Topic: Never act (blindly) on recommendations. always do the math yourself, always make sure you understand the level of certainty of the premises and facts, the solidity of the logic, and the probability of the conclusion.
Discussion: A recommendation, be it regarding an investment or a life altering decision, should only be a starting point and inspiration for your own investigation; and preferably one of several such inputs
Rule of thumb: trust no one
As an investor and portfolio manager I received as many recommendations a day I had time to listen to. They proved “right” within a reasonable time horizon about half of the time, i.e., as recommendations per se they were useless. No matter, I still got tremendous value from my analyst meetings.
I never cared about the recommendations as such; I only listened to the facts that had been painstakingly collected and documented. If anything, I made it a point to pay extra attention to the points brought forward by analysts with a different conclusion than mine. I then constructed a bigger picture of all the various data sources I had access to, some conflicting, some supporting. Not least, I gauged what the weighted average of important analysts views were.
Owing to my particular vantage point as a billion dollar hedge fund manager with access to all the largest Wall Street firms, I thus had an informed view of both all the facts, and what all other players thought were the facts and what their recommendations were. Consequently, I could slightly more reliably than most other investors take outperforming positions. Despite my privileged and advantageous position, I still had to build my own models, draw my own conclusions from a wide array of data, and not least make assessments of the relevance and reliability of the information I received.
“Try pouring a ton of steel without rigid principles”
You wouldn’t put your hand through molten metal without understanding the principles, would you? Or pouring a ton of steel without all the facts. So, why would you invest your own or clients’ money without understanding the risks, the facts and the logic involved?
Investing is hard. Anybody who claims it’s not is either stupid or selling something. If it seems to good to be true, it is, so make sure you know what the relevant facts are, and how they interact causally for the required conclusion.
Please note that this principle is valid in all aspects of life and decision making — trust no one to make your decisions for you.