I’ve been thinking about the exact same questions recently so let share a few thought. I realize that some of what I am about to say has already been touched upon.
I think that the terms non-interventionist or interventionist and protectionist or free trade are all far too vague to use as a means of describing particular philosophies that already have names. Unless the aims of these positions are stated, then they are more or less useless terms.
For instance, if a country intervenes for the sake of acquiring resources, this might be termed mercantilism, or neo-colonialism, or perhaps imperialism. If this kind of interventionist foreign policy is coupled with free trade, then it may well lead to corporatism or crony capitalism.
If interventionism is proposed for the sake of some “humanitarian” cause, I’m not sure what we would call it, perhaps false philanthropy. This kind of interventionism proposed in tandem with protectionism is close to a model of American liberalism, or in other words social democracy.
Protectionism is also a tricky term, because at first glance it would appear to be a socialist policy, but of course, many American conservatives advocate protectionist policies, such as Pat Buchanan. He’s not exactly a card carrying commie. Also, if you’ve watched the presidential debates then you’ve no doubt heard Duncan Hunter ramble on about how “China is cheating on trade.”
As for the term isolationism, I think a case can be made that every combination of those four terms in one way or another isolates a country, and therefore I don’t know if it’s actually a useful term.
It’s fairly obvious why a country that is non-interventionist and protectionist would be considered isolationist. They’d be like that kid at a party who’s standing alone by himself in a corner.
Interventionism in general can be seen as isolating. Any kind of consistent foreign military adventurism will usually lead to a country being isolated diplomatically. Not mention that levying sanctions against other nations, and preventing your citizens from traveling to another country is rather isolating.
And lastly, many libertarians, who espouse a non-interventionist foreign policy and free trade with others, at one time proudly called themselves isolationists. They of course meant this in a very different way. As Murray Rothbard once explained: “This brand of “isolationism” meant, quite consistently, economic and cultural exchange to the uttermost (free trade, freedom of migration, friendship with all foreign peoples), coupled with the political isolating of the US government from all forms of meddling with and pushing around of the people of other countries.”