Today's post, Fundamental Doubts was originally published on 12 July 2008. A summary (taken from the LW wiki):

There are some things that are so fundamental, that you really can't doubt them effectively. Be careful you don't use this as an excuse, but ultimately, you really can't start out by saying that you won't trust anything that is the output of a neuron.

Discuss the post here (rather than in the comments to the original post).

This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was The Genetic Fallacy, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.

Sequence reruns are a community-driven effort. You can participate by re-reading the sequence post, discussing it here, posting the next day's sequence reruns post, or summarizing forthcoming articles on the wiki. Go here for more details, or to have meta discussions about the Rerunning the Sequences series.