Theodore Sturgeon
In 1951, Sturgeon said something that is now known as Sturgeon's Law. He said, "Ninety percent of SF [science fiction] is crud, but then, ninety percent of everything is crud."  At first, this was called Sturgeon's Revelation. Sturgeon has said that "Sturgeon's Law" was originally "Nothing is always absolutely so."  However, the former statement is now widely referred to as Sturgeon's Law. He is also known for his strong support of critical thinking and challenging all normative assumptions: "Ask the next question." He represented this credo by the symbol of a Q with an arrow through it, an example of which he wore around his neck and used as part of his signature in the last 15 years of his life.