Table of Contents

Origin: Ray Dalio's Principles. Summarised here: On Lying To Yourself.

Technique Goal: An efficient heuristic for evaluating who to ask feedback from. Also worth using during decision-making: i.e. 'believability weighted opinions'. The example here being a) you need to make a decision, b) you approach a variety of people to get advice, c) you incorporate their views and weight their advice according to their believability.

Technique summary:
Believable people are people who have 1) a record of at least three relevant successes and 2) have great explanations of their approach when probed.

You may evaluate a person's believability on the subject matter at hand by applying this heuristic. When interacting with them:

  1. If you’re talking to a more believable person, suppress your instinct to debate and instead ask questions to understand their approach. This is far more effective in getting to the truth than wasting time debating.
  2. You’re only allowed to debate someone who has roughly equal believability compared to you.
  3. If you’re dealing with someone with lower believability, spend the minimum amount of time to see if they have objections that you’d not considered before. Otherwise, don’t spend that much time on them.

Technique context: Ray Dalio developed this technique while running Bridgewater. Bridgewater is one of the world's most successful hedge fund (at least circa 2018). In his book, Principles, he mentions using it when seeking a diagnosis for a health problem, as an example of its applicability outside a work environment.

Possible Preconditions: You are able to detect people's believability accurately. For instance, a successful venture capitalist giving you operational advice for your company — is the venture capitalist high believability? This depends: if they have never successfully built a company, you might want to discount this advice. Conversely, if the same venture capitalist is telling you about the broader startup investment market, he has higher believability due to his work and you should listen carefully.

Counter-test (how to know if this works for you): If this causes you to miss out on some good advice, you might want to revisit your implementation.

Notes: I've put this into practice for a bit now. The key here is that you should beware rejecting advice from lower-believability people simply because they are lower-believability. Spend the minimum amount of time to check their objections, just to make sure you're not missing something basic and true.

With that said, this can be fixed fairly easily by seeking out and talking to more high believability people.

Related: The Hierarchy of Practical Evidence, and for notes on application: Believability in Practice.