As I see it, blogging is all about fostering conversation, so feel free to comment on any post, no matter how old. I do not moderate comments and welcome respectful criticism (or praise!), but I do use a spam filter that occasionally eats legitimate comments. Usually this is because the comment includes more than two links, or uses certain trigger words. If you get caught in the filter by mistake, try reposting or send me an email and I'll check the filter (see the About post for my address); I'll approve anything that isn't spam or blatantly disrespectful.
Also note that I reserve the right to modify existing posts to remove typos, clarify my point or improve my style, with or without notice, but significant corrections will always be marked as such. Unlike some bloggers, I will never delete a post to hide my errors, but just because something is posted here does not necessarily mean I still agree with it. In the seven years since I started this blog, my views have changed in many ways--not least due to the very discussions we have had here.