Bryan Caplan writes about a libertarian penumbra, which includes ideas that aren’t explicitly libertarian, but are nonetheless disproportionately embraced by libertarians:
Libertarians have many beliefs in common that have little to do with the consequences of liberty. They’re just part of our vibrant, iconoclastic intellectual subculture.
Penumbra (a word I didn’t know the meaning of) when used in this sense, is even more present in more mainstream political movements, which are defined less by coherent though frameworks, and more by coalitions of groups with compatible but independent objectives. It’s hard–not impossible–to tie opposition to abortion, tax cuts, and gun rights together a common theory. But people who believe strongly in one of these are more likely to support the other two. The mechanism for this, I think, is that strongly holding one of these views leads you to vote Republican. This in turn exposes you disproportionately to other members of the Republican coalition, who will present you with a disproportionate number of arguments supporting their stance. The same mechanism applies to liberals, libertarians, and any group of like-minded thinkers. In most cases, people who hold certain views are more likely to listen to people who share their views, even when the ideas being presented are entirely unrelated to the shared views.
Which [libertarian penumbra ideas] are most subject to abuse? Are there any that make you cringe?
My answer: all of them.