Kurtis Beavers, one of our designers, asked the community team about design decisions that encourage empathy. Paradoxically, I immediately identified one of the most reviled features on Stack Overflow: downvotes. People so dislike being downvoted that we have three separate Zendesk macros explaining the role of downvotes in our system. Many of the earliest feature requests were variations of "Force user to comment on downvote". Not many people seem to think downvotes encourage empathy.

And yet, they almost certainly do. As I wrote back in March, 2009:

The nice thing about down votes is that [they tend] to avoid getting personal. I can click a down vote for any reason and I don't need to tell you why. In Usenet, the best you can expect is a polite explanation of what you did wrong. Down voting makes SO nicer to bad answers and questions, not meaner. I can't think of a better way to show a user they made a mistake.

That's not exactly the most coherent argument. To put it more concretely, people tend to pick the path of least resistance. If I see a nonsensical post, I have a wide range of options on a Stack Exchange site:

• Down vote
• Flag
• Vote to close (if a question)
• Vote to delete
• Write a critical comment
• Write a scathing answer attacking the premise (if a question)

On many other sites, my only options are:

• Write a critical reply
• Do nothing

Most people on most sites do nothing but, perhaps, passively read the page. It's not a stretch to say only the most passionate people bother leaving feedback. For every person who comments, answers, edits or even votes on a Stack Overflow question, hundreds more view it. When a question is objectively bad as measured by downvotes, it's more common for people to go out of their way to vote, comment or edit the question to improve it. Invested users feel responsible to do something about content that doesn't fit on the site. Stack Overflow gives those users many options other than leaving an unhelpful comment.

In my experience, critical comments tend to cause the most animosity within a community. I don't really blame people for reacting poorly to criticism no matter how constructive. When I was answering a lot of questions on Stack Overflow, I remember getting comments from people pointing out that my code would break if there were spaces in a file name. My gut reaction was something along the lines of:

What sort of idiot puts spaces in their file names? Windows programmers?

This was particularly unfair because I was using Windows. So even when comments politely point out a real problem with a post, it hurts.

Downvotes also hurt. But in my (somewhat limited) experience, extra downvotes hurt less and less. More importantly, they cause me to make a calculation: do I still think my post is worth risking more downvotes or have I changed my mind? For instance, a few years ago on our Skeptics site I answered the question "Is there any verifiable historical and/or scientific evidence that Moses lived?" I get a downvote every six months or so and each time I reconsider my answer. So far, I've not changed anything substantial, but the downvotes really cause me to think twice. I also get the occasional critical comment, which I'm afraid I don't take very well. I'd rather have people express their disagreement with a simple anonymous vote instead.