What I’ve Learned from Hacker News (2009)

What I’ve Learned from Hacker News (2009)
What I've Learned from Hacker NewsFebruary 2009

Hacker News was two years
old last week. Initially it was supposed to be a side project—an
application to sharpen Arc on, and a place for current and future
Y Combinator founders to exchange news. It’s grown bigger and taken
up more time than I expected, but I don’t regret that because I’ve
learned so much from working on it.


When we launched in February 2007, weekday traffic was around 1600
daily uniques. It’s since grown to around 22,000. This growth
rate is a bit higher than I’d like. I’d like the site to grow,
since a site that isn’t growing at least slowly is probably dead.
But I wouldn’t want it to grow as large as Digg or Reddit—mainly
because that would dilute the character of the site, but also because
I don’t want to spend all my time dealing with scaling.

I already have problems enough with that. Remember, the original
motivation for HN was to test a new programming language, and
moreover one that’s focused on experimenting with language design,
not performance. Every time the site gets slow, I fortify myself
by recalling McIlroy and Bentley’s famous quote

The key to performance is elegance, not battalions of special

and look for the bottleneck I can remove with least code. So far
I’ve been able to keep up, in the sense that performance has remained
consistently mediocre despite 14x growth. I don’t know what I’ll
do next, but I’ll probably think of something.

This is my attitude to the site generally. Hacker News is an
experiment, and an experiment in a very young field. Sites of this
type are only a few years old. Internet conversation generally is
only a few decades old. So we’ve probably only discovered a fraction
of what we eventually will.

That’s why I’m so optimistic about HN. When a technology is this
young, the existing solutions are usually terrible; which means it
must be possible to do much better; which means many problems that
seem insoluble aren’t. Including, I hope, the problem that has
afflicted so many previous communities: being ruined by growth.


Users have worried about that since the site was a few months old.
So far these alarms have been false, but they may not always be.
Dilution is a hard problem. But probably soluble; it doesn’t mean
much that open conversations have “always” been destroyed by growth
when “always” equals 20 instances.

But it’s important to remember we’re trying to solve a new problem,
because that means we’re going to have to try new things, most of
which probably won’t work. A couple weeks ago I tried displaying
the names of users with the highest average comment scores in orange.

That was a mistake. Suddenly a culture that had been more
or less united was divided into haves and have-nots. I didn’t
realize how united the culture had been till I saw it divided. It
was painful to watch.

So orange usernames won’t be back. (Sorry about that.) But there
will be other equally broken-seeming ideas in the future, and the
ones that turn out to work will probably seem just as broken as
those that don’t.

Probably the most important thing I’ve learned about dilution is
that it’s measured more in behavior than users. It’s bad behavior
you want to keep out more than bad people. User behavior turns out
to be surprisingly malleable. If people are
expected to behave
well, they tend to; and vice versa.

Though of course forbidding bad behavior does tend to keep away bad
people, because they feel uncomfortably constrained in a place where
they have to behave well. But this way of keeping them out is
gentler and probably also more effective than overt barriers.

It’s pretty clear now that the broken windows theory applies to
community sites as well. The theory is that minor forms of bad
behavior encourage worse ones: that a neighborhood with lots of
graffiti and broken windows becomes one where robberies occur. I
was living in New York when Giuliani introduced the reforms that
made the broken windows theory famous, and the transformation was
miraculous. And I was a Reddit user when the opposite happened
there, and the transformation was equally dramatic.

I’m not criticizing Steve and Alexis. What happened to Reddit
didn’t happen out of neglect. From the start they had a policy of
censoring nothing except spam. Plus Reddit had different goals
from Hacker News. Reddit was a startup, not a side project; its
goal was to grow as fast as possible. Combine rapid growth and
zero censorship, and the result is a free for all. But I don’t
think they’d do much differently if they were doing it again.
Measured by traffic, Reddit is much more successful than Hacker

But what happened to Reddit won’t inevitably happen to HN. There
are several local maxima. There can be places that are free for
alls and places that are more thoughtful, just as there are in the
real world; and people will behave differently depending on which
they’re in, just as they do in the real world.

I’ve observed this in the wild. I’ve seen people cross-posting on
Reddit and Hacker News who actually took the trouble to write two
versions, a flame for Reddit and a more subdued version for HN.


There are two major types of problems a site like Hacker News needs
to avoid: bad stories and bad comments. So far the danger of bad
stories seems smaller. The stories on the frontpage now are still
roughly the ones that would have been there when HN started.

I once thought I’d have to weight votes to keep crap off the
frontpage, but I haven’t had to yet. I wouldn’t have predicted the
frontpage would hold up so well, and I’m not sure why it has.
Perhaps only the more thoughtful users care enough to submit and
upvote links, so the marginal cost of one random new user approaches
zero. Or perhaps the frontpage protects itself, by advertising what type of submission is expected.

The most dangerous thing for the frontpage is stuff that’s too easy
to upvote. If someone proves a new theorem, it takes some work by
the reader to decide whether or not to upvote it. An amusing cartoon
takes less. A rant with a rallying cry as the title takes zero,
because people vote it up without even reading it.

Hence what I call the Fluff Principle: on a user-voted news site,
the links that are easiest to judge will take over unless you take
specific measures to prevent it.

Hacker News has two kinds of protections against fluff. The most
common types of fluff links are banned as off-topic. Pictures of
kittens, political diatribes, and so on are explicitly banned. This
keeps out most fluff, but not all of it. Some links are both fluff,
in the sense of being very short, and also on topic.

There’s no single solution to that. If a link is just an empty
rant, editors will sometimes kill it even if it’s on topic in the
sense of being about hacking, because it’s not on topic by the real
standard, which is to engage one’s intellectual curiosity. If the
posts on a site are characteristically of this type I sometimes ban
it, which means new stuff at that url is auto-killed. If a post
has a linkbait title, editors sometimes rephrase it to be more
matter-of-fact. This is especially necessary with links whose
titles are rallying cries, because otherwise they become implicit
“vote up if you believe such-and-such” posts, which are the most
extreme form of fluff.

The techniques for dealing with links have to evolve, because the
links do. The existence of aggregators has already affected what
they aggregate. Writers now deliberately write things to draw traffic
from aggregators—sometimes even specific ones. (No, the irony
of this statement is not lost on me.) Then there are the more
sinister mutations, like linkjacking—posting a paraphrase of
someone else’s article and submitting that instead of the original.
These can get a lot of upvotes, because a lot of what’s good in an
article often survives; indeed, the closer the paraphrase is to
plagiarism, the more survives.


I think it’s important that a site that kills submissions provide
a way for users to see what got killed if they want to. That keeps
editors honest, and just as importantly, makes users confident
they’d know if the editors stopped being honest. HN users can do
this by flipping a switch called showdead in their profile.



Bad comments seem to be a harder problem than bad submissions.
While the quality of links on the frontpage of HN hasn’t changed
much, the quality of the median comment may have decreased somewhat.

There are two main kinds of badness in comments: meanness and
stupidity. There is a lot of overlap between the two—mean
comments are disproportionately likely also to be dumb—but
the strategies for dealing with them are different. Meanness is
easier to control. You can have rules saying one shouldn’t be mean,
and if you enforce them it seems possible to keep a lid on meanness.

Keeping a lid on stupidity is harder, perhaps because stupidity is
not so easily distinguishable. Mean people are more likely to know
they’re being mean than stupid people are to know they’re being

The most dangerous form of stupid comment is not the long but
mistaken argument, but the dumb joke. Long but mistaken arguments
are actually quite rare. There is a strong correlation between
comment quality and length; if you wanted to compare the quality
of comments on community sites, average length would be a good
predictor. Probably the cause is human nature rather than anything
specific to comment threads. Probably it’s simply that stupidity
more often takes the form of having few ideas than wrong ones.

Whatever the cause, stupid comments tend to be short. And since
it’s hard to write a short comment that’s distinguished for the
amount of information it conveys, people try to distinguish them
instead by being funny. The most tempting format for stupid comments
is the supposedly witty put-down, probably because put-downs are
the easiest form of humor.

So one advantage of forbidding
meanness is that it also cuts down on these.

Bad comments are like kudzu: they take over rapidly. Comments have
much more effect on new comments than submissions have on new
submissions. If someone submits a lame article, the other submissions
don’t all become lame. But if someone posts a stupid comment on a
thread, that sets the tone for the region around it. People reply
to dumb jokes with dumb jokes.

Maybe the solution is to add a delay before people can respond to
a comment, and make the length of the delay inversely proportional
to some prediction of its quality. Then dumb threads would grow



I notice most of the techniques I’ve described are conservative:
they’re aimed at preserving the character of the site rather than
enhancing it. I don’t think that’s a bias of mine. It’s due to
the shape of the problem. Hacker News had the good fortune to start
out good, so in this case it’s literally a matter of preservation.
But I think this principle would also apply to sites with different

The good things in a community site come from people more than
technology; it’s mainly in the prevention of bad things that
technology comes into play. Technology certainly can enhance
discussion. Nested comments do, for example. But I’d rather use
a site with primitive features and smart, nice users than a more
advanced one whose users were idiots or trolls.

So the most important thing a community site can do is attract the
kind of people it wants. A site trying to be as big as possible
wants to attract everyone. But a site aiming at a particular subset
of users has to attract just those—and just as importantly,
repel everyone else. I’ve made a conscious effort to do this on
HN. The graphic design is as plain as possible, and the site rules
discourage dramatic link titles. The goal is that the only thing
to interest someone arriving at HN for the first time should be the
ideas expressed there.

The downside of tuning a site to attract certain people is that,
to those people, it can be too attractive. I’m all too aware how
addictive Hacker News can be. For me, as for many users, it’s a
kind of virtual town square. When I want to take a break from
working, I walk into the square, just as I might into Harvard Square
or University Ave in the physical world.

But an online square is
more dangerous than a physical one. If I spent half the day loitering
on University Ave, I’d notice. I have to walk a mile to get there,
and sitting in a cafe feels different from working. But visiting
an online forum takes just a click, and feels superficially very
much like working. You may be wasting your time, but you’re not
idle. Someone is wrong on the Internet, and you’re fixing the

Hacker News is definitely useful. I’ve learned a lot from things
I’ve read on HN. I’ve written several essays that began as comments
there. So I wouldn’t want the site to go away. But I would like
to be sure it’s not a net drag on productivity. What a disaster
that would be, to attract thousands of smart people to a site that
caused them to waste lots of time. I wish I could be 100% sure
that’s not a description of HN.

I feel like the addictiveness of games and social applications is
still a mostly unsolved problem. The situation now is like it was
with crack in the 1980s: we’ve invented terribly addictive new
things, and we haven’t yet evolved ways to protect ourselves from
them. We will eventually, and that’s one of the problems I hope
to focus on next.



I tried ranking users by both average and median comment
score, and average (with the high score thrown out) seemed the more
accurate predictor of high quality. Median may be the more accurate
predictor of low quality though.


Another thing I learned from this experiment is that if you’re
going to distinguish between people, you better be sure you do it
right. This is one problem where rapid prototyping doesn’t work.

Indeed, that’s the intellectually honest argument for not discriminating
between various types of people. The reason not to do it is not
that everyone’s the same, but that it’s bad to do wrong and hard
to do right.


When I catch egregiously linkjacked posts I replace the url
with that of whatever they copied. Sites that habitually linkjack
get banned.


Digg is notorious for its lack of transparency. The root of
the problem is not that the guys running Digg are especially sneaky,
but that they use the wrong algorithm for generating their frontpage.
Instead of bubbling up from the bottom as they get more votes, as
on Reddit, stories start at the top and get pushed down by new

The reason for the difference is that Digg is derived from Slashdot,
while Reddit is derived from Delicious/popular. Digg is Slashdot
with voting instead of editors, and Reddit is Delicious/popular
with voting instead of bookmarking. (You can still see fossils of
their origins in their graphic design.)

Digg’s algorithm is very vulnerable to gaming, because any story
that makes it onto the frontpage is the new top story. Which in
turn forces Digg to respond with extreme countermeasures. A lot
of startups have some kind of secret about the subterfuges they had
to resort to in the early days, and I suspect Digg’s is the extent
to which the top stories were de facto chosen by human editors.


The dialog on Beavis and Butthead was composed largely of
these, and when I read comments on really bad sites I can hear them
in their voices.


I suspect most of the techniques for discouraging stupid
comments have yet to be discovered. Xkcd implemented a particularly
clever one in its IRC channel: don’t allow the same thing twice.
Once someone has said “fail,” no one can ever say it again. This
would penalize short comments especially, because they have less
room to avoid collisions in.

Another promising idea is the stupid
, which is just like a
probabilistic spam filter, but trained on corpora of stupid and
non-stupid comments instead.

You may not have to kill bad comments to solve the problem. Comments
at the bottom of a long thread are rarely seen, so it may be enough
to incorporate a prediction of quality in the comment sorting


What makes most suburbs so demoralizing is that there’s no
center to walk to.

Thanks to Justin Kan, Jessica Livingston, Robert Morris,
Alexis Ohanian, Emmet Shear, and Fred Wilson for reading drafts of

Comment on this essay.

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“Simplicity, patience, compassion.
These three are your greatest treasures.
Simple in actions and thoughts, you return to the source of being.
Patient with both friends and enemies,
you accord with the way things are.
Compassionate toward yourself,
you reconcile all beings in the world.”
― Lao Tzu, Tao Te Ching