Political Systems of Highland Burma was first published in 1954, although the edition published a decade later is the more common one due to the presence of a new and intriguing foreword by Leach. The data for the book came from Leach's posting in Burma during the Second World War, during which time he fought with his commanding officers, fled across almost the entirety of Burma, and stayed with local villagers. The area in which he was interested as an anthropologist was away from the principle centres of Burmese civilisation (Mandale, Yangon, etc), up in the highland region near the border with Yunnan.
This region is now known as Kachin State; it was and is inhabited by many ethnic, cultural, and linguistic groups of such entangled ancestry that they can barely be sorted into separate populations. The ethno-linguistic label of 'Kachin', now applied to the entire state, is also used in the subtitle of Leach's book. Among the languages spoken in the region are Kachin, Jinghpaw, Burmese, Shan, Maru, and Atsi. The people of the region are similar culturally, with material, ritual, and political culture varying in ways that don't correlate with the distribution of the different language groups. It's something of an ethnic mélange.
Leach was concerned that theories of society in his time neglected the fundamentally unstable nature of relations between humans. At British universities in Leach's time, structural-functionalism was the dominant theoretical position; this is a (largely cobbled-together) theoretical approach characterised by belief in the equilibrium of society (that society and social facts are stable entities) and in the organic metaphor of society (the view that human societies most closely resemble organisms). This metaphor goes back to the nineteenth century sociologist Herbert Spencer, a man most famous for his development of what we might now call 'social Darwinism' (although Spencer in fact lived and wrote before Darwin). It was then picked up in the work of Emile Durkheim (who needs no introduction), and it was from there that it entered British social anthropology.
As you might expect, an organic metaphor of society emphasises the notion that people are most akin to cells, working for the greater good of the 'organism'/society rather than for themselves. Rather than being individuals motivated primarily by their own beliefs and desires, they work for groups larger than themselves such that there is a predictable, law-like relation between different parts of society. There is equilibrium between the parts. It is arguable whether societies are ever usefully modeled in this way - regardless, this was the dominant position in anthropology at the time, and Leach believed it inapplicable to the situation of the Burmese highlands as he found it.
Instead, the highlands showed a continual fluctuation between two extremes of social structure. Leach tried to use native terms for any societal arrangements he discovered, explaining them in the technical jargon where necessary. Two terms in particular stand out. One, gumsa, meant a system characterised by the increasing influence of a single chief who acquired political, ritual, and economic power through marriages with and recognition from the larger states of the lowlands, especially those of the Shan.* The chief required fealty from highland subordinates and imposed a rigid, hierarchical set of marriage alliances between clans and lineages, as well as a system of bridewealth (hpaga) that imposed a heavy debt-burden.
By contrast, gumlao meant a system that wasn't really a system. Gumlao could be said to represent a deliberately republican form of government, with power distributed between clans, with marriage alliances arranged in much less hierarchical ways, and with a consistent emphasis on the ideal, if not the reality, of equality between inter-marrying clans. It wasn't 'true' egalitarianism, and it shouldn't be imagined that there was an absence of distinction between individuals. It's just that there wasn't a single paramount chief lording it over everyone else, and ideologically speaking, all clans were considered equals (even if their individual members were not). Gumlao villages also deliberately isolated themselves from the protection and extortion of powerful chiefs.
Leach showed that gumsa and gumlao villages were actually the same. What mattered wasn't ethnicity, language group, or anything like that. What mattered was history. Gumlao villages could become subsumed into gumsa chiefdoms governed by the influence of single clans and single chiefs, creating de facto gumsa society, and gumsa chiefdoms/confederations could and did break down into more isolated gumlao village groups. There was a fluctuation between two forms of social organisation, a fluctuation that was quite regular. Leach showed that certain villages could be shown to have oscillated between gumsa and gumlao organisation over the period of a century or so; almost all Kachin villages varied over time between rigid, hierarchical, ritualised arrangements and relatively unrestrictive egalitarian arrangements, at least ideologically. Leach believed on this basis that highland villages were not equilibrious units, and that any theory of society that attempted to grapple with this had to take account of the possibility of disequilibrium. Models had to be produced making sense of it.
In the foreword to the 1964 edition, Leach claimed that it was power that created this disequilibrium. The chiefs or nominal heads of Kachin villages desired power. This desire caused them to attempt to acquire influence and resources, and to impose restrictions on others in their communities, creating gumsa organisation when they were relatively successful. Other people in these communities would resist these power-grabs in their own attempts to attain influence and power or to secure the most favourable situation for themselves, using the rhetoric of gumlao organisation to nip such power grabs in the bud. This would not always work: in some cases the chief would acquire sufficient power - whether through charisma, a surplus of resources, or whatever else - and sam tai sai 'become Shan', meaning that he had the same power as any Shan lord. The cycle would break and the community would enter a new period as neither gumsa nor gumlao, but rather Shan.
In the foreword, Leach described the system as similar to the disequilibrious theories of the nineteenth century Italian economist Vilfredo Pareto. Pareto had used a metaphor derived from Machiavelli to describe predictable disequilibrium, that of the lion and the fox. In The Prince, Machiavelli proposed a model of the contemporary Italian city-states whereby a 'lion' (a strong military leader) would take control of a city and lead it to success in the field against other cities. He would later fall when, failing in the tasks of the 'fox' (the cunning manipulator), he would become unpopular with the nobles of the city, leading to his execution or some similar fate.
A fox would rise in his place - someone who had managed to manipulate the other nobles, or the rest of the populace, into following him. A fox rarely showed the military acumen necessary to expand the power of the city-state, leading to its crushing in the field by city-states led by lions. A lion might then rise again, leading the city to victory, and then being brought down by the scheming of foxes. A kind of super-equilibrium would result from the disequilibrium: no single city-state would come to rule the rest, and there would be a predictable, fluctuating distribution of power among them. The only way to break this cycle would be for one man to possess the attributes of both the lion and the fox.
In a tutorial on Political Systems of Highland Burma, my tutor, R. H. Barnes, asked whether I knew of any earlier precedent. He was unsure as to where Machiavelli had acquired his theory from (or at least, the phrasing of it). A Middle Eastern student had apparently suggested that Ibn Khaldun, a fourteenth century North African scholar, had presaged the theory, but there doesn't seem to be any evidence of this in his writings. I couldn't think of any source at that point, but I thought it would be a good idea to go and re-read The Prince to find out. And on reading it again, the theory's origins seemed relatively clear.
Machiavelli - who spent a great deal of time under house arrest - found solace in reading about ancient history, and was familiar with the classics in a way few people are. In The Prince, he frequently references the life of Lucius Cornelius Sulla, dictator of Rome. Sulla was quite a bloodthirsty chap. He was an excellent military commander (a lion), having fought against and defeated various 'barbarian' peoples. He was also a skillful manipulator (a fox), charming and scheming his way to the top by taking advantage of the weaknesses of others. Machiavelli is quite explicit in telling his audience to be like Sulla: be both a lion and a fox.
Sulla had in fact been described as a lion and a fox in his own lifetime, by an enemy, Gnaeus Papirius Carbo. I discovered this on, of all places, Wikipedia (second paragraph), when I was looking for information and resources on Sulla. Carbo claimed that Sulla was as brave as a lion and as cunning as a fox, and that the latter attributes were the most dangerous (presumably because they were employed against Romans rather than Celts and Germans).
On this occasion, Carbo was heard to say that he had both a fox and a lion in the breast of Sylla [Sulla] to deal with, and was most troubled with the fox.**This seems to suggest that the lion/fox metaphor was reasonably well-established in Rome at the time.
Sulla resigned the dictatorship and disbanded his legions. His commitment to republicanism was strong - it seems as if he wanted to purge Roman society of undesirables rather than acquire absolute power in perpetuity. Sulla's abilities as a killer and manipulator, however, made him a model not only for Machiavelli to espouse but also for other Romans to follow. It is not a coincidence that within a couple of decades of Sulla's rise and fall, two would-be dictators rose: Gnaeus Pompeius Magnus and Gaius Iulius Caesar. (Crassus, third member of the First Triumvirate, was also part of this trend, especially as he was spurred on by hatred of Pompeius and jealousy of Caesar's military victories - but as he was forced to drink molten gold by his Parthian enemies, he didn't get quite as far as Pompeius and Caesar.) These men, from Sulla to Caesar, seem to exemplify Leach's theory.
Sulla provided an example for other power-seekers to follow, but it was only when one appeared who combined the attributes of lion and fox that the cycle was broken (if only temporarily). Caesar defeated the Gauls, Britons, and Germans, crossed the Rubicon with an army, engaged in an inter-continental civil war with Pompeius, manipulated the nobles of Rome into following him, defeated the alliance against him, and founded the Julio-Claudian line, ending the Roman republic.
Caesar's death in the Senate and the resulting machinations of Lepidus, Marcus Antonius, and Octavian were also good examples of the theory. I suppose, in the end, Octavian sam tai sai.
It isn't necessary to endorse the view that the model represents a 'structure' of its own; it certainly isn't 'organic' in the sense of the organic metaphor. Its explanatory value is quite clear: it allows us to go from the desires of individuals to predictions about the social organisations of villages and empires. It's not perfectly precise, and it is barely predictive at all (who could have predicted that Pompey would lack the skills of the fox or the lion?), but it does what a sociological model should do, and that is make some sense of some aspect of human society. In any case, it is rather cool that the germ of it all came from a comment by a relatively unknown consul of Rome, and that after having been churned through the mind of a Renaissance scholar and a mathematical economist, it developed into a disequilibrious theory of society applied to the lives of people in the hinterland between China, India, and the states of Burma.
* The term gumsa actually applies to a compromise developed between the ideals of the Shan, who were much more settled than the 'Kachin' (multi-ethnic highland) peoples, and those of the Kachin themselves. The former lived in states, and the latter preferred a more isolated, egalitarian system. The gumsa system represented a chiefdom-esque compromise between the two.
** The Dryden translation (free to access). 'Sylla' is the transliterated Greek spelling - Plutarch, of course, wrote in Greek.