This week, we’re looking at the Roman Senate, an institution so important that it is included alongside the people of Rome in the SPQR formulation that the Romans used to represent the republic, and yet also paradoxically it is an institution that lacks any kind of formal legal powers.

Despite that lack of formal powers, the Senate of the Roman Republic largely directed the overall actions of the republic, coordinating its strategic policy (both military and diplomatic), setting priorities for legislation, handling Rome’s finances and assigning and directing the actions of the various magistrates. The Senate – not the Pontifex Maximus¹ – was also the final authority for questions of religion. The paradox exists because the Senate’s power is almost entirely based in its auctoritas and the strong set of political norms and cultural assumptions which push Romans to defer to that auctoritas [the Mos maiorum].

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We should start with who is in the Senate. Now what you will generally hear in survey courses is this neat summary: the Senate had 300 members (600 after Sulla) and included all Romans who had obtained the office of the quaestorship or higher and its members were selected by the censors. And for a basic summary, that actually serves pretty well, but thinking about it for a few minutes one quickly realizes that there must be quite a bit of uncertainty and complexity underneath those neat easy rules. And indeed, there is!

First we can start with eligibility by holding office. We know that in the Sullan constitution, holding the quaestorship entitled one into entrance into the Senate. Lintott notes that the lex repetundarum of 123/4 lumped every office aedile-and-above together in a phrasing “anyone who has or shall have been in the Senate” when setting eligibility for the juries for the repetundae courts (the aim being to exclude the magistrate class from judging itself on corruption charges), and so assumes that prior to Sulla, it was aediles and up (but not quaestors) who were entitled to be in the Senate.² The problem immediately occurs: these higher offices don’t provide enough members to reach the frequently attested 300-Senator size of the Senate with any reasonable set of life expectancies.

By contrast, if we assume that the quaestors were enrolled in the Senate, as we know them to have been post-Sulla (Cicero is a senator for sure in 73, having been quaestor in 75), we have eight quaestors a year elected around age 30 each with roughly 30 years of life expectancy³ we get a much more reasonable 240, to which we might add some holders of senior priesthoods who didn’t go into politics and the ten sitting tribunes and perhaps a few reputable scions of important families selected by the censors to reach 300 without too much difficulty. The alternative is to assume the core membership of the Senate was aediles and up, which would provide only around 150 members, in which case the censors would have to supplement that number with important, reputable Romans.

To which we may then ask: who might they choose? The obvious candidates would be … current and former quaestors and plebeian tribunes. And so we end up with a six-of-one, half-dozen of the other situation, where it is possible that quaestors were not automatically enrolled before Sulla, but were customarily chosen by the censors to “fill out” the Senate. Notably, when Sulla wants to expand the Senate, he radically expands (to twenty) the number of quaestors, which in turn provides roughly enough Senators for his reported 600-person Senate.

That leads us to the role of the censors: if holding a sufficiently high office (be it the quaestorship or aedileship) entitles one to membership for life in the Senate, what on earth is the role of the censors in selecting the Senate’s membership? Here the answer is in the sources for us: we repeatedly see the formula that the meetings of the Senate were attended by two groups: the Senators themselves and “those who are permitted to state their opinion in the Senate”. Presumably the distinction here is between men designated as senators by the censors and men not yet so designated who nevertheless, by virtue of office-holding, have a right to speak in the Senate. It’s also plausible that men who were still iuniores might not yet be Senators (whose very name, after all, implies old age; Senator has at its root senex, “old man”) or perhaps men still under the potestas of a living father (who thus could hardly be one of the patres conscripti, a standard term for Senators) might be included in the latter group.

In any case, the censors seem to have three roles here. First, they confirm the membership in the Senate of individuals entitled to it by having held high office. Second, they can fill out an incomplete Senate with additional Roman aristocrats so that it reaches the appropriate size. Finally, they can remove a Senator for moral turpitude, though this is rare and it is clear that the conduct generally needed to be egregious.

In this way, we get a Senate that is as our sources describe: roughly 300 members at any given time (brought to the right number every five years by the censors), consisting mostly of former office holders (with some add-ons) who have held offices at or above the quaestorship and whose membership has been approved by the censors, though office holders might enter the Senate – provisionally, as it were – immediately pending censorial confirmation at a later date. If it seems like I am giving short shrift to the “filling the rank” add-ons the censors might provide, it is because – as we’ll see in a moment – Senate procedure combined with Roman cultural norms was likely to render them quite unimportant. The role of senior ex-magistrates in the Senate was to speak, the role of junior ex-magistrates (and certainly of any senator who had not held high office!) was to listen and indicate concurrence with a previously expressed opinion, as we’re going to see when we get to procedure.

Bret Devereaux, “Collections: How to Roman Republic 101, Part IV: The Senate”, A Collection of Unmitigated Pedantry, 2023-09-22.

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1. I stress this point because this is a common mistake: assuming that the Pontifex Maximus as Rome’s highest priest was in some way the “boss” of all of Rome’s other priests. He was not; he was the presiding officer of the college of Pontiffs and the manager of the calendar (this was a very significant role), but the Pontifex Maximus was not the head of some priestly hierarchy and his power over the other pontifices was limited. Moreover his power over other religious officials (the augures, haruspices, the quindecimviri sacris faciundis and so on) was very limited. Instead, these figures report to the Senate, though the Senate will generally defer to the judgment of the pontifices.

2. With sitting tribunes able to attend meetings of the Senate, but not being granted lifelong membership.

3. A touch higher than the 24 years a L3 Model West life table (what we generally use to simulate Roman populations) leads us to expect, but then these are elites who are likely to be well nourished and not in hazardous occupations, so they might live a bit longer.