Theory P or Theory D?

Which theory fits the evidence (Raganwald):

Theory P adherents believe that there are lies, damned lies, and software development estimates. ... Theory P adherents believe that the most important element of successful software development is learning.

Maybe I'm an extreme P adherent; I say that learning is everythingin software development.  The results of this learning are captured incode where possible, human minds where not.  Absolutely everything elseassociated with software development can and will be automated away.

Finally:

To date, Theory P is the clear winner on the evidence, and it’s noteven close. Like any reasonable theory, it explains what we haveobserved to date and makes predictions that are tested empiricallyevery day.

Theory D, on the other hand, is the overwhelming winner in themarketplace, and again it’s not even close. The vast majority ofsoftware development projects are managed according to Theory D, withlarge, heavyweight investments in design and planning in advance, verylittle tolerance for deviation from the plan, and a belief that goodplanning can make up for poor execution by contributors.

Does Theory D reflect reality? From the perspective of effectivesoftware development, I do not believe so. However, from theperspective of organizational culture, theory D is reality, and youignore it at your peril.

So this is a clear contradiction.  Why is it that theory D is sosuccessful (at replicating itself if nothing else) while theory Planguishes (at replicating)?  Perhaps D offers clear benefits to itsadherents within large organizations -- status, power, large reportingtrees...  and thus P can't gain a foothold despite offering clearorganization-level benefits. 

But I suspect that it's simpler than that; I think that people simplydon't really evaluate history or data objectively.  Also, it may bedifficult for people without the technical background to really howdifficult some problems are; past a certain level of functionality,it's all equally magic.  The size of the team that accomplished a taskthen becomes a proxy for its level of difficulty, in the way that highprices become a proxy for the quality of a product in the marketplacefor the majority of consumers.  So small teams, by this measure, mustnot be accomplishing much, and if they do, it's a fluke that can beexplained away in hindsight with a bit of work.

Somebody should do a dissertation on this...

Tags: software development, theory p, theory d, statistics, evidence, process