Did Marcus Aurelius ever deliberate about his son's succession?

Marcus Aurelius never directly expressed any doubts about Commodus in Meditations but there are passages which some modern historians have interpreted as referring to his son. Frank McLynn, in Marcus Aurelius: Warrior, Philosopher, Emperor, cites one passage of Meditations as indicating that Marcus “feared for the future”. Also, Gregory Hayes, in his introduction to Meditations, states

Though he could hardly have anticipated the century of turmoil that would follow his death, he may have suspected that his son and successor, Commodus, was not the man he hoped.

McLynn does not question Marcus’ devotion to his children, but nor does he view it positively:

Marcus naively believed that a loving environment would ensure that all evil was driven out of the child

Marcus was aware of his son’s less-than-desirable personality, but excused it – as so many fond parents do in similar circumstances – by claiming that he kept bad company and was subject to bad influences, but would soon grow out of it.

Anthony Birley, in Marcus Aurelius: A Biography, doesn’t go quite as far as McLynn in his interpretation of Meditations but nonetheless more than hints that Marcus suspected his son would not follow his wishes when he died. Birley emphasises the fact that Marcus feared his son would not finish the German war when he died, a fear which turned out to be well founded as Commodus returned to Rome upon his father’s death, negotiating peace rather than completing the conquest as his father had wished.

The secondary sources Historia Augusta and Herodian state clearly that Marcus Aurelius had doubts about his son but the reliability of the former in particular is questionable. Ancient historians, understandably, had a very low opinion of Commodus and, in striving to absolve Marcus of blame for producing such a son, may have ‘invented’ or overstated Marcus’ doubts about his offspring. Thus, it is questionable whether we should believe the Historia Augusta on Marcus when it states:

It is said that he foresaw that after his death Commodus would turn out as he actually did, and expressed the wish that his son might die, lest, as he himself said, he should become another Nero, Caligula, or Domitian.

Perhaps Herodian, who was about 10 years old when Marcus died, is a little more reliable. Citing Herodian, who claims to be reporting people close to Marcus, McLynn writes:

To his confidants Marcus admitted that his son was turning out badly and said that he felt the same way about him that Philip of Macedon felt about Alexander the Great – which did not prevent Alexander from going on to immortal glory. Marcus hoped that this would be the case with Commodus, but this was surely one instance of the triumph of hope over expectation.

Whatever the biases of the ancient sources, it is perhaps worth noting that they stop short of saying that Commodus killed his predecessor to guarantee his succession (an accusation that was levelled against Domitian, among others).

So, if Marcus really did have doubts about his son, why did he anoint him his successor?

McLynn argues that Marcus effectively had no choice in naming Commodus as his successor: choosing someone else would most likely have led to a contested succession (i.e. civil war). Further, Commodus was his only surviving son (his twin brother had died age 4) and there was no obvious alternative as neither of Marcus' his sons-in-law were deemed suitable.

The accelerated programme of promotion that Marcus speeded Commodus through on their return from Asia Minor and Greece in late 176 was simply the recognition of necessity, the acceptance that there was no other option.

Commodus was given the title Augustus in 177, having a few months earlier become consul. He was just 15, but the power-sharing was more a formality than a reality. The passage below, in which Herodian – in the manner of Thucydides – constructs a speech for Marcus, illustrates both Marcus’ hope that Commodus could be guided and his doubts that his son was ready to bear the heavy responsibilities of emperor.

Here is my son, whom you brought up, who has just reached the age of adolescence and stands in need of guides through the tempests and storms of life... You who are many must be fathers to him in place of me alone... You must give my son this sort of advice and remind him of what he is hearing now. In this way you will provide yourselves and everyone else with an excellent emperor and you will be showing your gratitude to my memory in the best of all ways.