In the field of political science, social engineering is a mainly pejorative term used to describe the intended effects of authoritarian systems of government. The implication is that some governments, or powerful private groupings, are intending to change or "engineer" the citizenry, for example, by the use of propaganda, through the manipulation of culture, or though the legal system. The discussion of the possibilities for such manipulation became quite active following World War II:

..."I think the subject which will be of most importance politically is mass psychology.... Its importance has been enormously increased by the growth of modern methods of propaganda. Of these the most influential is what is called 'education.' Religion plays a part, though a diminishing one; the press, the cinema, and the radio play an increasing part.... It may be hoped that in time anybody will be able to persuade anybody of anything if he can catch the patient young and is provided by the State with money and equipment."

"...The subject will make great strides when it is taken up by scientists under a scientific dictatorship.... The social psychologists of the future will have a number of classes of school children on whom they will try different methods of producing an unshakable conviction that snow is black. Various results will soon be arrived at. First, that the influence of home is obstructive. Second, that not much can be done unless indoctrination begins before the age of ten. Third, that verses set to music and repeatedly intoned are very effective. Fourth, that the opinion that snow is white must be held to show a morbid taste for eccentricity. But I anticipate. It is for future scientists to make these maxims precise and discover exactly how much it costs per head to make children believe that snow is black, and how much less it would cost to make them believe it is dark gray."

"...Although this science will be diligently studied, it will be rigidly confined to the governing class. The populace will not be allowed to know how its convictions were generated. When the technique has been perfected, every government that has been in charge of education for a generation will be able to control its subjects securely without the need of armies or policemen."

--Bertrand Russell, The Impact of Science on Society, 1951

Laws and tax policies can influence behavior, and progressive politics often promote socially influential policies. Often the judgment about whether a policy is "progressive" or not depends on whether that policy aids or hinders the thinker -- one man's leader is another man's tyrant. The coercion remains the same.

A general meaning is any attempt by a government to alter society. Whether a government is supporting or altering a society depends upon what is the purpose of government, although few governments practice social engineering on satisfactory citizens.