William Croft (linguist)  William Croft (born November 13, 1956) is an American professor of linguistics at the University of New Mexico, United States. From 1994 to 2005 he was successively research fellow, lecturer, reader and professor in Linguistics at the University of Manchester, UK. He is inventor of and advocate for radical construction grammar, which among other things uses box-diagrams to compare and contrast the grammatical features of different natural languages. He is considered an influential scholar in the fields of functional and cognitive linguistics. William Croft is a member of Save the Redwoods League's Board of Councillors.