"I think, therefore I am" means that, if you think you exist. But it can be argued but it's irrefutable. For example, you might say that you may be thinking or imagining that you are somewhere else that you may not be physically. You can think that you are somewhere else but physically you are not. The non-deniable part is that you think that you exist therefore you exist, meaning that if you think you are physicaly in the place that you are thinking. I know right crazy.