Here is one of the most spectacular shifts in public opinion in our lifetime.
What explains this?
Don’t ask the psychologist and social scientists who study political opinion. They don’t know.
One family of influential theories says that our political opinions are “motivated” by certain deep-seated emotional needs. According to one version, the “system justification theory” of Jon Jost, variation in the need to justify the status quo distribution of goods and power in society determines whether one has a broadly liberal or conservative worldview. In other versions of the needs-based theory, our opinions are said to be fixed by the degree to which we are or are not dominated by a need to preserve comforting illusions, or, alternatively, the need to manage uncertainty and fear.
A related line of inquiry posits that variations in political opinion arise from ingrained differences in personality and moral sensibility. Jonathan Haidt’s “moral foundations theory” is probably the best-known. Variation on the six foundations of the moral sense explains whether you have a liberal, conservative, or libertarian cast of mind. All these theories imply that our “values” and corresponding political views reflect idiosyncrasies of personality more than material interests. Indeed, the current consensus view among political psychologists and public-opinion researchers is that, contrary to older tradition in economics and political science, self-interest explains very little about our political alignments and commitments.
What is often overlooked is that both old-fashioned self-interest theories and new-fangled personality-based theories of political opinion are pretty much useless in accounting for the sort of sea change in opinion captured by the chart above. Was there a wild change in people’s interests between 1996 and now? No. Did the distribution of personality types in the American population undergo a rapid transformation. No. It’s a lot simpler than that. People changed their minds.