Earlier quoted context omitted.
It is ironic how that is a mirror image of fascist beliefs about military virtue. They wanted to give power to veterans so that wars could be started and won! They wanted to suppress the influence of weak willed peacniks. It is ironic that this could be reversed to imply that rationality means peace. Heinlein had some pretty fascist ideas, and books like starship troopers project that in a comfortable form. It is eas…
Heinlein's point was that one's vote is a huge responsibility, and that privilege must be earned: by demonstrably placing the needs of one's country above individual wellbeing. Thus only military veterans could participate in governance. Militarism doesn't automatically equate to fascism. There are further ideas in this: that, having experienced a war, a (typical) person would never again allow such a thing to happen…
Except for the fact that its pandering to the survivors fallacy. Of course, the ones who don't want to fight wars won't be around - they'll have been dead. The ones who survived war, are more likely to want more war - especially when they emerge as the victor nation. Just look at how blood-thirsty the 5-eyes nations are, currently: none of them have truly 'lost wars' (i.e. fought on their own territory), only troops. Yet, here today, don't ask your average Aussie to ever criticise their nations war-making; they'll think you need psychiatric help for just questioning the Australian Defence Forces' heinous crimes...