My last bout of metablogging for a while, I promise.When blogging in the realm of political ideas, the temptation is to not allow one’s pristine thoughts to be befouled with the graffiti of passers by. The more partisan or idealistic a post, the more likely the resultant comments will cancel out your efforts through ridicule, parody, or even worse, a good point. Complete strangers might decide the one thing they have in common with each other is that they disagree vehemently with you, and then discuss at great length, in comments appended to your post, exactly why. And you might feel obligated to issue line-by-line rebuttals, lest your devotees get all confused and don’t know what to think anymore.

That’s the nightmare scenario I imagine plays in the minds of policy wonk bloggers who decide against allowing commenting when they start blogging. Sure, if you’re any good, you’re likely to have thought more about the issues than a great many of your readers (which is hopefully why they read you), and some of them might comment without ever getting the gist of your writings; others might never see past their assumptions about your motives; but the worst, probably, is people who spring to your defense with frankly terrible arguments, of which there are plenty on any side of any issue.

Allow commenting and you lose the ability to completely control the polemic on your site. Ideas you disagree with, for good reason, will likely get an airing on your blog and on your dime.

But I think this is entirely for the good, for several reasons:

1. Exposure: If you believe your ideas are better than the competition, then comment banter is your friend, because conversations do a better job at convincing than monologues. Every direct comparison should come out in your favor, if you’re any good at arguing your point.

2. Adaptability: Comment feedback can help you tailor your message to your audience. Are people letting you know they are stumped by a counterintuitive step in your reasoning? You’ll know to explain it more clearly.

3. Inoculation: Comments can show you where your thinking needs work. Ideas might indeed spark from individual genius, but they grow strong through all kinds of vetting — cooperative, constructive, competitive and even destructive. For new ideas to get good they need to be subjected to tests that help inoculate against fatal surpises later on in their memetic trajectories. Your commenters won’t let you down in this regard.

4. Ownership: You can’t stop people from discussing you and your ideas somewhere on the web, if they want to. Why not invite this discussion onto your blog, so you can keep a certain measure of ownership over it? This way you can delete the odd insult or wingnut, or close down comment streams that get out of hand, but not so much that your commenting community feels it needs to express their unfettered opinions somewhere else. It doesn’t really matter to others where these comments are located, though it might matter to you.

5. Authority & transparency: Readers of your blog who see it is possible to append comments to your writings will read you with the knowledge that you are open to corrections. This gives your writing added authority, as you are signalling your blog’s content is being peer reviewed with every read.

If there is a trend among probloggers and their commenting largesse it is this: Those bloggers who came to blogging after having made their name elsewhere (Andrew Sullivan, Juan Cole, Virginia Postrel, Johan Norberg, Dick Erixon, PJ Anders Linder) tend not to have comments, while those who made their name by blogging (Brad DeLong, Atrios, Kos, Yglesias, Gudmundson) do tend to allow comments. I think I know the reason for this: To many readers (and writers) still, reputations built in meatspace are a much harder currency than reputations built solely in the blogosphere. Published authors with public lives are perceived as far worthier targets by the fame-obsessed, and so the temptation to get a parasitic hearing in their comments section is likely to be more compelling.

When it comes to bloggers like Andrew Sullivan, the tide of insulting crap he would accumulate is more than enough reason for him not to bother with comments, I think. But for most other bloggers, I suspect these fears never materialize. And there are added mitigating factors to ponder:

You have a smart readership, and web pages can be infinitely long. Trust them to scroll to the diamonds in the rough and tumble of comment banter.

Ignored commenters always go away in the end. I’ve never seen this rule broken. It’s no fun if they don’t get a rise out of you.

Even so, are there half-way solutions? Yes — some bloggers do just trackbacks, or just link to a page on Technorati or Google showing pages linking to that post. In effect, this amounts to outsourcing the discussion and pointing the way there. This makes sense for blogs attached to organizations and companies, where a commenting free-for-all is problematic on legal grounds.

Others, like Andrew Sullivan, are generous in posting letters from readers. Boing Boing, too, posts vetted reader contributions. This saves money if your site is extremely popular, as allowing commenting can increase bandwidth costs by an order of magnitude. Some popular sites, like LGF and Kos, do manage with comments, though there might be some serious infrastructure money backing those blogs.

But not publishing or linking to reader feedback at all just makes you come across as a little disinterested in your readership, while the only effect in terms of the online debate is that you raise the barriers to entry — not everyone has a blog. And yet, you no longer “own” the means of comment production on the web, as anyone can set up www.[your name here]-watch.com, over which you have no control at all. (I know of one such site in Sweden.) Allowing comments helps preëmpt such occurrences.

In the end, of course, your blog is your free speech zone, not anyone else’s. But purely in terms of effectiveness, I think comments enhance rather than hinder debate.