By formulating the Cogito, Descartes was implicitly espousing the view that mind exists independently as something distinct from, and different from, matter. Where he ran into problems was when he tried working his way back from the mind's reality to the reality of anything else.
Nowadays, we have come to expect thrillers where we do care about the device that drives the plot -- not least because said device represents a credible threat to our nation, our way of life, or, best of all, our whole world.
When I began writing military thrillers I was eager to use my past experiences to breathe some realism into a genre I felt was sorely in need of it. I quickly found out that it was a double-edged sword.
Writers have limits when it comes to the amount of violence they'll tolerate in fiction. This is because in order to write a scene, a writer not only has to put themselves inside the action, they have to go deep inside their characters' heads.