fandomhigh | Practical Philosophy, Tuesday

Today, one would find Ender on the lawn with his legs beneath him, his implacable calm restored from where it had wobbled over the weekend.

"One day, sometime in the early 17th century, the French philosopher called René Descartes set himself to a nigh impossible task," he began. "He realized that over the years he had believed many things he had come to feel were false, and wondered how many more he'd come to dispute. And so he decided to be proactive about it. 'I needed — just once in my life — to demolish everything completely and start again from the foundations', he would later write. He feared that if he kept waiting for the right moment, he'd be too old to do it properly."

He reached for a bottle of water, unscrewing the cap. "Once he settled with the thought, he realized he didn't need to fundamentally disprove each of his opinions to do so. It would be a lot of work, and all he really needed was to somehow undo the foundation of each. ' So all I need, for the purpose of rejecting all my opinions, is to find in each of them at least some reason for doubt', he concluded. And so he began to dig down, further and further, finding reason to doubt the very fundamentals of his beliefs, and in the end, realized there was only one thing he could not disprove to some extent - that he existed, for as long as he thought about anything at all, he had to exist."

Ender's mouth curved. "Or as it's been phrased in the public imagination, 'I think, therefor I am'. But Descartes' experiment provides more food for thought than merely that. He challenges us to think about what undergirds our beliefs, to accept that they might not be correct. Humanity, at least, has a habit of questioning everything, except for their most intrinsic, most elementary convictions."

He took a sip. "Now I'm hardly foolish enough to believe we can dig down and upend yours in a single class," he said. "First of all, I would like you to think - and discuss - what you feel is one unshakable idea you have about the world and the self. Secondly, I would like to ask you to spend this week trying, if not entirely, at least a fraction of what Descartes did: to find a reason to doubt this idea. And we'll speak of it next week."