blog.pmarca.com: How to hire the best people you've ever worked with:

One way to test for an aspect of ethics -- honesty -- is to test for how someone reacts when they don't know something.

Pick a topic you know intimately and ask the candidate increasingly esoteric questions until they don't know the answer.

They'll either say they don't know, or they'll try to bullshit you.

Guess what. If they bullshit you during the hiring process, they'll bullshit you once they're onboard.

A candidate who is confident in his own capabilities and ethical -- the kind you want -- will say "I don't know" because they know that the rest of the interview will demonstrate their knowledge, and they know that you won't react well to being bullshitted -- because they wouldn't react well eithe

This has always been a paramount issue for me when assessing others. Be willing to say, "I don't know." It's my experience that a person who will say "I don't know" can be counted on not to mess things up. And in the systems world, that is an important thing. I've never worked with anyone who knew everything, though I have worked with some people who sure seemed to know a whole lot. I have, however, also worked with people who thought they knew everything. Those were the people you kept from the root password.

They're not only at work. I see them in law school, too. They blather on about topic after topic, often very incorrectly. I don't know everything about the law or law school, but I do know some things, and I know when these folks are wrong.

During the Intensive Advocacy Program, we were instructed on using not knowing things to our advantage. In the alternative, since you're seldom supposed to find yourself unprepared in court, we were instructed to make it seem like we didn't understand some of the testimony going on. We needed to put ourselves in the shoes of the jurors and bring out the necessary testimony. During IAP, watching jury deliberations, we also got to see the know-it-all thing happening. In the criminal trial I observed, two jurors ran away with the deliberations, putting their feet down, spouting all sorts of "facts" about the gun, trigger pull, physical responses to gunshots, etc.

When I was in Air Force ROTC field training, we had six responses* we could use when addressed. "Yes, sir" and "No, sir" were the most common. The handiest was "Sir, I do not know, but I will find out." In the very worst case, you were then criticized for not knowing something. On the flip side, you took responsibility for that failure and promised to follow-up. Of course, it was critical to follow-up.

What was the alternative? "No excuse, sir." That was never acceptable. That was put in place as a trap. Obviously, the statements aren't congruent, but "No excuse, sir" often followed a weasely attempt at quibbling, another big no-no. Such quibbling was easy short-circuited by owning up to the deficiency in the first place.

The same holds for those interviewing or those you work with. If you don't know, just tell me you don't know.

* The six responses were: Yes, sir; No, sir; Sir, may I make a statement; Sir, may I ask a question; Sir, I do not know, but I will find out; and No excuse, Sir. That's just how ingrained in us they were; fifteen years later, I still know them.