The voiced alveolar tap or flap is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents a dental, alveolar, or postalveolar tap or flap is ⟨ɾ⟩. The terms tap and flap are often used interchangeably. Peter Ladefoged proposed the distinction that a tap strikes its point of contact directly, as a very brief stop, and a flap strikes the point of contact tangentially: "Flaps are most typically made by retracting the tongue tip behind the alveolar ridge and moving it forward so that it strikes the ridge in passing." That distinction...

The Weather Underground was a far-left militant organization first active in 1969, founded on the Ann Arbor campus of the University of Michigan. Originally known as the Weathermen, the group was organized as a faction of Students for a Democratic Society (SDS) national leadership. Officially known as the Weather Underground Organization (WUO) beginning in 1970, the group's express political goal was to create a revolutionary party to overthrow the United States government, which WUO believed to be imperialist. The FBI described the WUO as a domestic terrorist group, with revolutionary positions...

The Better Angels of Our Nature: Why Violence Has Declined is a 2011 book by Steven Pinker, in which the author argues that violence in the world has declined both in the long run and in the short run and suggests explanations as to why this has occurred. The book uses data simply documenting declining violence across time and geography. This paints a picture of massive declines in the violence of all forms, from war, to improved treatment of children. He highlights the role of nation-state monopolies on force, of commerce (making other people become more valuable alive than dead), of increased...