You encounter a lot of different personalities in academia, but when you get right down to it they all seem to fall under three basic stereotypes.
OK, I admit it's a gross over-simplification, but here we go:
The young gunYoung guns are the change-makers of academia: the people who want to change anything that doesn't work and replace it with something better -- or at least something different that can be tried out and tested to see if it is better. This often makes them talented researchers (although not necessarily more so than stalwarts, the next stereotype), but they're typically found in larger groups, taking on larger projects and collaborations.
Young guns can be of any age. They tend to be young, of course -- often junior staff who are keen and un-jaded, who want to move their discipline forward and teach it as well as it can be taught. They're often found pushing for new modules, new degrees, new ways of teaching and assessment -- and for promotion. But they don't have to be calendar-years young: the gun-iest young gun I've ever met was in his late 40s when I first went to work for him, is now approaching retirement, and still has more ideas and energy than most people a third his age. These people feel young even when they aren't.
As is probably apparent, young guns can be hell to work with, since for them everything is potentially up for grabs. They're often (but not always) better at idea-forming than at execution, and often (but not always) lack the long-term detail-orientation to make sure that their ideas work out. They are often (but not always) egotists, who may not recognise when a change they've become passionate about is wrong or not working. But without them there's no-one to drive change forward and make sure that schools and disciplines stay fresh and relevant.
The majority of people in academia are stalwarts: people who have clear ideas about the things they want to do and how to do them, but are essentially positive about their activities. They might not lead change, but they'll row-in alongside if they like it and will accommodate to anything that's broadly agreed.
This applies equally to teaching and research. The typical stalwart will teach modules carefully, perhaps changing the content and delivery only slowly if left to their own devices but being perfectly open to updating to include new ideas. In research they will typically be found slightly off the mainstream with a small group of students (often only one at a time), not going for large grants or big collaborations but being solid supervisors and contributors at a small-to-medium scale. Often they come up with great ideas, because they pursue a line of research solidly over a long period and so become world experts. The ideas might not be widely circulated, and so it's easy to underestimate the sophistication stalwarts bring to their work. They may need prodding to publish appropriately, but they'll then address tat problem as effectively as everything else they do.
Stalwarts are essentially positive people, working within a well-defined comfort zone. They are the backbone of any research project or school, and need to be appreciated and rewarded appropriately. They also need to be listened to carefully, since they provide a stability and a sanity that young guns often lack, and will make sure that changes are properly thought through and executed upon.
The twisted nay-sayer
The first two stereotypes are basically positive, but it all goes down hill with the third: the twisted nay-sayer. (I can't claim credit for the great name, incidentally, which is due to Paddy Nixon.) Twisted nay-sayers oppose all change, no matter of what kind and no matter how motivated, and will to continue to oppose changes even long after the decision has been made and the time for action has passed.
On first acquaintance, a twisted nay-sayer often seems to be someone who's stuck-in-the-mud, after an easy life, and not wanting to have the hassle of changing -- a bit like a rather negative stalwart. But this is to overlook the twisted part, which will not only avoid change but actively scheme against it, or to reverse it afterwards. It's this essential negativity that sets this type apart from others. They can, perhaps surprisingly, be excellent researchers, but they'll also be constantly highlighting their successes to anyone who'll listen, even when those successes are long in the past. When faced with a new field or innovation they'll point out that it's really just a poor re-discovery of something that was current years ago, or just an instance of some pet area of theirs that the new innovators should really have found out more about.
The two things to remember about twisted nay-sayers are that they are egotists, and that they are made, not born -- the young gun's dark shadow. You make them by thwarting the expectations they have for their careers. This can happen in two ways: either their expectations were unreasonable, and reality has intruded; or their expectations were completely reasonable but were thwarted by circumstance, malice or indifference. A particularly common case is someone who's been repeatedly passed over for a promotion they think (rightly or wrongly) that they deserve. The repeated denial of their aspirations eventually causes them to give up, turn their back on the future they can't have -- and then rail against fate and everything that comes afterwards.
How, then, are we to deal with the different kinds of academics? Most people fall into some compromise between categories (stalwart with young-gun moments, for example), but clearly one needs to understand an individual's primary motivations in order to know where they're coming from. I think the trick is to make sure a school keeps, listens to -- and occasionally reins-in -- its young guns; recognises and rewards its stalwarts; and tries hard not to grow any twisted nay-sayers.
All these activities are fraught with danger -- especially in academia, where we lack most of the levers of control that normal organisations have. A school can't typically promote on its own recognisance. Not promoting those who feel they deserve it risks overlooking a young gun and having them leave, or (worse) stay, but mutate into a twisted nay-sayer. On the other hand, many promotion boards over-value their young guns and ignore their stalwarts, who then feel under-recognised. Doing so can destroy the stability of a school and can lead fragmented research programmes, and to teaching being good at the edges but lacking a proper core. It's also worth remembering that some people in senior academic positions are extremely conflict-averse and so will cave-in to pressure from twisted nay-sayers in the interests of consensus -- not realising that consensus is neither possible nor desirable, and that acquiescing will only lead to more obstructionism, because it's about the obstruction, not the particular issue at hand. It takes confidence to say yes to experimental change -- but equally it takes confidence to say no when necessary.