Whatever one does - thinking, feeling, etc. - one needs to exist first. So you can substitute cogito with whatever you like.<p>The question, on the other hand, is what does it mean to exist. Philosophers are obsessed with this question, epistemology.<p>Think about it... If I told you that an entire universe exists that you can never perceive or discover through any observations of the one you live in, in what sense does it exist vs not exist? If I replace the word exist With some made up word, will the sentence have any less meaning? It follows from this that existence seems to be defined in terms of perception of conscious observers. And in fact, consciousness and existence are inextricably linked. Philosophers cannot talk of existence without implying consciousness.<p>And the question begins anew -- what is the nature of this perspective from this world, from my body?