> Twitter without downvotes is, after all, famously not a single train of thought under a Tweet!

In my experience, it really isn't! Whenever I see a bad take on Twitter, I generally see some sort of rebuttal within the first dozen or so replies. If you expand that rebuttal, you start to see some argumentation, which to me is the interesting part of Twitter.

I think part of what makes HN's downvote system viable is that it's a well-defined community, you need a lot of karma relatively speaking to unlock the downvote privilege, and in practice comments are only downvoted if they are off-topic or poorly articulated.

In that same vein Stack Exchange's downvote system works well too, because karma (rep) is tracked individually per-community and you likewise need a certain amount of it to unlock the downvote privilege. This makes it so that on SE and HN alike, the people with some seniority in the community are the ones to help dictate what should be surfaced by the site.

On Twitter though, it's liable to turn into the same mess Reddit has. Because there is no hard line between different communities, you can't have a meaningful per-community karma limit for the downvote privilege. This eventually devolves into a free-for-all where users brigade other subreddits (and on Twitter, other users' feeds) to mass downvote opinions they disagree with, no matter how articulate or well-sourced they are.

> it's liable to turn into the same mess Reddit has

Reddit has its problems but the idea that it’s somehow worse than Twitter is laughable.

Even with vote brigading subreddits are moderated and so actual content brigading is much rarer. Can you say the same about Twitter?

To me they have the ability to be equally as bad (and this is coming from someone who see’s the negative view of social media as overblown). What makes Reddit a bit more dangerous is their higher technical ability to do damage as opposed to Twitter social ability. In my opinion Reddit is more susceptible to hive mind theatrics since the site is specific designed with communities/groups in mind. You can bookmark a subreddit page and spend your entire experience on that subreddit. Twitter makes that a bit difficult as, while you can choose who you can follow, you cannot choose what the people you follow tweet, retweet, reply to which will inevitably expose you to different views and vice versa.

You can try to build a bubble on Twitter but something will inevitably slip in.

Maybe we're in different bubbles, but my experience with bad takes on Twitter is that the entire first level is mockery and quote-tweets, with people doubling down on that mockery in the responses to the quote-tweets. Rebuttals, if they come, happen mostly on locked down accounts or via subtweeting (although mockery is also standard in the subtweets).

I also don't think that up/downvotes are likely to change that for Twitter, since Twitter's culture is essentially built around bull sessions[1]. A key part of socializing during bull sessions is mockery, and getting buy-in from your group to perform mockery/ragging on another person in then group (who is supposed to gracefully accept said mockery).

[1]: https://www.urbandictionary.com/define.php?term=bull%20sessi...

HN also has moderators who can step in when things look like they're getting out of control which really helps. Or in some cases just point people to the rules and tell them to stop causing flamewars or get out.

It really makes a difference to the overall discourse. Something that is missing on most other places on the web!

HN moderation for those of us who have been here longer than some posters have been alive, this place is a lot different than it used to be, and moderation now tends to stifle conversations that in the past would have spawned great conversations that remained civil. Dang and friends do their best but for the most part the community is better off self censoring and exploring ideas and concepts without guidance and supervision. Unfortunately as more people flock to a gold rush a tragedy of the commons occurs and the site starts to see dang and team as absolutely necessary for each discussion when frankly they shouldn't be obviously seen guiding discussion.

The quality of the downvotes depends on the quality of the community, though, and the HN community is a lot higher quality than Twitter.

The size of community contributes also. Twitter has a very broad and huge community comparing to HN one.

HN restricts down voting to users above a certain point count, which really improves the quality of that signal