In the 'the selfish gene' Dawkins writes (page 109): "The reason lions do not hunt lions is that it would not be an ESS (evolutionary stable situation) for them to do so. A cannibal strategy would be unstable for the same reason as the hawk strategy in the earlier example."
To quickly summarise this: we consider an interaction between two animals where one possibly stands something to gain. Dawkins then defines 'hawk' behaviour as attacking behaviour, whilst 'dove' is described as peaceful and retreating behaviour. He then argues that a population of purely hawk or purely dove is unstable, since in either of the situations the other kind of behaviour is more favourable. As it turns out, the stable situation is 7:5 for hawk:dove.
Turning to cannibalism, we can regard the hawk behaviour as 'engaging in cannibalism' and dove to be the refraining party. Why, then, don't we see similar behaviour when considering cannibalism, i.e. why don't we see a reasonably large amount of lions engaging in cannibalism whilst the others refrain from it? If I am not mistaken we see in fact the situation more closely described by completely dove? Any insights are appreciated!