"Invest in What You Know"? Maybe, Maybe Not.

Recently, health-care bureau chief Max Macaluso sat down with Motley Fool co-founder David Gardner to talk about the fear that some investors face when analyzing stocks in complex industries such as biotech and pharmaceuticals.

In this video segment, David describes Peter Lynch's advice to "invest in what you know" as a great starting point, but he doesn't think investors need to be limited to their own areas of expertise. He explains how, without any scientific knowledge of his own, he picked Amgen (AMGN 1.11%) as his first biotech investment several years ago. The full version of the interview can be seen here.

A full transcript follows the video.

Max Macaluso: When you look at Peter Lynch saying, "Invest in what you know," you don't necessarily agree or disagree with that statement.

David Gardner: Yeah, I would say that it's a great starting point.

Let me digress briefly, because that's the nature of this conversation. We started to do radio 15 or so years ago. Tom and I were hosting a coast-to-coast, national, three-hour, Saturday, live AM radio show in the top stations in a lot of the cities across America. I got great advice early on about doing radio, because I -- undergrad at North Carolina -- I didn't even show up at the local radio station. I had no experience as a DJ or anything else.

The advice that I remember that I got from -- I think it was somebody who was interviewing at our company at the time. I'm not even sure we hired him, but it was great advice in that job interview. He said, "A lot of people say, 'How do you do radio better?'"

How do you do videos better, Max?

The answer is not, "Try to do videos better," or "Try to be a radio guy." The answer is, "Lead a more interesting life," and then just talk about it. I always loved that answer, for broadcasting. If you have the privilege of being in front of a camera, it's not so much about trying to be really good on camera. It's actually doing interesting things, because then you have stuff to talk about.

Pulling that right back into our conversation now, I would say that it's not about "Invest in what you know" if what you know ... well, it is about "Invest in what you know." But you need to grow what you know.

Max: Right. "Invest in what you're interested in," I guess.

David: Sure.

Max: And be interested in everything.

David: That's my approach. That's my approach. The good news is, it's a rapidly expanding tech world, and if you can embrace and awaken your mind to that, I think you'll see stuff that other people don't. The bad news -- because in every strength there's a weakness -- the bad news is that you end up being a mild wide and an inch deep.

Max: Right.

David: That's kind of what I am.

Max: Actually, if you think back to the first biotech stock that you invested in, without any scientific training, how did you go about learning about the company and trying to understand what they were developing?

David: That's a great question. I think the first biotech stock I bought was Amgen (AMGN 1.11%). That was, like every stock I've picked, right out front of our Motley Fool members. It was back in the late '90s, when our portfolio was free on the site. Anybody could come and see the real money we were investing, and Amgen I picked.

How did I pick that, or why did I feel good about that?

It was a large-cap stock. I think if you're getting your toes wet, shallow end are big companies, big stocks. Dipping your toe with Amgen is a lot easier than dipping your toe with a company that has a $150 million market cap, and has never shown a profit to date, and whose burn rate will have it out of money in 18 months.

Max: Right, and it has a risky binary event coming up.

David: Absolutely.

That's what a lot of people think when they think about biotech investing. I think they have that caricature in their heads. But you know, and a lot of our Motley Fool followers and members know, that it's a rich industry. You can find massive companies -- the IBM of biotech, which is kind of an Amgen-like company -- right down to rinky-dink "bet it all on red" kinds of opportunities. I think too many people think it's the latter, and not enough the former.

At least for my first biotech, my launching point was with an awesome company -- and by the way, it looked expensive at the time. It already looked like it had moved, and it went on over the next 10 years, I think, to triple again, which so often the great companies do.

Max: Right, and now it's paying you dividends, maturing, but it's still disrupting certain industries within health care.

David: Yeah. It's an amazing company. And by the way, we closed that portfolio down in 2002 as we transitioned our whole business model into a subscription-oriented business, so I haven't kept up with Amgen in particular. I don't even know how it's done the last five years or so.

A lot of our picks in Stock Advisor and Rule Breakers are some smaller and mid-cap biotechs as well -- and that's just biotech -- I know we can talk health care, etc. It's a great big world out there.