An hour, or until a reply--whichever comes firstI can't tell you pro-editing advocates how strongly I disagree. Editing posts serves no useful purpose whatsoever, once those posts have been read and replied to. Even a simple "clarification" after the fact can disrupt the flow of the discussion. For those who have already replied, it's too late--they replied to the original post, flaws and all. And for those coming in later trying to follow the train of thought of the thread, it only adds confusion. So who benefits? No one!
If you really have a change of thought, write a subsequent post with a retraction, clarification, apology, whatever. You can't "unsay" what you said, so don't even try. As Ott so eloquently put it in the now long-gone previous thread on this topic, "you can't unring a bell."
If it really is important and appropriate to edit a post, send a pm to a moderator. They'll make the change. No problem. (Even there, I would count on the moderator to read the replies to the post and consider carefully whether the changes could add confusion.)
If you are really concerned about what you post, take responsibility for it. Do us all a favor: Write it carefully, in an appropriate state of mind. Edit it for clarity before you post it--that's what the "preview" function is for. If you're not sure about it, save the post as a text file, and reconsider it in the morning. Read it again after you post it, within the time limit, and make any needed changes while you still can. Delete it if you want.
Once you're satisfied with what you've written, be prepared to live with it. You can clarify or retract later, in another post, if it turns out that people misinterpret you, or if you were just plain wrong. It's a discussion! Once it's been posted, it lives, and you own it. If you don't like that, don't post.
Consider yet another reason why some people have advocated editing--when you've written something hurtful or offensive to someone else, and you feel guilty later. Well, folks, I've got news for you. Once you've acted like an ass, deleting your post or revising it substantially doesn't alter the fact. You're still guilty. If the offended person, or anyone else, has replied to your inappropriate content, it is even more small of you to go back and try to pretend that you never wrote it. It's a lie! Live with it. If you owe someone an apology, be a grownup and apologize.
It would be great in life if every time we made a mistake we could go back in time and do it differently. But we can't. And an "edit" function on an Internet forum cannot change that! A written, archived forum is either a record of real discussions, or it isn't. As I see it, the only reason to record the discussion in the first place is, well, to record it. And that is a great thing! Revising past posts removes this singular benefit. We might as well just have all posts "evaporate" soon after they're written, like an oral discussion.
That's my case. I've heard a lot of others bemoaning the "freedom" that inability to edit takes away from us. Please make your case. There are many individual "freedoms" that civilized communities cannot tolerate. I maintain that this is one of them. But I would love to hear a good argument for the opposing point of view. If you make a great point and prove the flaws in my thinking, you may revise my beliefs. Prove me wrong, and I'll acknowledge it--with gratitude. But I promise NOT to ge back and revise my posts!
Thanks for reading!