<論説>ローマ五賢帝政治の成立

Abstract

紀元九六年のネルワ帝即位に始まるローマの所謂五賢帝時代は、帝国の内外が安定した全盛期といわれるが、とりわけその国内政治における安定の要因としては、養子皇帝制の創始や皇帝と元老院の協調が注目されてきた。本稿は、ネルワやその後継者トラヤヌスばかりでなく、彼らと対比される「暴君」ドミティアーヌスの政治をも分析し、国内政治の安定が如何にしてあるいはどのようなものとして確立されたのかという問題を考察しようとしたものである。そこでは、養子皇帝制は実体のないものとして示され、また皇帝と元老院の関係についても、国制上の問題ばかりでなく、政治的支配層としての元老院議員階層の動向にも注意が向けられている。そして考察の結果として、次のことが明らかになった。即ち、社会的流動性というローマ社会の特質をふまえて、帝国全域にわたる有力者の政治参加を積極的に可能とする体制の明確な誕生、あるいは「父祖の遺風」を規範とするローマ社会のもつ政治的伝統と拡大しきった大帝国の社会的現実から生まれる新しい政治的要素との調和、こうしたものが国内政治安定の重大な要因であり、かかる観点から内政上の安定を実現した政治体制を「ローマ五賢帝政治」と呼ぶならば、それはネルワ帝においてではなく、トラヤヌス帝治世初期において成立したとみることが出来るのである。

Under the rule of the Five Good Emperors, the Roman world enjoyed a period of unexampled prosperity and peace, and the political situation in the Empire was pretty stable. How could the Roman Empire achieve this political stability? In this article, we try to examine this question and reconsider the significance of the beginning of the Age of the Five Good Emperors in the political and social history of the Roman Principate. In 96 A. D. Roman Emperor Domitian was assassinated and M. Cocceius Nerva was proclaimed emperor. Domitian is generally depicted as a tyrant, but on the other hand Nerva is regarded as a good emperor who was in harmony with the Senate and inaugurated a new system of succession (Adoptivkaisertum). But our detailed study can show that under the short reign of Nerva there was the antagonism of the Domitianic party against the anti-Domitianic, and that the political situation didn't become stable yet. And our another study has already shown that Trajan's adoption by Nerva in 98 was not the inauguration of a new system of succession but a result of political strife. So, what is difference of the politics of Nerva and Trajan from that of Domitian? Our arguments are as follows. In the first century, the new aristocracy from the Italian and provincial cities gradually engaged in the central government. Domitian positively opened the imperial offices to them with no regard to the traditional group in the Senate. He was an eminent administrator, but in concert with his strong desire for fame this positive policy provoked antipathy of the traditional and conservative group. As for Nerva, he formed a kind of the gerontocracy which can be regarded as a reaction to Domitian's policy. The politics which could achieve the political stability was at length formed in the early years of Trajan's reign; having a high regard for the political and social tradition, Emperor Trajan employed the new power to the imperial administration properly. In sum, the Politics of the Five Good Emperors, which was really established in the reign of Trajan, can be characterized by the formation of the system under which the distinguished in the whole Empire could participate in the imperial government.