Death to Tyrants! (8 page)

A simple example effectively demonstrates the central importance of common knowledge for the solution to coordination problems. Imagine that two generals for the same army, A and B, would like to join forces in order to attack an enemy. Assume, too, that neither general has a sufficient number of soldiers to confront the enemy alone; if either general should bring his soldiers out of their defensive positions without the help of the other general's soldiers, his soldiers would be defeated by the enemy. Before ordering his troops to leave their current positions, general A needs to know three things: first, that general B is committed to the plan of a coordinated strike; second, that general B knows that general A is also committed to the plan; third, that general B knows that general A knows that general B is committed to the plan. If this last link is missing, A might reasonably conclude that B will assume that A thinks that general B is not committed to the plan and consequently that B will not act. Therefore A himself will not act; it would be too risky. Only when he possesses all three pieces on information can general A act with confidence, and obviously general B must have the same information vis-à-vis general A.

The second important point developed by Chwe is that the performance of public rituals generates common knowledge and thus may be helpful in solving various large-scale coordination problems. As one example, Chwe analyzes royal progresses (rituals wherein a king conspicuously and ceremoniously travels throughout his kingdom) conducted in sixteenth-century England, fourteenth-century Java, and eighteenth-and nineteenth-century Morocco.
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Such rituals did not simply provide an opportunity for the king to
demonstrate his power to his subjects; they also were opportunities for each individual in the various crowds to see other individuals in the crowd witness the king's power and grandeur, and each witness also knew that other individuals at other points in the progress, although not directly observed, would see the same thing. It is easy to see how such progresses would help a king maintain control over his subjects: they generate common knowledge both of the king's great power and of the apparently widespread support for his rule.

Chwe's insights suggest that one might profitably interpret the oath of Demophantos as a “rational ritual” that, through the generation of common knowledge, would help Athenian democrats solve a large-scale revolutionary coordination problem. Three aspects of the oath ritual greatly facilitated the generation of common knowledge of widespread commitment to kill tyrants and reward tyrant killers. First each participant was in the presence of the other participants (his fellow tribesmen) and could see that the other participants actually were paying attention to the ceremony. Chwe points out that inward-facing, circular architecture, such as the kivas of New Mexico and the meeting chamber of the city hall in Fort Worth, Texas, helps large numbers of individuals quickly build common knowledge from eye contact.
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We do not know where the Athenians swore the oath of Demophantos. But it is not unreasonable to suppose that they did so in a theater or similar structure; they certainly benefited from the use of such structures in other political activities. Such a setting would have maximized the number of people each individual participant could see. Second, the oath was repeated several times during each tribal ceremony. The importance of repetition for the generation of common knowledge is obvious enough: if a message is repeated several times, everybody knows that everybody else has heard it.
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Third, the expression
καθ᾿ ἱερῶν τελείων
(“over perfect victims”) suggests that the demesmen swore the oath while moving in unison, perhaps in some sort of downward motion. It is also possible that the men touched or held part of the sacrificial victim. Such synchronized movement, if conducted successfully, would demonstrate to both the participants and the rest of their fellow tribesmen that each individual was fully aware of what he and others were doing.
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There are also three reasons to conclude that the widespread commitment to kill tyrants and reward tyrant killers would have been considered largely credible. First, everybody would have known that the
dēmos
does, in fact, reward tyrant killers: statues of Harmodios and Aristogeiton were prominently placed in the agora; the oldest descendants of those two tyrannicides received
sitēsis
one hundred years after that famous act of tyrant killing; and honors were voted not only for the assassins of Phrynichos, but also for each
of their accomplices. Consequently, few Athenians would have doubted a pledge to reward future acts in the same way. Second, everybody knew that individual Athenians had in fact killed or conspired to kill subversive Athenians in the past and that they would presumably do so in the future. The assassination of Phrynichos is the single most conspicuous example, but after that act hundreds of other Athenians—the exact number is unknown—likewise armed themselves in order to kill the supporters of the Four Hundred, if necessary. It would thus be reasonable to believe their pledge to do so again. Third, everybody would have known that the vast majority of Athenians did not reluctantly swear the oath, but rather welcomed the opportunity to publicize their commitment to defend the democracy. After the fall of the Four Hundred, democrats certainly knew that pluralistic ignorance (or, in the words of Thucydides, “being powerless because of their lack of knowledge of one another”) had prevented them from defending their democracy as quickly and effectively as they might otherwise have done. Thus most individuals would have been eager to let their fellow citizens know what they really thought.

Despite the fact that each Athenian probably swore the oath with the other members of his deme in the presence of his fellow tribesmen, and not before the entire citizen body, the cumulative effect of the many separate, tribally organized oath rituals would have been to generate common knowledge that every Athenian was publicly committed to killing tyrants and rewarding tyrant killers. The members of each tribe would have known that the members of the other nine tribes were required to swear the same oath, and likely in the same way. They would have learned that from a variety of sources: the decree of Demophantos, tribal meetings, deme meetings, and casual conversations with individual citizens. It is also important to note that, at the time the Athenians swore the oath of Demophantos, most citizens were living within the city walls because of the Spartan occupation of nearby Dekeleia. It thus would have been virtually impossible for a group activity involving over one thousand men, such as the kind of oath ceremony envisioned here, to pass unnoticed. Consequently, despite the fact that different groups of Athenians swore the oath on ten different occasions, the ultimate effect would have been the same as if all had done so together at the same time.

SOLUTION TO COORDINATION PROBLEM

I have suggested that the Athenians would have been better able to solve a revolutionary coordination problem if it had been common knowledge that a majority of the citizens were credibly committed to killing tyrants and rewarding tyrant killers. Two lines of reasoning support this conclusion.

First, in the postulated post-oath epistemic environment, a “non-bold” individual—one whose revolutionary threshold before the oath was greater than 1—would lower his personal revolutionary threshold and thus take the
risk to defend the democracy earlier than would otherwise have been the case. He would do so, of course, because he would reasonably expect a sufficient number of other individuals to follow him, because he would believe that those other individuals believe that yet others will follow them. The psychological cost of preference falsification would thus overbalance the expected physical cost of public action, making it rational to vigorously defend the democracy. Since, however, nobody can ever be absolutely certain about what other individuals are thinking and thus what they will actually do, a typical democrat would not take the risk to defend the democracy in the earliest stages of an anti-democratic coup; that is, he would not lower his revolutionary threshold to 0. Instead, he might lower it from, say, 4 to 3, or 2 to 1. Other individuals would do likewise. Thus an initial threshold sequence of {1, 2, 3, 3, 4, 4, 5, 6, 8, 10} would, after the oath, become {1, 1, 2, 2, 3, 3, 4, 5, 7, 9}, and the conditions necessary for the emergence of a latent revolutionary bandwagon would be established.

Second, in the postulated post-oath epistemic environment, a “bold” individual—one who, before the oath, had a revolutionary threshold of 1—would lower his revolutionary threshold to 0. Such an individual would know that, if he should go first and “kill a tyrant,” he would receive in return a considerable amount of money (one-half of the amount raised from the sale of the tyrant's assets), in addition to fame and honor. He would also know that, should he die attempting to kill the tyrant, he would become even more esteemed among his fellow citizens, who would likely honor him with a statue, and his children would be cared for by the state. Such positive, selective incentives, however, regardless of their credibility, might not be enough to entice such individuals to go first if they believed that the movement they were initiating might fail. But when those incentives are presented within an epistemic context of common knowledge of widespread credible commitment to defend the democracy, the bold individual can safely conclude that others will in fact follow him. It would be rational, therefore, to take the risk, in the confidence that such an action would spark a revolutionary bandwagon.
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It is thus reasonable to conclude that, as a result of the fact that all Athenians swore the oath of Demophantos, the democrats would in the future be more likely to overcome a potentially debilitating revolutionary coordination problem and mobilize en masse against a nondemocratic regime. Imagine a hypothetical situation in which oligarchs once again relied on intimidation and disinformation in order to overthrow the democracy and maintain control of the state. If no precaution had been taken, a revolutionary coordination
problem might prevent the numerically superior democrats from responding. But now that the Athenians had sworn the oath of Demophantos, a bold individual who had recently lowered his revolutionary threshold from 1 to 0 would be much more likely to go first, in the expectation that other individuals would follow him. Someone who had recently lowered his revolutionary threshold from 2 to 1 would follow him, and so on. Thus the Athenians would be able to replicate (mutatis mutandis) the sequence of events that brought down the Four Hundred: a spark (the assassination of Phrynichos) setting in motion a bandwagon (the uprising in the Piraeus), followed by a large-scale coordinated action (the meeting in the theater of Dionysos at Mounichia and the subsequent march on the city).

The oath of Demophantos was not the first Athenian attempt to legislate against tyranny, and at this point one might ask why the protections in place before the coup of the Four Hundred failed. Several earlier measures against tyranny are known, all presumably intended to ensure quick action in defense of the democracy.
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•  An old law of uncertain date against aiming at tyranny or assisting someone in an attempt to become tyrant (
Ath
.
Pol
. 16.10).
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•  A prayer-cum-curse against individuals contemplating tyranny and anyone who might help them (Ar.
Thesm
. 335–39), possibly articulated at the beginning of sessions of both the
boulē
and the
ekklesia
.

•  A traditional proclamation likely announced at the beginning of the Dionysia, which promised a talent for anyone who “kills a tyrant” (Ar.
Av
. 1072–75).
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•  A provision in the heliastic oath (Dem. 24.149) against voting for tyranny or oligarchy.

•  A possible provision in the bouleutic oath against voting for tyranny or oligarchy (Dem. 24.144).
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•  The state-maintained hero cult for Harmodios and Aristogeiton should perhaps also be included here, since its clear purpose was to encourage others to act as tyrannicides.
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It is likely that that these measures were ineffective because they did not convince individuals that, should they act to defend the democracy, others would follow. That guarantee is a key element in the oath of Demophantos, by which every Athenian individual pledged to act, to kill “by word and deed, by vote and by my own hand whoever overthrows the democracy at Athens.” None of the aforementioned mechanisms articulated that important commitment. The law against tyranny simply declared that a tyrant would be pronounced
atimos
(and thus could be killed with impunity). The prayer-cum-curse requests only that the gods punish a tyrant or an aspiring tyrant. The proclamation at the Dionysia just promises to give a tyrant killer a talent. An individual swearing the heliastic oath (and perhaps the bouleutic oath) simply pledged “not to vote for tyranny.” The honors for Harmodios and Aristogeiton offered only the prospect of similar rewards to subsequent tyrannicides. None of these measures did anything explicit to convince a would-be tyrant killer that others would follow his lead. A bold individual would thus question whether or not he should take the all-important first step to protect the democracy.

Thucydides's explanation for the panic of the Athenians after the mutilation of the Herms (6.53.3) supports the interpretation offered here: “For the
dēmos
, knowing by tradition that the tyranny of Peisistratos … had been put down, not by themselves and Harmodios but by the Lakedaimonians, were in constant fear and regarded everything with suspicion.” The Athenians were clearly afraid that they would be unable to protect their regime against a future coup. If that view was commonly held, as Thucydides suggest, it would have been reasonable to suppose that a typical person would not fight to defend the democracy unless many had already done so. Thus a bold individual, unsure whether or not his fellow citizens were committed to act, would choose not to go first: despite the many measures against tyranny, he would not believe that a sufficient number of people would follow him. As a result, nobody would attempt to start a revolutionary bandwagon.
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