Robert Louis Stevenson beautifully describes the ever-shifting terrain of politics:

History is much decried; it is a tissue of errors, we are told, no doubt correctly; and rival historians expose each other’s blunders with gratification. Yet the worst historian has a clearer view of the period he studies than the best of us can hope to form of that in which we live. The obscurest epoch is today; and that for a thousand reasons of inchoate tendency, conflicting report, and sheer mass and multiplicity of experience; but chiefly, perhaps, by reason of an insidious shifting of landmarks. Parties and ideas continually move, but not by measurable marches on a stable course; the political soil itself steals forth by imperceptible degrees, like a traveling glacier, carrying on its bosom not only political parties but their flag posts and cantonments; so that what appears to be an eternal city founded on hills is but a flying island of Laputa.   [From “The Day After To-morrow”]

I love the flag post on the glacier metaphor.

On the left, people have shifted from marching in support of “free speech” to opposing free speech. They went from advocating a colorblind society to the view that colorblind policies are racist. Many of the right went from outrage over “defund the police” to advocating defunding the tax police and the FBI. The Democrats once opposed abortion more than the Republicans, now the reverse is true. Republicans went from praising Houston’s lack of zoning to the being the biggest NIMBYs on the block. Attitudes toward Russia flip flopped after the 2016 election. Free trade, immigration, almost any issue you could cite has no fixed political home.

To channel Robin Hanson; in politics, X is never about X. The free speech movement of the 1960s was not about free speech; it was a demand that we tolerate left wing ideas. The civil rights movement of the 1960s was not about civil rights; it was about improving the condition of blacks in America. On both the left and the right, defunding movements are aimed at government entities that seem to persecute their voters. Republicans supported abortion rights when they saw the opposition as composed of Catholics trying to boss them around. Votes on legislation affecting trade, immigration, zoning, etc., hinge on how the policies are seen as affecting the political coalition that currently votes for their party.

Matt Yglesias recently linked to this graph:

Note that as recently as 1996, blue states like Colorado and Virginia voted for a Republican, while deep red states like Louisiana, Tennessee and West Virginia voted Democratic.  Go back further and the changes are far greater.  And yet our pundits talk about politics as if “Democratic” and “Republican” were a fixed type, unchanging from year to year.  There is a subtle pressure to join one of the two tribes.

One way to think about this is to notice that 90% of American voters are mostly unprincipled.  I don’t mean that as a pejorative, merely a description of their approach to politics.  Presumably they would defend their approach as being pragmatic, not locked into a rigid ideology.  This means that the other 10% of us end up wandering around, with no fixed tribe to call our home.  And it can be quite uncomfortable to be a fixed post stuck deep in the bedrock as a glacier grinds past.  Especially when the 90% believe that they are the ones with consistent views.

PS.  Immediately after the quotation above, Stevenson had this to say about a gradual change in the meaning of “liberalism” during the late 1800s:

It is for this reason particular that we are all becoming Socialists without knowing it; by which I would not in the least refer to the acute case of Mr. Hyndman and his horn blowing supporters, sounding their trumps of a Sunday within the walls of our individualist Jericho, but to the stealthy change that has come over the spirit of Englishmen and English legislation. A little while ago, and we were still for liberty; “Crowd a few more thousands on the bench of Government,” we seemed to cry; “keep her lead direct on liberty, and we cannot help but come to port.” This is over; laisser-faire declines in favor; our legislation grows authoritative, rows philanthropical, bristles with new duties and new penalties, and casts a spawn of inspectors, who now begin, notebook in hand, to darken the face of England. It may be right or wrong, we are not trying that; but one thing it is beyond doubt: it is Socialism in action, and the strange thing is that we scarcely know it.