I suggest that the growing divide between economists on the left and right reflects three factors: epistemic differences (that is, differences in assessing empirical matters), values, and tribalism. I begin by sketching out a simple model to explain the epistemic divide between economists on the left and the right. I also provide some empirical data in support of that model. I will suggest that the deep chasm between economists on the left and the right did not exist as recently as the 1990s. Then I try to explain why the liberalization wave of the 1980s and 1990s first came about, and why it continued until relatively recently. Finally, I discuss some differences in values, and what seems like a growing pattern of tribalism in the economic profession, mirroring broader changes in American society.