But I didn't know until today that Heinlein was a Libertarian. I suppose I could have figured it out from the anarchist flavor of some of his writings.
In the late 1930s Heinlein indulged in both leftist and isolationist politics. Later he became an ardent anti-communist. In 1958, in response to what he saw as a liberal effort to weaken America's military, he set aside his book in progress and wrote "Starship Troopers", in which he created a future world in which service was a requirement for citizenship.
After that he finished the work he had set aside, which was SISL. If you haven't read SISL, let me just say that it is in my top 100 recommended books. It is from this book that the work "grok" entered the English language.
Heinlein's political beliefs kept moving toward libertarianism. He supported Barry Goldwater in 1964, and in 1966 he published The Moon Is a Harsh Mistress, a tale of penal colonists on the Moon revolting against their Earthly masters. According to Dinerman, this book is near the top of Libertarian reading lists because of a speech by a professor in the book, delivered to the rebels' constitutional convention: ". . . like fire and fusion, government is a dangerous servant and a terrible master. You now have your freedom--if you can keep it. But do remember that you can lose this freedom more quickly to yourselves than to any other tyrant."
The speech continues: "The power to tax, once conceded, has no limits; it contains until it destroys. I was not joking when I told them to dig into their own pouches. It may not be possible to do away with government--sometimes I think that it is an inescapable disease of human beings. But it may be possible to keep it small and starved and inoffensive--and can you think of a better way than by requiring the governors themselves to pay the costs of their antisocial hobby." As they say on the Moon, "TANSTAAFL!": "There Ain't No Such Thing as a Free Lunch!"
Here's the link to Dinerman's full article: