For example, as this continues, my estimate for how likely it is that Eugine was actually behind this has gone up from around 10% to around 50%,
Wow. I agree that E_N's silence is evidence they're ialdabaoth's downvoter (not least because E_N doesn't generally shrink from confronting people about being wrong) but I wouldn't peg it as having a likelihood ratio of 5. More like 1.2 or 1.5, maybe. The only strong bits of evidence pointing at E_N are these two points ialdabaoth made. The other things, namely
are much more slender evidence. The Eugine Dunnit Hypothesis does seem to tie all of that evidence together nicely, but maybe that's confirmation bias. I'd better try thinking of contrary evidence:
Not sure what to make of it all.
for example if Eugine had responded quickly he could have simply made his votes public which one can do from preferences as I understand it.
I might be wrong (I don't use that feature) but I think that only makes votes on top-level posts public. (Though that information would still be suggestive.)
Edit: aaaand I only just saw your reply to TheOtherDave.
a priori I'd have expected E_N to be less likely than average to go on a downvoting rampage; my mental model of E_N simply argues with people it disagrees with, rather than pulling some cloak-&-dagger shit
I agree strongly here. That's part of why my initial estimate was low. My initial estimate was based on the fact that there were around 5-6 users with enough karma and the apparent political motivation, and then I reduced that percentage for Eugine because he seemed unlikely to be the sort of person who would do something like this.
...I've disagreed
I'm just tired of the signal pollution, and would like to be able to use karma to honestly appraise the worth of my articles and posts, without seeing 80% of my downvotes come in chunks that correspond precisely to how many posts I've made since the last massive downvote spree.
EDIT to add data points:
Spurious downvoting stopped soon after I named a particular individual (not ALL downvoting stopped, but the downvotes I got all seemed on-the-level.)
One block of potentially spurious downvoting occurred approximately one week ago, but then karma patterns returned to expected levels. I consider this block dubious, because it reasonably matches what I'd expect to see if someone noticed several of my posts together and disagreed with all of them, and did not match the usual pattern of starting with the earliest or latest post that I had made and downvoting everything (it downvoted all posts in a few threads, but not in other threads), so I'm just adding for completeness.
Spurious, indiscriminate downvoting started up again approximately half an hour ago on Sunday (12/1/2013), around noon MDT.
Edit: And now on Tuesday, 12/3/2013, at 10 AM, I'm watching my karma go down again... about 30 points so far.
Edit: And now on Saturday, 12/14/2013, at 2 PM, I'm watching my karma go down again... about 15 points so far, at a rate of about 1-2 points per second.