Peter Heather, The Fall of the Roman Empire: Chapter 3, "The Limits of Empire"

Heather starts with the story of a corruption scandal in Lepcis Magna in the late 4th century -- a Roman general refuses to protect the town without bribes, an imperial delegate sent to investigate is suborned, with his own corruption used as leverage against him. This sort of thing, Heather says, is often taken as evidence of late Roman decline. But he casts doubt on this interpretation, citing sources which show that self-aggrandizement and advancement through connections were endemic and even expected in Roman government going back at least to the late Republic.

He draws another lesson from the story: because of the scale of the empire and the limits it imposed on communication, imperial rule was always episodic and superficial. Most of the empire was always several weeks journey away from an imperial court, so the emperor would have few points of contact with or sources of information from distant provinces (and even if more information had been available, the filing system of Roman officials wasn't up to the task of making it usable). Heather reiterates this point with documents from the journey of the early 4th century Roman bureaucrat Theophrastes from Egypt to Antioch demonstrating the slow pace of travel and the limits in regular contact between officials in different provinces.

Heather then takes up the question of whether late Roman society was overburdened by the costs of the 3rd century military buildup. Until a few decades ago, this was the settled view, supported by a broad collection of evidence: decline in inscriptions, decreased willingness to serve in local offices (flight of the curials), laws binding agricultural workers to estates, appearance of references to empty lands in texts.

Heather says this conflicts with recent archaeological evidence (starting with George Tchalenko's investigations of Antioch's hinterlands in the 1950s) that show rural settlement reaching or sustaining its peak level throughout most of the empire in the 4th century (with Italy being the most significant exception). He proceeds to explain away the evidence for a decline: the empty lands cited in documents may never have been settled, restrictions on the mobility of agricultural workers were only enforceable when population density was high, and the fall off in inscriptions and local political participation reflect a shift in the location of interesting positions to the imperial bureaucracy.

After this, Heather looks at the case, put forward most famously by Gibbon, that Christianity diverted resources from productive use and sapped allegiance to the empire. He notes that pre-Christian religious cults also absorbed a lot of resources, so that it isn't clear that this issue was any more significant in a Christianized empire. Moreover, Christianity quickly adapted to ideologically supporting the legitimacy (and even the divine blessing) of imperial rule. The state's ability to entice elites to Christianize in order to advance in official posts shows that the influence of the center had not, in fact, been diminished.

Heather concludes with a discussion of some limitations of imperial Roman government (riffing off the Senate's reception of the Theodosian code). Foremost among these is the added instability and tension from the logistical and administrative requirement for two relatively equal emperors, especially since no firm system of succession was ever worked out. Heather points to ideological conformity as another weakness, although it is not clear why he thinks this is an actual source of weakness of the state rather than just something unpleasant. Finally, he points to the effective restriction of political engagement to a small landed elite and the concomitant focus of the state in serving the needs of that elite. He suggests that this left the vast laboring agricultural majority indifferent to the Roman state, and the allegiance of the landowning elite up for grabs when the state failed to offer protection for their property.