As one of my new grad students put it: ‘Why are military historians so scared of theory anyway?’ My answer – historically, it was a military historian who best defined theory’s utility and place:
‘Theory cannot equip the mind with formulae for solving problems, nor can it mark the narrow path on which the sole solution is supposed to lie by planting a hedge of principles on either side. But it can give the mind insight into the great mass of phenomena and their relationships, then leave it free to rise into the higher realms of action. There the mind can use its innate talents to capacity, combining them all so as to seize on what is right and true.’ (Carl von Clausewitz, On War, (Howard and Paret trans, Princeton UP, 1989), 578.
Clausewitz scholars will, of course, point out that he was talking about a particularly 19th century German definition of theory here (in translation, in any case). But he did have to explain, to a difficult audience, why theory was useful but not all encompassing. And what a great job he made of it.