One of the most intense moments in the life of Antanas Mockus was when he came face to face with an aggressive-looking man who grabbed him and with emotion said: "You can make the good side stronger in me and get a good man out of me."

That desire of his fellow Colombians to improve has been at the heart of the career of this professor-turned-politician, known during his two terms as mayor of Bogota for his surprising and often humorous initiatives. Mockus said that while Colombians tend to think negatively about their neighbours, they usually discover that people have the capacity to be better than they think.

Mockus, who presided over Bogota first in the 1990s and again from 2001, has focused on human behaviour throughout his political career, conducting a series of social experiments to improve the city's services. He once hired 420 mime artists to make fun of traffic violators because he believes Colombians fear ridicule more than being fined.

This philosophical approach to leadership helped Mockus transform the city in his first term, cutting the homicide rate by an impressive 70% and traffic fatalities by more than 50%.

His background helped him earn public trust. While 6% of people trust politicians, 60% trust professors, according to Mockus, who is a blend of the two. He started his career as a professor of mathematics and philosophy at the National University of Colombia before he was forced to step down after mooning a disruptive group of students in an auditorium.

As mayor, Mockus took what was seen as a radical approach in raising taxes. "The first time I ran for mayor, people thought I was joking when I suggested raising taxes. They couldn't believe a candidate proposing more tax, but at the local level it worked," he explained. The city also introduced a "plus value tax" to pay for any public work done in an area. "So if you want a new road people pay for it locally," he explained. "Your home will increase in value if there is a better road, so you are investing in the area."

Mockus believes that being a mayor does mean conforming to some traditional criteria, but other things are important, including being creative and innovative, and playing the role of a "hero". Mockus's interpretation of this in his first term as mayor was dressing as a "supercitizen" in spandex to urge people to take care of their environment.

Mockus acknowledges that both Bogota and Colombia still have problems, one of which is that many young, middle-class people from the country are going abroad, to countries such as Australia and Canada But as yet, an ageing population is less of a concern in Colombia than in the UK, because older people tend to live with their families.

In 1998, between his two terms as mayor, Mockus made an unsuccessful bid for his country's presidency, mainly because he wanted to take his social experiment onto a national stage, to combat what he describes as the "horrible disorder" he saw in the rest of the country.

But the qualities that helped him succeed as mayor may not have helped his presidential candidacy, including a certain level of modesty. Unlike other politicians, Mockus says that his slogan has always been to "build on what has been built" and he said that one of the stupidest things in politics is "saying that you are the best."

He added: "Sometimes you have to speak in the future perfect tense, knowing you will not win."

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