist because i have no rational basis to doubt your existence. I have no good reason to be skeptical of it.

And this is my point. Not all knowledge is demonstrative metaphysical knowledge. One of Descartes problems was trying to fit experience through his preconceived mathematical mold.

The big irony is that although Descartes was all about mathematical certainty, the movement he helped push along, the scientific movement, doesn’t have mathematical certainty in the truth of its theories, however well-established, predictive, and useful they may be.

Here’s an oversimplification to illustrate: we observe that the sidewalk is wet. We postulate a theory that says little green men cause sidewalks to be wet; we also find that this theory is always (as far as we observe) able to tell us when the sidewalk is wet. But if we were to claim we now know with mathematical certainty the cause of wet sidewalks we would be wrong. All we know is that ‘if the theory is true, then sidewalks are made wet’. To say that the phenomena prove the theory with mathematical certainty is nothing other than to affirm the consequent. There may be other theories that explain the data.