Here is a revised version of Descartes’ cogito ergo sum (I think, therefore I am).
1. If x being is thinking, then x being exists
2. x being can include being a human being
3. x is thinking
4. Therefore, x exists
5. I am that x
6. Therefore, I am thinking (3,5)
7. Therefore I exist (4,6)
I haven’t checked whether the argument is valid. If it’s not please feel free to revise it.
Premise 1 is obvious if not self-evident
Premise 2 seems axiomatic
Premise 3 just takes some potential grasping of the concept but then will be accepted
Premise 5 might be where we run into trouble. Am I simply a bundle of an object? Is there no self or I? Am “I” just an external “me”? Well it seems perfectly reasonable to accept that premise 5 is more plausibly true then not. And if that’s the case then the conclusion is guaranteed: I exist.