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On Consensus and Humming in the IETF

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This is an older version of an Internet-Draft that was ultimately published as RFC 7282.
Author Pete Resnick
Last updated 2013-01-28
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Internet Engineering Task Force                               P. Resnick
Internet-Draft                               Qualcomm Technologies, Inc.
Intended status: Informational                          January 29, 2013
Expires: August 2, 2013

                  On Consensus and Humming in the IETF


   The IETF has had a long tradition of doing its technical work through
   a consensus process, taking into account the different views among
   IETF participants and coming to (at least rough) consensus on
   technical matters.  In particular, the IETF is supposed not to be run
   by a "majority rules" philosophy.  This is why we engage in rituals
   like "humming" instead of voting.  However, more and more of our
   actions are now indistinguishable from voting, and quite often we are
   letting the majority win the day.  This document is a collection of
   thoughts on what rough consensus is, how we have gotten away from it,
   and the things we can do in order to really achieve rough consensus.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on August 2, 2013.

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   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Lack of disagreement is more important than agreement  . . . .  4
   3.  Rough consensus is when all issues are addressed, but not
       necessarily accommodated . . . . . . . . . . . . . . . . . . .  5
   4.  Humming is the start of a conversation, not the end  . . . . .  6
   5.  One Hundred people for and five people against might not
       be rough consensus . . . . . . . . . . . . . . . . . . . . . .  8
   6.  Five people for and one hundred people against might still
       be rough consensus . . . . . . . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  Informative References . . . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 10
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10

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1.  Introduction

   Almost every IETF participant knows the aphorism from Dave Clark's
   1992 plenary presentation [Clark] regarding how we make decisions in
   the IETF:

      We reject: kings, presidents and voting.

      We believe in: rough consensus and running code.

   That is, we don't let a single individual make the decisions, nor do
   we let the majority dictate decisions, nor do we allow decisions to
   be made in a vacuum without practical experience.  Instead, decisions
   are made by (more or less) consent of all participants, and the
   actual products of engineering trump theoretical designs.  We don't
   require full consensus; that would allow a single intransigent person
   who simply keeps saying "No!" to stop the process cold.  We only
   require rough consensus: If the chair of a working group determines
   that a technical issue brought forward by an objector has been truly
   considered by the working group, and the working group has made an
   informed decision that the objection has been answered or is not
   enough of a technical problem to move forward, the chair can declare
   that there is rough consensus to move forward, the objection
   notwithstanding.  To reinforce that we do not vote, we have also
   adopted the tradition of "humming": When (for example) the chair of
   the working group wants to get a "sense of the room", instead of a
   show of hands, the chair asks for each side to hum for or against a

   However, in recent years we have seen participants (including folks
   in IETF leadership) who do not understand some of the subtleties of
   consensus-based decision making.  Participants ask, "Why are we
   bothering with this 'humming' thing?  Wouldn't a show of hands be
   easier?  That way we could really see how many people want one thing
   over another."  Chairs are faced with factious working groups with
   polarized viewpoints and long-running unresolved issues that return
   again and again to the agenda.  More and more frequently, people walk
   away from working groups, thinking that "consensus" has created a
   document with horrible compromises to satisfy everyone's pet peeve
   instead of doing "the right thing".  None of these things are
   indicators of a rough consensus process being used, and are likely
   due to some basic misperceptions.

   This document attempts to explain some features of rough consensus,
   explain what is not rough consensus, and suggest ways that we might
   achieve rough consensus and judge it in the IETF.

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      Note: This document contains the musings of an individual.  Right
      now, it is just some rough notes and has lots of holes that need
      to be filled in.  Even if those holes are filled, in its current
      form, it is not intended to be published as an RFC, let alone
      being a BCP for a change of IETF policy.  If it evolves into such
      a thing, great.  If it simply sparks discussion as an Internet
      Draft, that's a perfectly fine outcome.

2.  Lack of disagreement is more important than agreement

   A working group comes to a technical question of whether to use
   format A or format B for a particular data structure.  The chair
   notices that a number of experienced people think format A is a good
   choice.  The chair asks on the mailing, "Is everyone OK with format
   A?"  Inevitably, a number of people object to format A for one or
   another technical reason.  The chair then says, "It sounds like we
   don't have consensus to use format A. Is everyone OK with format B?"
   This time even more people object to format B, on different technical
   grounds.  The chair, not having agreement on either format A or
   format B, is left perplexed, thinking the working group has

   The problem that the chair got into in the above case was to think
   that what they were searching for was agreement.  "After all", thinks
   the chair, "consensus is a matter of getting everyone to agree, so
   asking whether everyone agrees is what the chair ought to do.  And if
   lots of people disagree, there's no consensus."  But _determining_
   consensus and _coming to_ consensus are different things than
   _having_ consensus.  Consensus is not when everyone is happy and
   agrees that the chosen solution is the best one.  Consensus is when
   everyone is satisfied enough with the chosen solution that they do
   not object to it.  The distinction might be a bit subtle, but it's
   important.  Engineering always involves a set of tradeoffs.  It is
   almost certain that any time engineering choices need to be made,
   there will be options that appeal to some people that are not
   appealing to some others.  The key is to separate those choices that
   are simply unappealing from those that are truly problematic.
   [[Example: insert catchy example here --PR]] So in the case of a
   working group decision, it is most important to ask not just for
   objections to a particular proposal, but for the nature of those
   objections.  A chair who asks, "Is everyone OK with choice A?" is
   going to get objections.  But a chair who asks, "Can anyone not live
   with choice A?" is only going to hear from folks who think that
   choice A is impossible to engineer given some constraints.  Then the
   purported failings of the choice can be examined by the working
   group.  The objector can convince the rest of the group that the
   objections are valid, or the working group might convince the

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   objector that the concerns can be addressed, or that the choice is
   simply unappealing (i.e., something the objector can "live with") and
   not a show-stopper.  In any event, closure is much more likely to be
   achieved quickly by asking for and trying to accomodate the
   objections rather than asking for agreement.

   This also brings up an important point about reaching consensus:
   Consensus does not really involve compromising.  "Compromising"
   implies that there remains something wrong with the outcome, but that
   the objector has simply given up.  To truly come to consensus does
   not involve making a compromise, but rather coming to the conclusion
   that either the objection is valid (and therefore changing the
   outcome), or concluding that the objection was not really a matter of
   importance, but merely a matter of taste.  Of course, coming to full
   consensus does not always happen.

3.  Rough consensus is when all issues are addressed, but not
    necessarily accommodated

   The preceding discussion gives an example where the working group
   comes to consensus on a point: Either the objector is satisfied, or
   the working group is satisfied.  But certainly that doesn't happen
   all of the time, and it's certainly not the problematic case.
   Engineering is always a set of tradeoffs.  Often, a working group
   will encounter an objection where everyone understands the issue,
   acknowledges that it is a real shortcoming in the proposed solution,
   but the vast majority of the working group believe that accommodating
   the objection is not worth the tradeoff of fixing the problem.  So,
   an objector might say, "The proposal to go with protocol X is much
   more complicated than going with protocol Y. Protocol Y is a much
   more elegant and clean solution, and protocol X is a hack."  The
   working group might consider this input, and someone might respond,
   "But we have a great deal of code already written that is similar to
   protocol X. While I agree that protocol Y is more elegant, the risks
   to interoperability with an untested solution is not worth it
   compared to the advantages of going with the well-understood protocol
   X." If the chair finds, in their technical judgement, that the issue
   has truly been considered, and that the vast majority of the working
   group has come to the conclusion that the tradeoff is worth making,
   even in the face of continued objection from the person(s) who raised
   the issue, the chair can declare that the group has come to rough

   Now, a conclusion of only rough consensus relies heavily on the good
   judgement of the consensus caller.  The group must truly consider and
   weigh an issue before the objection can be dismissed as being "in the
   rough".  The chair of the working group in one of these cases is

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   going to have to decide that not only has the working group taken the
   objection seriously, but that it has fully examined the ramifications
   of not making a change to accommodate it, and that the outcome does
   constitute a failure to meet the technical requirements of the work.
   In order to do this, the chair will need to have a good idea of the
   purpose and architecture of the work being done and use their own
   technical judgement to make sure that the solution meets those
   requirements.  What can't happen is that the chair bases their
   decision solely on hearing a large number of voices simply saying,
   "The objection isn't valid."  That would simply be to take a vote.  A
   valid justification needs to me made.

   Any finding of rough consensus needs at some level to be a
   satisfactory explanation to the person(s) raising the the issue of
   why their concern is not going to be dealt with.  A good outcome is
   for the objector to be satisfied that, although their issue is not
   being accommodated in the final product, they understand and accept
   the outcome.  Remember, if the objector feels that the issue is so
   essential that it must be attended to, they always have the option to
   file an appeal.  A technical error is always a valid basis for an
   appeal, and a chair or AD has the freedom and the responsibility to
   say, "The group did not take this technical issue into proper
   account."  Simply having a number of people agreeing to dismiss an
   objection is not enough.

4.  Humming is the start of a conversation, not the end

   More and more we see people who think that a hum is a sort of
   anonymous vote, with some chairs calling every question they have for
   the working group by asking for a hum and and judging the result by
   the loudest hum, even saying things like, "There were lots of hums
   for choice 1 and very few hums for choice 2, so it sounds like we
   have rough consensus for choice 1."  This really misses the point of
   humming and is probably mis-assessing the consensus.

   So, why do we hum?  The first reason is pragmatic.  Quite often, a
   chair is faced with a room full of people who seem to be
   diametrically opposed on some choice facing the group.  In order to
   find a starting place for the conversation, it is often useful for
   the chair to ask for a hum to see if one of the choices already has a
   stronger base of support than the other.  If choice "foo" has a
   significant amount more support than choice "bar", it is likely
   easier to start the discussion by saying, "OK, 'foo' seems to have
   quite a bit of support.  Let's have the people that think 'foo' is a
   bad idea come up and tell us why it is problematic."  At that point,
   the group can start going through the issues and see if any of them
   are showstoppers.  It may turn out that one of the objections is

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   instantly recognized by the entire group as a fatal flaw in "foo" and
   the group will then turn to a discussion of the merits (and demerits)
   of "bar" instead.  All that the hum does is give the chair a starting
   point: There were likely to be less objections to "foo" than to "bar"
   at the beginning of the discussion, so starting with whatever got the
   most hums can shorten the discussion.

   But couldn't the above could have been done with a show of hands
   instead of a hum?  Another reason we hum is because it actually gives
   the chair the opportunity to take the temperature of the room.  A
   smaller bunch of loud hums for choice A and a larger number of non-
   committal hums for choice B might indicate that some people believe
   that there are serious problems with choice B, albeit the more
   popular by sheer number of people.  The chair might decide that
   starting with choice A and getting objections to it is the easier
   path forward and more likely to result in consensus in the end.
   Remember, coming to consensus is a matter of eliminating
   disagreements, so the chair wants to choose the path that gets to the
   least objections fastest.  A bunch of people who are not strongly
   committed to B might have no real technical objection to A, even
   though it is not their first preference.  Taking the hum is to figure
   out how to start the conversation.  Unless, to the chair's surprise,
   the hum is unanimous, the hum begins the discussion; it doesn't end
   it.  And when a chair wants to get the temperature of the room, they
   should not leave the impression that the number of people count in
   any formal way; the hum makes it perfectly clear that the chair is
   simply figuring out the direction of the conversation.

   This also points to a misuse of the hum: If the chair is already
   convinced that the group has come to consensus, there is no reason to
   take a hum.  In fact, taking the hum only serves to discourage those
   who might be in the minority from voicing their concerns to the group
   in the face of a large majority who want to move forward.  The right
   thing for the chair to do if they already sense consensus is to say,
   "It sounds to me like we have consensus for choice A. Does anybody
   have any concerns or objections to going with A?"  This allows folks
   to bring up issues to the group that the chair might have mistakenly
   missed without having them feel that the majority has "already

   There are times where the result of a hum is a pretty even split.  In
   practical terms, that means it doesn't matter where the chair starts
   the discussion.  And in fact, we've had working groups where a coin-
   flip decided which proposal to start with.  That doesn't mean that
   the coin-flip determined the outcome; if a fatal technical flaw was
   found in the chosen solution, it is still incumbent upon the group to
   address the issue raised.  Rough consensus on the technical points,
   in the end, is always required.  Any way to find a place to start, be

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   it the hum or the coin-flip, is only getting to the beginning of the
   discussion, not the end.

5.  One Hundred people for and five people against might not be rough

   Remember that consensus is found when all of the objections have been
   addressed.  This is how using rough consensus avoids the pitfall of a
   straight vote: If there is a minority of folks who have a valid
   technical objection, that objection must be dealt with before
   consensus can be declared.  So in a large working group with over 100
   active participants and broad agreement to go forward with a
   particular protocol, if a few participants say, "This protocol is
   going to cause congestion on the network, and it has no mechanism to
   back off when congestion occurs; we object to going forward without
   such a mechanism in place", and the objection is met with silence on
   the mailing list, there is no consensus.  Even if the working group
   chair makes a working group last call on the document, and 100 people
   actively reply and say, "This document is ready to go forward", if
   the open issue hasn't been addressed, there's still no consensus.
   It's the existence of the unaddressed open issue, not the number of
   people, which is determinative in judging consensus.  As discussed
   earlier, you can have rough consensus with issues that have been
   purposely dismissed, but not ones that have been ignored.

6.  Five people for and one hundred people against might still be rough

   This one is the real mind bender for most people, and certainly the
   most controversial.  Say there is a very small working group, one
   with half a dozen truly active participants who are experts in the
   field; everybody else is just following along, but not contributing
   to the discussion.  The active folks come up with a protocol document
   that they all agree is the right way forward, and people inside and
   outside the working group agree that the protocol is likely to get
   widespread adoption; it is a good solution to a real problem, even if
   the non-experts don't have the ability to fully judge the details.

   However, one of the active members has an objection to a particular
   section: The protocol currently uses a well-known algorithm to
   address an issue, but the objector has a very elegant algorithm to
   address the issue, one which works especially well on their
   particular piece of hardware.  There is some discussion, and all of
   the other contributors say, "Yes, that is elegant, but what we're
   using now is well-understood, widely-implemented, and it works
   perfectly acceptably, even on the objectors hardware.  There is

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   always some inherent risk to go with a new, albeit more elegant,
   algorithm.  We should stick to the one we've got."  The chair follows
   the conversation and says, "It sounds like the issue has been
   addressed and there's consensus to stick with the current solution."
   The objector is not satisfied, maybe even saying, "But this is silly.
   You've seen that my algorithm works.  We should go with that."  The
   chair makes the judgement that the consensus is rough, in that there
   is still an objector, but the issue has been addressed and the risk
   argument has won the day.  The chair makes a working group last call.

   Now the worst case scenario happens.  The objector, still unhappy
   that their preferred solution was not chosen, recruits one hundred
   people, maybe a few who were silent participants in the working group
   already, but mostly people who are at the same company as the
   objector who never participated before.  The objector gets them all
   to post a message to the list saying, "I believe we should go with
   the new elegant algorithm in section 5.6 instead of the current one.
   It is more elegant, and works better on our hardware."  The chair
   sees these dozens of messages coming in and posts a query to each of
   them: "We discussed this on the list, and we seemed to have consensus
   that, given the inherent risk of a new algorithm, and the widespread
   deployment of this current one, it's better to stick with the current
   one.  Do you have further information that indicates something
   different?"  And in reply the chair gets utter silence.  These
   posters to the list (say some of whom were from the company sales and
   marketing department) thought that they were simply voting and have
   no answer to give.  At that point, it is within bounds for the chair
   to say, "We have objections, but the objections have been
   sufficiently answered, and the objectors seem uninterested in
   participating in the discussion.  Albeit rough in the extreme, there
   is rough consensus to go with the current solution."

   There is no doubt that this is the degenerate case and a clear
   indication of something pathological.  But this is precisely what
   rough consensus is designed to guard against: vote stuffing.  In the
   presence of an objection, the chair can use their technical judgement
   to decide that the the objection has been answered by the group and
   that rough consensus overrides the objection.  Now, the case
   described here is probably the hardest call for the chair to make
   (how many of us are willing to make the call that the vast majority
   of people in the room are simply stonewalling, not trying to come to
   consensus?), and if appealed it would be incredibly difficult for the
   appeals body to sort it out.  Indeed, it is likely that if a working
   group got this dysfunctional, it would put the whole concept of
   coming to rough consensus at risk.  But still, the correct outcome in
   this case is to look at the very weak signal against the huge
   background noise in order to find the rough consensus.

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7.  Security Considerations

   "He who defends with love will be secure." -- Lao Tzu

8.  Informative References

   [Clark]    Clark, D., "A Cloudy Crystal Ball - Visions of the
              Future", July 1992.

              In "Proceedings of the Twenty-Fourth Internet Engineering
              Task Force" [IETF24], July 13-17, 2004, pages 539-543.

   [IETF24]   Davies, M., Ed., Clark, C., Ed., and D. Legare, Ed.,
              "Proceedings of the Twenty-Fourth Internet Engineering
              Task Force", July 1992,

   [Sheeran]  Sheeran, M., "Beyond Majority Rule: Voteless Decisions in
              the Religious Society of Friends", December 1983.

Appendix A.  Acknowledgements

   This document is the result of conversations with many IETF
   participants, too many to name individually.  I greatly appreciate
   all of the discussions and guidance.  I do want to extend special
   thanks to Peter Saint-Andre, who sat me down and pushed me to start
   writing, and to Melinda Shore for pointing me to Beyond Majority Rule
   [Sheeran], which inspired some of the thinking in this document.

Author's Address

   Pete Resnick
   Qualcomm Technologies, Inc.
   5775 Morehouse Drive
   San Diego, CA  92121

   Phone: +1 858 6511 4478

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