Few will dispute the fact that this world we live in is built on ideas. They encompass anything between the ideals of democracy to the relatively more recent technological conveniences such as the Internet.

But there are also bad ideas, ranging from those that inform the demented pseudo-Islamic ideology driving Al Shabaab, genocide ideology or the xenophobic mania that, underwritten by real or imagined economic grievances, has recently been overrunning South Africa against their fellow Africans.

There’s no question such ideas must be banished from human experience. This is obvious. Yet there are others that, though good, may have outlived their usefulness.

Some of these have been discussed in a new book titled, "This Idea Must Die: Scientific Theories That Are Blocking Progress.” This is the latest in a series of annual books posing a question every year to some of the best minds.

The brainchild of John Brockman, the founder of the intellectually stimulating edge.com, the current book is a compendium of answers to the question, ”What scientific idea is ready for retirement?” posed to 175 of the world’s greatest scientists, philosophers, and writers.

As Brockman explains it, few truly new ideas are developed without abandoning old ones first. And, as theoretical physicist Max Planck (1858–1947) noted, "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”

It will also be recalled that it was Victor Hugo, the great 19^th Century French writer and poet, who memorably once said that there is no force in the world so powerful as the idea whose time has come.

That may be true. But the world is a bit more complicated, as the complexity of how brilliant ideas (even demented ones) rise they mesh into each other and grow, building upon the other to their logical fruition before they simply dissipate or die.

The scientists, philosophers and writers in Brockman’s book point to a plethora of "retirement-ready” ideas that, among many others, include IQ, the self, human nature, free will, and even love.

Let’s sample a couple of them, say, free will and love.

According to some of the arguments, consciousness is an illusion constructed by a clever brain and body in a complex social world. We can speak, think, refer to ourselves as agents or decision maker, but it is a false idea of a persisting self that has consciousness and free will.

"Although we can experience the mental anguish of making a decision… the choices and decisions we make are based on situations that impose on us. We don’t have the free will to choose the experiences that have shaped our decisions.”

This echoes the classic philosophical assertion referred to as determinism that there is a cause for every event, including human action.

Love has been described as "positive addiction” and needs to be rethought.

Biological anthropologist Helen Fisher, who studies the brain on love, writes: "Besotted lovers express all four of the basic traits of addiction: craving, tolerance, withdrawal, and relapse. They feel a "rush” of exhilaration when they’re with their beloved (intoxication)...If the love object breaks off the relationship, the lover experiences signs of drug withdrawal, including protest, crying spells, lethargy, anxiety, insomnia (lack of sleep), loss of appetite […], irritability, and loneliness. Lovers, like addicts, also often go to extremes, sometimes doing degrading or physically dangerous things to win back the beloved. And lovers relapse the way drug addicts do. Long after the relationship is over, events, people, places, songs… associated with their abandoning sweetheart can trigger memories and renewed craving.”

While I do not claim to have captured the complexity of the arguments, it is beyond this column to delve so deep; except to merely point out that if the idea of love and self can be singled out for "retirement”, what about the odiously foul ones as those that stoke Al Shabaab’s madness and genocide ideology?

By relentlessly questioning the sanity of negative ideas in minds they might be sowed, they too must go. It’s just a matter of time.