Electrical engineer and computer scientist Lotfi A. Zadeh is a professor emeritus at the University of California (UC), Berkeley, and director of the Berkeley Initiative in Soft Computing. In January, Zadeh received the latest of a long string of awards when the Spanish BBVA Foundation recognized him with the 2012 BBVA Foundation Frontiers of Knowledge Award, in its Information and Communication Technologies category, "For the invention and development of Fuzzy Sets and Fuzzy logic, a revolutionary concept and methodology that created a new field of research, which proved powerful in many application domains."

In 1965, Zadeh challenged scientific dogma by introducing fuzzy set theory, in which variables can have a truth value anywhere between 0 and 1, rather than only 0 or 1 as in classical logic. "This paradigm very significantly contributed to the progress of reasoning with imprecise concepts and provided a new approach to qualitatively represent human knowledge," the prize jury wrote.

Zadeh developed fuzzy logic further to deal with complex systems and decision-making processes and nowadays, several thousand researchers around the world work in the field. Numerous real-life applications including video cameras, blood pressure meters, wastewater treatment plants, and the subway system in Sendai, Japan, also depend on Zadeh's insight. Yet the controversy surrounding fuzzy logic has not entirely dissipated.

Science Careers talked to Zadeh to find out what it is like to advocate a controversial idea, and about the resulting career risks. These interview highlights have been edited for brevity and clarity.

Q: How did the idea for fuzzy logic come to you?

L.A.Z.: I have been concerned with systems analysis for many, many years and I began to realize at some point that traditional approaches do not work that well with human-centered systems. They work well in the case of physical systems, but they don't work that well in the social realm, in politics, in medicine, and so forth. A simple idea occurred to me. In the world of mathematics, for example, everything has sharp boundaries, either it's a circle or it's not a circle, either the lines are parallel or not parallel. But in the real world, when it comes to, "is this person honest, or tall, or beautiful?" the boundaries are fuzzy.

Q: At the time, how well established were you in your career?

L.A.Z.: That was 1964. I was 43 years old and reasonably well known for my contributions to systems analysis. I was chair of the department here at UC Berkeley, so I was busy with administrative problems. Nevertheless, once the idea occurred to me I was able to develop it very quickly.

Q: How controversial was the idea back then?

L.A.Z.: The idea was controversial right from the very beginning, in part because I used the word fuzzy, which is usually not used in scientific literature. But another reason is that it went away from the Cartesian mentality, where everything is black and white. If I were a junior person, I couldn't get away with that idea, but because I was a senior person and chair of the department, people listened to me. Some would agree and some would disagree.

Q: How harsh did the criticism get?

L.A.Z.: I could give an hour's lecture citing the nasty things that people said, but just to give you an example, which occurred later, I was giving a lecture in France, and a well-known person said, "You know that what professor Zadeh told you is complete nonsense and if he gives that kind of a talk in the United States, he would be lynched."

Q: Was this hard to take?

L.A.Z.: For me it was not hard to take. I have a very thick skin. I think that I was born with it, but with the passage of time my skin became thicker. A piece of advice that I give to people is, if somebody tells you that you're an idiot, respond by saying, "I'll take it as a compliment."

Furthermore, I'm the kind of person who has confidence in his judgment. I was sure that I was right, and so when people around me were telling me that I was wrong, that did not influence me.

Q: Did you ever feel discriminated against?

L.A.Z.: Yes, sometimes I felt discriminated against openly, but sometimes it was behind my back. You may submit a proposal and they will not tell you that it's turned down because it's useless fuzzy logic, they will come up with some other excuse. And that is particularly true in the case of awards. Somebody nominates you for an award, and then somebody on the committee will blackball you and say, ''No, I heard that this is no good.'' Once even a single member expresses that kind of an opinion, the chances are that you will not get the award.

Q: Did your idea also receive encouragement?

L.A.Z.: Richard Bellman was a brilliant mathematician and he extended strong support to me in writing and in other ways. But my stronger support came from Japan. My paper was published in '65. In '66, I received some letters from Japan, from members of the Electrotechnical Laboratory in Tokyo, saying that they saw my paper and they thought that it could be useful in dealing with pattern recognition. And in 1968 many papers dealing with fuzzy sets began to appear in Japanese journals, so early on reaction in Japan was very positive.

Q: How important was this positive feedback to you?

L.A.Z.: As I said, I have a thick skin, but it was important for me to see that there were some people who understand the potential of the idea. I could recognize right from the beginning that this was going to be an important thing.

Q: Did you ever doubt your research and its relevance?

L.A.Z.: No, I never had any doubts. At the time I came up with that idea I was not a neophyte, so I had a pretty good understanding of what's important and what's not important back then.

Q: Would you have been able to pursue your idea if you had been younger?

L.A.Z.: In some sense I was fortunate that the idea occurred to me when I was in an established position so people would listen to what I had to say. A young scientist would have a much harder time. Also, when I had to decide which journal to submit my first paper to, I knew that if I submitted to a journal for which I had no connection then there was a high probability it would be rejected. I sent it to Information and Control. The reviews that I received were very lukewarm, but because I was a member of the editorial board, my paper was published as a matter of courtesy.

Q: Do you think that it is even more difficult for young scientists nowadays to take risks?

L.A.Z.: Today, young scientists have become somewhat cynical. They know that what matters is money. If they don't succeed in getting funded, they would be in trouble. Personally, I find that to be very disconcerting. That's not the way things were when I was beginning my career.

Q: How should young scientists with a revolutionary idea proceed?

L.A.Z.: It depends. My idea was controversial, and there are other ideas, particularly in the realm of information systems today, which are revolutionary. But they are not controversial, so they are accepted right away.

Q: What if the idea is controversial?

L.A.Z.: Well, it's difficult. When one is an assistant professor or being considered for a junior position and then you open your mouth and you say something that's controversial, then you may pay a price for it. So I would not advise a person to be very vocal about it. You have to do it diplomatically, quietly. There was a time when, if you wrote a thesis with 'fuzzy' in the title, it would be difficult for you to get a job. So at that point I would advise people who were writing their thesis not to use 'fuzzy' in their title. My advice was not to fight, but to accept that there are certain prejudices, and one has to adjust himself or herself to the reality of these prejudices.

Q: Would you recommend that they just wait until they have a permanent position?

L.A.Z.: If there is a risk of retribution, punishment, or discrimination, yes, I would do so. I would not suggest that a person act like David challenging Goliath, because you get beaten on the head, and you may pay a heavy price. I know some young, good people who paid the price; I mean, they were not appointed, they were not promoted, all kinds of things happened to them.  

Q: Do you have any final advice you would like to pass on to young scientists?

L.A.Z.: There are two things that are very important. The most important one is not to be discouraged. If your paper gets turned down, don't be discouraged. If a proposal gets turned down, don't be discouraged. If you cannot get a job, don't be discouraged. I know many, many people who have become well known and successful because they were persistent above anything else. I am the kind of person who is persistent, and to a considerable extent this has helped me.

But at the same time, luck is an important element. There are some people who have potential for becoming great scientists, but they don't become great scientists. Something happened in their life that diverted them. This is like healthy living to the extent that you can try to live a healthy life, but at the same time be aware of the fact that life can be cruel and things can happen that are unforeseen and beyond your control.

But again, more important than anything else is being persistent. No success? Try to work harder.

Elisabeth Pain is contributing editor for Europe.

10.1126/science.caredit.a1300115