Here from Cathy Young is a useful survey of the research on academics’ leftist bias and their criticism of the research — what she calls a debate resembling a “wash-rinse-repeat cycle.”
She also looks at whether tenured radicals are succeeding in brainwashing students, concluding that the young “aren’t necessarily dancing to the professors’ political tune.”
Still, although its effects are hard to quantify, narrow campus orthodoxy can safely be assumed to have diminished the life of the mind and the exercise of intelligent citizenship.