What should be the criteria for one person answering the same question twice?

Question

There are two answers to this recent question by the same person

How to find underground resources (water? caves?) on Mars?

He could have edited what he added to his previous answer. For whatever reason, he instead answered again. The second answer has a different theme and I suppose could stand alone.

But then I think... so, if people figure they can answer twice as long as there is enough to distinguish the two responses as genuinely different, can that be gamed? And would people game it?

And maybe it helps keep the page shorter if everything a person wants to say is in one answer.

What do you think?

Answer 1

I had just been writing "Perhaps Brian himself will chime in with his reason(s)" when his answer appeared.

I think the system works well the way it is. One this site and the others that I frequent, multiple answers are rare (I recall noticing only three in the many thousands of posts I have read). The reasons for posting multiple answers could be

• Is this answer different to the other answer?
  It could be that the author has completely changed their mind (not the case here I think). In the current case the second answer is different enough.

• Does the other answer have history that could be invalidated by updating it?
  This could have been used by Brian (but he does not report that) because the previous answer was accepted. In another case I have seen extensive pro and con commentary that would be invalidated by an update.

Could it gamed? How would that work? One might imagine that multiple answers might give the author more votes, and it works in the cases I have seen because the answers were different. And that's OK.

But if a person posts an answer that is very similar to a previous answer, users often vote it down, regardless of the author. To me, this is the key. The community rewards the behavior it likes, punishes behavior it doesn't.

So my conclusion is that there is no need for change.

Answer 2

I wondered about that myself when I put the answer. There is a pop-up from SE that discourages you from doing this and asks "are you sure?". I concluded, as I you noted, that the two answers were different. I felt, that adding the newer piece of information was sufficiently distinct from my earlier answer that it could stand alone.

People could then comment and vote on each one separately. That was my thinking anyway.

I was also tempted to add a comment to that effect, but decided not to, to discourage discussions in the comments which are better on meta.

Answer 3

I think I've also posted two different answers to a question perhaps two or three times as well, when the questions were difficult or challenging or there was considerable discussion over time, and in each case the answers were substantially different. I think as long as it is done rarely and is done for a specific purpose it's okay.

I'm certain that I've never seen a case where I felt that someone was doing it to "get points" or to make mischief. When people do it it's always seemed to be for genuine organizational reasons, the two answers were so substantially different that it seemed to just make sense to be separate posts.

Readers may agree with one and disagree with the other, and so separate postings allows the two different approaches to be voted on separately.

Answer 4

I've written plenty of answer-posts with two or more answers. In general, this is the best way to go. However, I can recall one question where I posted two answers, using two very different approaches to the same question.

I submitted two answers to the question "Emergency Spacesuit Protection?", asking about what protection spacesuits provide against explosive decompression. The first answer is the "real-life" answer, the second answer is a plausible "Hollywood" scenario. Because the nature of the two answers were so different, and because both answers were fairly long, I put them in separate posts.

Both the question and my first answer had a few upvotes. My second answer had no votes at all.

This was a special case, and in general one shouldn't post twice.