Credibility is one of the most fundamental aspects of how we deal with people. It may not have anything to do with how much we like a person, or how much we trust them with other aspects of friendship. Someone’s credibility is concerned with how much stock you can place in someone’s statements.In science, I deal with this all of the time. Just because someone has a degree does not make them credible.Indeed, there are plenty of people with a degree in a field who are not a reliable source of information about that particular field, much less other aspects of life. Case in point: you can find an MD to endorse anything.

So – how do you evaluate someone’s credibility? A degree is not a bad place to start, I’ll admit.If someone has gone to the trouble to jump through hoops about some subject and invest some money, they probably have enough interest to stay informed.But that’s inductive reasoning, at best. What else is there? There’s how they dress. Believe it or not, that’s a big factor in many circles (consciously or otherwise).There are any number of other, external factors that might go into an initial evaluation of a person’s credibility.If you want an interesting book on some of the intangible, unconscious ways we make these judgments, have a look at Malcolm Gladwell’s Blink.

I suppose that in an ideal world, we would evaluate people’s ideas on their own merits.That is to say, if you want to know if a physicist’s ideas about high energy particle trajectories are correct, you learn high energy particle physics and work through his math.That’s probably not practical in most cases, and is likely impossible for most people.When it comes to complex intangibles (like particle physics and investments) people will gravitate to a source of authority and just trust that expert’s opinion.For that authority figure, I suggest that it makes sense to find someone who servers your interest.

So if you are looking for someone who serves your interest, how can you tell?It’s not unreasonable to concern yourself with how he dresses or how well his office is decorated.Did he take the time to consider your comfort?That’s one aspect of being polite.If you have the wherewithal to get into some of the technical nitty-gritty, it’s wise to check his opinions about big-picture subjects and see if he can state them clearly.Does he disagree with any of the big thinkers of the day?That may not be a bad thing, but he had better be able to explain where he departs from the status quo and why.Can his position be attacked by reductio ad absurdum?

But in the end, one of the biggest deciding factors is this: Follow the money.If you are considering taking someone’s advice, ask who is paying this person to advise you. The big upshot: ask yourself (1.) who made his suit and (2.) who paid for it.

-Peter