His famous skepticism,is still a useful tool, but his conclusion, is, like all conclusions, fatal to real progress. Recall that Descartes wondered, how can I determine reliable knowledge, and he decided to doubt everything he could. The story we know is that he found one undeniable thought; "I think, therefore I am."
This was the exact point at which Descartes could have leveraged his consciousness into an area where vision was possible, the glints we all live with, could have been sustained a bit longer, but with his motto, I think therefore I am, he put a skull and crossbones sign, right at the mental geographical point where in fact, any sign should read: "come on in, the water's glorious."
Because you have to keep pushing, and the glimpse that our verbal apparatus is but a mechanical contraption, not even designed to pursue knowledge, but rather just rearrange the external world, is a good step. But it was foreclosed to Descartes, who put himself, right in the way of a clear view. He trusted in words, when he was close to getting beyond them.
The mind, the ordinary mind, in the presentation Jan Cox used once, is a burglar, who, when the householder is roused to investigate a break-in, the burglar then puts his arm around the shoulders of the householder and says, "where, we'll find him, where could he be?"
A resolute skepticism is a useful tool, take a thought, any thought that crosses your attention, say a thought like:" I love you, Tom Kelly." There is a landscape beyond the words, you have to try to look through the sentence train.
I think therefore I am, how reliable is that? No "I", no "think", might have allowed a glimpse of "am,"
But not for Renny. He still gets a halo for the tools of skepticism though. And now that I put this together, what if, Descartes meant that sentence, dada, I am, as a joke. A joke he was sure the right people would get. After all, it is manifestly absurd, to someone advertising they will doubt everything. Really, I think I just got the philosopher's joke. It's on me.