Reason for believing in the existence of the world What if we ask the opposite? What are the reasons to believe that I exist?
Before answering the last question, I consider that we must ask ourselves about the conditions for a statement like "I, Jhon, exist" to be true. If we assume that it is true, wouldn't it be equivalent for a future in which I am in fact already dead? That is to say: "I, John, exist" and "John existed" would be equivalent in the future, and if we accept the first statement as true we must necessarily also accept the last statement as true.
What does this mean? That neither perception nor self-awareness can establish the truth conditions for objective discourse. And this means that for the statement "I exist" to be true, the perception of myself is not a sine-qua-non condition of its truth and objectivity. Non-perception would be essential and a sine-qua-non for true and objective discourse.
And is not what we call the "external world" the domain of Non-perception, as what is not me, as the other, even as another subjectivity other than mine? This being said raises the question of the reasons for believing Whether or not the external world exists is a petitio principii – as long as we expect that the answer [whether affirmative, negative or inconclusive] can be true or false.
We give reasons for something to be true or false. And we hope that in a debate those reasons are valid no matter who utters them. If another person presents our reasons that we consider valid, we must necessarily say that they are also valid. Hence the truth about our existence or the existence of the "external world" does not necessarily depend on whether we perceive it or not. And on the contrary, the conditions of truth and objectivity seem to presuppose a world beyond my perception.