Taken to extremes, liberalism eats its own. Exhibit A is the decline of one of the most prestigious and proudly liberal private schools in the city. Ethical Culture Fieldston in Riverdale, founded in 1878 by the son of a rabbi as a model for social justice, racial equality and intellectual freedom, now is convulsed by allegations of anti-Semitism, racial-discrimination lawsuits, quarrels over identity politics, a Diversity, Equity, and Inclusion Department run amok and a unionÂized faculty impervious to criticism. Disgruntled parents are considering ways of extracting their children, angry donors are closing their wallets and distraught teachers are resigning or...