“Harry Harlow and his colleagues go on torturing their nonhuman primates decade after decade, invariably proving what we all knew in advance: that social creatures can be destroyed by destroying their social ties.”

Letter to The Guardian (1 December 1961), quoted in Bryan Magee, The New Radicalism (1963), p. 102, n.

Speech to the European Republic Committee at the American Club in London (25 October 1978), quoted in The Times (26 October 1978), p. 5
1970s

1990s, The Decline and Fall of the American Empire (1992)

The Voice of the Earth: An Exploration of Ecopsychology (2001)
Context: If we could assume the view of nonhuman nature, what passes for sane behavior in our social affairs might seem madness. But as the prevailing reality principle would have it, nothing could be greater madness than to believe that beast and plant, mountain and river have a "point of view." …minds exist, so we believe, nowhere but in human heads.

University of Havana address (2005)
Context: Here is a conclusion I’ve come to after many years: among all the errors we may have committed, the greatest of them all was that we believed that someone really knew something about socialism, or that someone actually knew how to build socialism. It seemed to be a sure fact, as well-known as the electrical system conceived by those who thought they were experts in electrical systems. Whenever they said: “That’s the formula”, we thought they knew. Just as if someone is a physician. You are not going to debate anemia, or intestinal problems, or any other condition with a physician; nobody argues with the physician. You can think that he is a good doctor or a bad one, you can follow his advice or not, but you won’t argue with him. Which of us would argue with a doctor, or a mathematician, or a historian, or an expert in literature or in any other subject? But we must be idiots if we think, for example, that economy is an exact and eternal science and that it existed since the days of Adam and Eve, and I offer my apologies to the thousands of economists in our country.

Social Deterioration
1980s–1990s, Is Reality Optional? (1993)

1910s, The Progressives, Past and Present (1910)
Context: To my mind the failure resolutely to follow progressive policies is the negation of democracy as well of progress, and spells disaster. But for this very reason I feel concern when progressives act with heedless violence, or go so far and so fast as to invite reaction. The experience of John Brown illustrates the evil of the revolutionary short-cut to ultimate good ends. The liberty of the slave was desirable, but it was not to be brought about by a slave insurrection. The better distribution of property is desirable, but it is not to be brought about by the anarchic form of Socialism which would destroy all private capital and tend to destroy all private wealth. It represents not progress, but retrogression, to propose to destroy capital because the power of unrestrained capital is abused. John Brown rendered a great service to the cause of liberty in the earlier Kansas days; but his notion that the evils of slavery could be cured by a slave insurrection was a delusion analogous to the delusions of those who expect to cure the evils of plutocracy by arousing the baser passions of workingmen against the rich in an endeavor at violent industrial revolution. And, on the other hand, the brutal and shortsighted greed of those who profit by what is wrong in the present system, and the attitude of those who oppose all effort to do away with this wrong, serve in their turn as incitements to such revolution; just as the insolence of the ultra pro-slavery men finally precipitated the violent destruction of slavery.

Ragnar Frisch, " A method of decomposing an empirical series into its cyclical and progressive components http://www.sv.uio.no/econ/om/tall-og-fakta/nobelprisvinnere/ragnar-frisch/published-scientific-work/rf-published-scientific-works/rf1931e.pdf." Journal of the American Statistical Association 26.173A (1931): 73-78.
1930s