We're all the children of amateurs: amateur parents. There's no government department that will certify you as a parent (thankfully), nor a university department where you get your PhD in being a daddy, nor a professional body ready to strike you off for not following mothering standards. But any parent who's held a newborn child in their arms has unconsciously taken the amateur's oath: "I may not be a professional, but I'm going to do whatever it takes to act like one."

It's a pity that too often we associate amateur with amateurish, and dismiss amateurs as second-rate pretenders to a professional throne. What we should remember is that the word amateur has its roots in the French word for love: amour. And amateurs do for love what professionals do for money.

Of course, many professionals love what they do (and are lucky enough to get paid for it), and many amateurs deserve to have the term amateurish applied to their efforts. Having worked in amateur theatre, I know too well how misplaced enthusiasm can override sense resulting in a four-hour panto. But amateurs helped build the world we live in. At the beginnings of the scientific age, scientists themselves were amateurs. They toiled away examining nature to understand why things are the way they are. They invented physics, chemistry and biology.

Although modern science may appear to be the preserve of a well-financed laboratory run by a Nobel-quality mind, the amateur scientist is not on the endangered species list. For example, amateurs play a crucial role in fields where large numbers of observations are needed. There are too many stars, comets and asteroids for only professional astronomers to keep an eye on, so we shouldn't be surprised that Pluto was spotted by an amateur, Clyde Tombaugh, in 1930. And the whole field of radio astronomy got a kick start when, in 1937, amateur Grote Reber built a 9 metre dish in his back garden and plotted the first radio map of the sky.

Keeping track of bird movements and numbers is greatly aided by flocks of amateur ornithologists who report their observations to bodies such as the British Trust for Ornithology, and amateur palaeontologists get in on the act when they uncover new fossils. In 1990, a sociologist uncovered unseen fossilised reptile tracks in New Mexico, much to the surprise of professional scientists.

Even weather forecasting relies partly on amateurs who take thousands of measurements of temperatures and rainfall and report them to the US National Weather Service. Also in the US, the Society for Amateur Scientists helps promote the relationship between professionals and amateurs, showing the hobbyist how to communicate with professionals and how to get their work published and recognised. Its founder, Shawn Carlson, won a MacArthur Foundation "genius award" in 1999 honouring his creation.

Amateurs are also doing well outside the sciences. In popular music, many bands get their start in a garage playing instruments with no formal training. Only very few musicians have spent years in a music academy, yet love for their music has brought us the Beatles, the Stones and every single rapper. Likewise – they help build the world we live in, most authors are amateurs, partly because the money to be made from writing is so poor, and partly because it's hard to get a job as an author. You have to be one to become one. I once asked the writer Alain de Botton about the role of amateurs. He responded nervously that he wouldn't want to be operated on by an amateur brain surgeon, or flown by an amateur pilot. So I steered him back to the safer ground of amateur philosophy.

In any pub in Britain you'll find plenty of Friday-night philosophers waxing lyrical. But even in the world of serious philosophy, amateurs outrank the professionals. Many of the great philosophers were amateurs, from Schopenhauer and Nietzsche to Sartre. De Botton puts this down to university philosophy departments being so poor. But perhaps there's another reason: if there's one subject we all study and can be passionate about, it's the human experience.

So watch out when you're down the pub: you might be sitting beside the next Nietzsche. Or at least a bloke who counts butterflies for the sheer love of it.

• This article was commissioned after Cif was contacted by a commenter in a You Tell Us thread