Why the 10th Man Rule is relevant

World War Z is an amazing zombies book with a terrible and unique movie adaptation. As far as I know, it is the only zombies film not featuring a single drop of blood or seen zombie bite, I guess because they spent all the budget on both Brad Pitt's salary and the marketing campaign. But there are learnings even in bad things, and this scenario is no less. In one scene, a character describes the 10th Man Rule (also known as devil’s advocate), which proposes:

Produce a range of explanations and assessments of events that avoid relying on a single concept [...].
If ten people are in a room, and nine agree on how to interpret and respond to a situation, the tenth man must disagree. His duty is to find the best possible argument for why the decision of the group is flawed.

Now, this rule can be real or can be fictional, but anyway I like it and sometimes apply it. Usually in the context of everyone saying the pros and I focusing on the cons, but the opposite can also happen.

I think this rule is relevant in discussions because in a perfect world we would gather different experts and stakeholders and spend as much as needed thinking and talking about approaches, choices and trade-offs about any proposal or technical requirements specification, but the reality usually goes more along the lines of:

• If the proposal comes from Product, usually speaks little of trade-offs and difficulties (other than listing existing ones as justification for the proposal itself)
• If the proposal or tech spec comes from Engineering, my general feeling is that, with all this "perversion of agile" we can now mostly say "I wanna do X" and just jump into building it, losing that phase of properly researching or simply giving some thoughts to how to achieve your goal; what I sometimes call "think before you code". I am not a fan of endless documentation, but writing a tech spec forces you to think about your action plan at least once [1].

Circling back to the main point, we can say we usually attend a meeting or review a proposal which many times lacks depth. Now, ignorance is bliss they say, and sometimes that is good because if you don't know you can't do X because it's impossible, you might find a way to actually do it [2]. But often those meetings are either echo chamber or an environment where there's some aversion to voice concerns (to "say no"). I'm pretty sure everyone has at least once been in a situation of being faced with everyone else thinking "A is best" while we think "Are you all blind? B is clearly best!".

The purpose of this rule is not be an excuse to become the grumpy person who always points out the flaws, but to enable discussions that challenge the main approach and avoid group thinking (which usually impedes individual thinking). Note that this does not mean you can be disrespectful or impolite, of course.

It is nice to do positive thinking and generally seek a "how yes", but we must not forget to also think about the "why not" at some point.

[1]: I view it the same as explaining a subject to somebody else helps you study it. Forcing to explain or detail something enforces retaining what you learn.

[2]: Wasn't some quote along the lines of "Nobody told me it was impossible, so I did it"?