Picasso once noted that "when art critics get together they talk about Form and Structure and Meaning. When artists get together they talk about where you can buy cheap turpentine." When you practice a craft you become skilled and knowledgeable in two areas: the stuff the craft produces, and the processes used to create it. And the second kind of expertise accumulates much faster. I call this the turpentine effect. Under normal circumstances, the turpentine effect only has minor consequences. At best, you become a more thoughtful practitioner of your craft, and at worst, you procrastinate a little, shopping for turpentine rather than painting. But there are trades where tool-making and tool-use involve exactly the same skills, which has interesting consequences. Programming, teaching, writing and mechanical engineering are all such trades.
Self-Limiting and Runaway Turpentine Effects
Any sufficiently abstract craft seems to cause some convergence of tool-making and tool-use. Painters aren't normally also chemists, so that's actually not a great example. But I don't doubt that some of Picasso's forgotten technician contemporaries, who had more ability to say things with art than things to say, set up shop as turpentine sellers, paint-makers or art teachers. But in most fields the turpentine effect is self-limiting. As customers, pilots can only offer so many user insights to airplane designers. To actually become airplane designers, they'd have to learn aerospace engineering. But in domains where tool-making involves few or no new skills, you can get runaway turpentine effects.
As Paul Graham famously noted, hackers and painters are very similar creatures. But unlike painting or aircraft, programming is a domain where tool-use skills can easily be turned into tool-making skills. So it is no surprise that programmers are particularly susceptible to the runaway turpentine effect. Joel Spolsky struck me very forcefully as the runaway-turpentine-effect type, when I read his Guerrilla Guide to Interviewing (a process designed to allow technically brilliant programmers to clone themselves). It is no surprise that his company produces tools (really good ones, I am told) for programmers, not software for regular people. And their hiring process is guaranteed to weed out (with rather extreme disrespect and prejudice) anyone who could get them to see problems that are experienced by non-programmers. 37 Signals is another such company (project management software). If you see a tool-making company, chances are it was founded entirely by engineers. And the consequences aren't always as pretty as these two examples suggest.
Linus Torvalds' most famous accomplishment was an act of thoroughly unoriginal cloning (Unix to Linux, via Minix). But among programmers, he seems to be most admired for his invention of git, a version control system whose subtle and original design elements only programmers can appreciate. This discussion with a somewhat postal Torvalds comment (I hope it is authentic) is a revealing look at a master-tool-maker mind. Curiously, Torvalds is going postal over a C vs. C++ point, and it is interesting to read his comment alongside this interview with another programmer's programmer, Bjarne Stroustroup, the inventor of C++.
Eric Raymond codified, legitimized and spiritualized this path for programmers, in The Cathedral and the Bazaar, when he noted that most open-source projects begin with a programmer trying to scratch a very personal itch, not "other-user" needs. The open source world, as a result, has produced far more original products for programmers than for end users. Off the top of my head, I actually can't think of a single great end-user open source product that is not a clone of a commercial original (aside: there is a crying need for open-source market research).
When I was a mechanical engineering undergraduate, my computer science peers created a department t-shirt that said "I'd rather write programs to write programs than write programs." That about sums it up. In my home territory of mechanical engineering, some engineers naturally like to build machines that do useful things. Others build machine tools, machines that build machines, and wouldn't have a raison d'etre without the first category.
Next door to programming and engineering, the turpentine effect can occur in science as well. Stephen Wolfram is my favorite example of this. His prodigal talents in physics and mathematics are probably going to be forgotten in 50 years, because he never did anything worthy of them (according to his peers, neither his early work, nor A New Kind of Science, is as paradigm-shattering as he personally believes). But the paradigm-shifting tool he built, Mathematica, is going to be in the history books much longer.
Teaching is a very basic creative skill that seems to emerge through runaway turpentine effects. I knew a professor at Cornell who had, outside his door, a sign that said, "Those who can, do. Those who can do better, teach." Methinks the professor doth protest too much. There is a reason the actual cliche is "those who can, do. Those who can't, teach." But the insinuation that teachers are somehow not good enough to "do" is too facile. That is often, but not always, the case.
What happens is that all talented people engage in deliberate practice (a very conscious and concentrated form of self-aware learning) in acquiring a skill. But if you can't find (or get interested in) things to do that are worthy of your skill, you turn to the skill itself as an object of attention, and become better at improving the skill rather than applying it. Great coaches were rarely great players in their time. John Wright, a mostly forgettable cricket player, had a phenomenal second innings in his life, as the coach who turned the Indian cricket team around.
But this effect of producing great teachers has a dark side as well, especially in new fields, where there are more learners than teachers. Thankfully, despite being tempted several times, I never started a "how to blog" blog. More generally, this is the writing/speaking/teaching/consulting (W/S/T/C) syndrome that hits people who go "free agent." We talked about before in my review of One Person, Multiple Careers (check out the comments as well).
This relation to teaching (via self-learning) has actually been studied in psychology. In Overachievement, John Eliot talks about a 'training' mindset and a 'performance' mindset. The former involves meta-cognition and continuously monitoring your own performance. The latter involves an ability to shut off the meta-cognition and just get lost in 'doing'. Great teachers were probably great learners. Great doers may be slower learners, but are great at shutting off the meta-cognition.
Causes and Consequences
I think the turpentine effect is caused by -- and I am treading on dangerous territory here -- the lack of a truly artistic eye in the domain defined by a given tool (so it is ironic that it was Picasso who came up with the line). Interesting art arises out of a combination of refined skills and a peculiar, highly original way of looking at the world through that skill. If you have the eye without the skills, you become an idiosyncratic eccentric who is never taken seriously. If you have the skills without the eye, you become susceptible to the turpentine effect. The artistic eye is innate and requires no real refinement. In fact, the more you learn, the more the eye is blinded. The adult artistic eye is largely a matter of protecting a childlike way of seeing, but coupling it to an adult way of processing what you see. And to turn it into value, you need a second coupling to a skill that translates your unique way of seeing into unique ways of creating.
There is a feedback loop here. Sometimes acquiring a skill can make you see things you didn't see before. When you have a hammer in your hand, everything looks like a nail. On the other hand, if you can't see nails, all you see is opportunities to make better hammers.
The artistic eye is also what you need to make design decisions that are not constrained by the tools. A complete absence of artistic instincts leads to an extreme lack of judgment. In a Seinfeld episode, Jerry gets massively frustrated with a skilled but thoroughly inartistic carpenter whom he has hired to remodel his kitchen. The carpenter entirely lacks judgment and keeps referring every minor decision to Jerry. Finally Jerry screams in frustration and tells him to do whatever, and just stop bothering him. The result: the carpenter produces an absolute nightmare of a kitchen. In Wonderboys, (a movie based on a Michael Chabon novel) the writer/professor character played by Michael Douglas tells his students that a good writer must make decisions. But he himself completely fails to do so, and his book turns into an unreadable, technically-perfect, 1000-page monster. No artistic decisions usually means doing everything rather than doing nothing. Artists mainly decide what not to do.
What about consequences?
The most obvious and important one is a negative consequence: creative self-indulgence. Nikki Hilton designs expensive handbags (which is still, admittedly, a more admirable way of spending a life than the one her sister models). There is a reason most product and service ideas in the world are created for and by rich or middle-class people for their own classes. The turpentine effect is far more prevalent than its utility requires. There is a limit to how many people can be absorbed in safe and socially-useful turpentine-effect activities like tool-building or teaching. Let loose where a content-focus, artistic eyes and judgment are needed, it leads to over-engineered monstrosities, products nobody wants or needs, and a massive waste of resources. Focusing on the problems of others, rather than your own (or of your own class), requires even more effort.
The positive effects are harder to see, but they are important. The turpentine effect is how isolated creatives can get together and form creative communities that help refine and evolve a discipline, sometimes over centuries, and take it much further than any individual can. Socially, this emerges as the aesthetic of classicism in any field of craft.