(Today my graduate research class begins; here is advice for new researchers.)
"Son, don’t marry for money; hang around rich girls and marry for love." A joke I heard years ago from Chip Morningstar.
Research topics work similarly. Don’t research a topic because it is popular; expose yourself to many popular topics and you will fall in love with a few. Fall in love with a dozen topics; too few and you’ll linger too long after they fail. Consider:
Fred, Ned, and Ted had never left their home town, but wanted careers as explorers. They heard others had explored hills and caves nearby, but that seemed boring; they read of famous explorers going more interesting places. So Fred, Ned, and Ted got out a map and chose their first places to explore: the deepest ocean, the longest cave, and the moon. They were never heard from again.
To learn to explore, first follow the paths of previous explorers, first on a map, then from the air, then down on the ground. Next, try going a mile off of one of those paths. Then ten miles, then one hundred. Similarly the best way to start researching is to take a good research paper and really understand it. Then make a minor change, such as an assumption or data analysis technique. Then make bigger changes.
Another problem with passion is bias. Especially in social science, people pick topics in order to convince the world of their one true answer. But it is healthier to focus on questions, not answers. By picking an answer before you’ve really studied a topic, not only are you more likely to be wrong, but more important, you could miss interesting new angles.
My colleague Bryan Caplan is the sharpest thinker I’ve personally known. He has a penetrating insight and willingness to embrace uncomfortable conclusions, except on a few topics, such as free will, dualism, and libertarian ethics, where he developed strong intuitions early. Fortunately for Bryan, while these opinions may motivate his research, he had not directly worked in those areas. Similarly, I have to admit it was good that I spent most of research time away from the topics I was the most passionate about.