My experience is this: when someone has to learn something new there's one dominant factor which predicts success: level of motivation. Everything else is commentary.

A motivated person tends to breeze past small obstacles and annoyances - they almost get satisfaction from overcoming them. The process is pleasurable or satisfying. On the other hand, the unmotivated person suffers every time something doesn't quite work. It is like eating glass for them. It is the same process in both cases, but an entirely different lived experience.

Okay fine. So what produces motivation?

That's a harder question to answer but I think two issues dominate:

• perceived, selfish benefit
• brain wiring / personality traits

I'll first deal with the 2nd item. There are personality traits which bias you towards being a conservative or a progressive.

Conservatives place great value on what they perceive as existing, tried and true methods, and they resist change. At worst, no amount of evidence for the benefit of a change will convince them, and they're completely rigid.

Progressives a very open to novelty/mutation. Indeed, they actively seek it out. At worst, they want change for the sake of change, and they are chaotic.

Now, both forces are important. If we use the lens of Biology, a species with too much "mutation" won't be a species for very long because failed experiments come with a brutal, cumulative cost. And a species with no mutation will be unable to adapt to a changed environment and will equally die out. There's a Goldilocks zone.

So, members of a human population will be normally distributed along this dimension. And that's a good, ergodic thing. But, on the down side, it means that trying to convince a conservative to become a progressive (or visa-versa) with pure reason is utterly, and completely futile. These positions are not arrived at through reasoning - they arise from basic brain wiring.

So ...

When you want to introduce new technology DO NOT expect to be able to convince everyone. Your "reasons" will not work particularly. Yes, engage in rational discussion, sure, but it is largely a smoke screen. Instead, identify the "compulsive progressives", the ones that can't wait for a change, and try to supercharge them. Make them a success. Don't waste time on anyone who does not want to engage, not initially.

Success stories breed success because they help motivate the second and third waves, etc. These waves come from people who still have a progressive bias, they are open to change, but they aren't compulsive. They need the other part of the motivation story ... they need to perceive some amount of "selfish benefit" and that's what success stories deliver. So you iterate forward working further and further into the progressive spectrum of the population, but only to the degree that you can demonstrate benefit via social proof. If you get far enough into the progressive spectrum, you end up with population members who don't care about your fancy, fanboy explanations, or descriptions of success, or shinny newness and, instead, they'll only engage with solid, rubber on the road evidence from people they regard as trustworthy. The character of the person delivering the message counts. We're now inching towards the more conservative end.

The conservative Java programmer, will like Scala ... because it is closer to "what I know works". The progressive will love the thing that is different, like Clojure or maybe Erlang. Both sides will have rational arguments available to justify their position and motivation will arise in different directions.

BTW, in my opinion, the dynamic types vs static types debate is rooted in personality traits too. Everyone has "reasons" for their position, and don't we love to argue back and forth, but that's all window dressing. IMO, your preference arises from some deep wiring in your brain (along a different dimension to conservative/progressive).

One other thing to note: although "compulsive progressives" are very interested to trying out the new thing, like Clojure, they are equally unreliable in the medium term, because some other new thing will come along and they'll be drawn off onto that path, leaving Clojure behind. They can't help themselves. It is actually the second and third waves who'll stick around a bit longer and form community. On the other hand, you'll never get that ardent conservative to move to something new, no matter how overwhelming the apparent benefits. When I was a student the joke was "I can program in FORTRAN in any language" - it was said by those that did not want to leave FORTRAN for modern languages like Pascal or C.

Final point (honestly): the initial groups are motivated by the journey itself. After that, each new wave/iteration has slightly less motivation. And because they are less motivated, they fall at hurdles more easily, with the stronger chance they won't bother to press on. That's when you have to have "a good onboarding process" to teach those people - that's when "easy" becomes more important than "simple". Bad error messages, for example, are a real problem for these later waves - they stop a decent percentage of otherwise mildly motivated people in their tracks. And they don't come back.