It may go against current ideas, but I believe the trend for demanding evidence too often goes too far.
To be clear, one major, positive change in recent years has been the ability and expectation to make product decisions based on real user data. Once upon a time these decisions were made by the HIPPO (highest paid person’s opinion), but now it’s possible to do much better than that, doing small experiments and reacting accordingly. This has given rise to the culture of the lean startup, among other things, and it’s now considered an achievable ideal. It happens at the lower levels of detail, too—it is more common today to make estimates based on the evidence of the previous few days or weeks, and judge accordingly. There used to be much more “estimation” based on wishful thinking. In both cases we still have a long way to go, but I’d say the trend is in the right direction.
But this can go too far. I’ve seen too many Twitter exchanges, or been involved in personal exchanges, where one party asks the other “do you have evidence for that?” Usually this is after the first person has expressed a view or an opinion. The effect here is different—it’s not about trying to make the best decision. In these circumstances it’s difficult to imagine what “evidence” might entail, and the reaction could too easily be “You know I don’t have a controlled experiment to back that up; you’re just trying to close me down”. That’s certainly how I usually read it.
Evidence-based decision-making is about making well-informed choices for potentially costly decisions. But elsewhere the best way to make informed choices is to keep options open and invite opinions.
Used too early the “what is your evidence?” question can be confrontational and create opposition. It’s a shame, because it’s a powerful weapon at the right time, and deployment too early can reduce that power by setting people against it in advance.
By the way, in thinking about this article I started drawing a parallel with non-violent communication (NVC), which attempts to remove confrontation from communication. However the Wikipedia page on the subject says “Some researchers have noted that NVC lacks an evidence base…” So if you’re going to ask if I have evidence for all this, you know what the answer is.