Events show that the Senate decided to fight Philip, but no authoritative statement supplies the reason. Thus the ground has been left free for modern historians to suggest the motives of Roman policy, which has been expounded as varying between the extremes of pure altruism and unscrupulous Machiavellianism. Two fundamental points are clear. First, the people did not want war. Their objection was natural enough: their numbers were depleted, agriculture was almost ruined, taxes were high, and they needed rest after the Hannibalic War. Secondly, there was little, if any, legal sanction for the war. The ius fetiale only allowed wars in defence of the state or of her oathbound allies (socii), while now the appellant peoples – Rhodes, Pergamum, Aetolia, and perhaps Egypt and Athens – were probably only amici, and some not even that, on whose behalf Rome was not bound to intervene. Rome had bound herself to her Italian socii by permanent foedera by which the ally supplied an annual military contingent and was not allowed to maintain neutrality. But in Greece and the east she found a different type of alliance: temporary alliance for a definite purpose and friendship in peacetime with the right to maintain neutrality. So Rome had adapted herself to her environment and had entered into relations of friendship (φιλία amicitia) with various states (e.g. with Egypt in 273 BC). Neither party was to fight the other; neutrality, if desired, must be respected; mutual help was not obligatory; such help, if supplied, would not be subordinate to Roman commanders, as were the contingents from socii; amici were formally enrolled but not by treaty. Now that Rome had adapted herself to Greek customs in dealing with Greek states, the question was raised: What was the position of amici in fetial law? When this was referred to the fetial priests it was decided to disregard the distinction between amici and socii, and for the occasion to extend the provisions of the ius fetiale over the amici. A phrase which had no legal standing was coined – socius et amicus – and the law was stretched a point to meet a present need.8 But though perhaps by the Senate’s wish the legal and religious difficulties were met, Rome did not in fact need to intervene on behalf of her ‘friends’ unless she so willed. Why then did she intervene?
The first and most obvious explanation is that Rome started a policy of systematic conquest: aggressive imperialism and militarism were the keynotes of the day. This theory, particularly in so far as it envisages desire for territory as Rome’s object, must be rejected. After the Hannibalic War Rome annexed no Carthaginian territory in Africa; after this war with Philip she took no land and did not even claim Illyricum. If land was needed, the West offered better and richer ground for expansion. Spain, the Eldorado of the ancient world, had been left on her hands, while the colonization of the Po valley was uncompleted. But in fact the devastated land of Italy itself needed all her attention. There is little evidence to show that the spirit of military imperialism affected Rome’s policy during the first decade of the second century – whatever its influence later. It was too soon after a life-and-death struggle, of which the issue had been uncertain almost to the end, for such a sense of power and superiority to arise which would drive on a people when they most needed rest. The day when Rome could justly be called ‘that old unquestioned pirate of the land’ was not yet. With militarism, commerce may also be rejected as an important cause of the war: the bulk of Roman trade was too small to influence her policy. Trade may have followed the flag, but it hardly pointed the way for it.9
To turn to the other extreme, the motive may have been an altruistic love of the Greeks, which led Rome to adopt what Tenney Frank has called ‘sentimental polities’. The glory of the Greek world which was capturing the imagination of men, as it did again at the Renaissance, may have inspired the Romans to strike a blow in defence of the liberty of Greek states and thus gain for the ‘barbarians’ of the west the respect of the civilized world. A more cynical view, which rejects ‘an over-romantic ardent sympathy for the Greeks’, suggests that such a motive was used by Rome as a mere pretext. ‘The Roman nobility had steeped itself in Hellenic culture, but had no tenderness for Greeks, as the late war had shown plainly enough. … Their philhellenism confined itself to the things of the spirit … they were going to use a philhellenic policy against Philip … because it suited their purpose, not through love of Greece.’10
But between the extremes of militarism and philhellenism a middle course can be traced. Rome may have adopted a policy of defensive, rather than offensive imperialism. With the balance of powers upset in the east and with Philip launched on a career of conquest and trampling on his neighbours’ rights, what guarantee had Rome that he would not turn against Italy when he was sufficiently strong, even if an immediate attack was improbable? May not Rome, through fear of ultimately being forced to fight in self-defence, have tried to forestall Philip? Livy at any rate describes how the consuls tried to stir the people to war by painting in lurid colours the dangers to be expected from Philip’s aggression. The objection to this theory is that the Senate can hardly have had much real anxiety about Philip; it may explain how the Senate drove the people to war, but it hardly explains the Senate’s own policy. To counter this difficulty it has been proposed to substitute Antiochus for Philip in the role of chief villain: it was fear of Antiochus that was the deciding factor with the Senate, who were suddenly converted to a warlike policy by the appeal of Rhodes and Attalus.11 What these ambassadors brought home to the Senate was the danger of Antiochus’ attitude: they were too skilful to emphasize their own grievances against Philip, which would hardly move the Senate, but having got wind of the coalition between Philip and Antiochus they used this information to scare Rome. Antiochus, the conqueror of the east, who had just returned from following the victorious route of Alexander to India, loomed large amid the mist of fears and rumours. What if he combined with Philip and concentrated in Greece as a base of operations against Italy? Now was the moment to intervene in Greece; not to subjugate it, which would have allowed the monarchs to pose as liberators, but to free it and then throw over it the aegis of permanent protection. If the Senate in appealing to the people harped on danger from Philip it was perhaps less because they themselves feared much from that quarter, than because they wished to use Philip’s name as a handle where the more illusive and shadowy Antiochus would fail to touch a practical people. To this appeal to self-protection and self-interest the Senate may have added the claims of Attalus and Greek civilization and even perhaps of Athens. The idea of defensive imperialism, of establishing a protectorate over Greece for the mutual benefit of Rome and Greece (for it is unnecessary to deny any genuine feeling of interest in the welfare of Greece) was probably the determining cause of the Second Macedonian War.12
But it is perhaps a mistake to seek too cut and dried an explanation of the policy of a people who, like the British, proverbially had a genius for muddling through. Rome had sought to avoid interfering with the balance of powers: a policy which though selfish was reasonable and pacific. But circumstances were too strong. The desire to safeguard her future, possibly to punish Philip for his past conduct, possibly also to pose as the patron of the Greeks whose past glories she so admired, all swept her into the vortex of the eastern disturbance. Her actions were not the result of aggressive imperialism, commercial exploitation or territorial covetousness.