There are at least three definitions of creativity in circulation. One, you are the first person in history to have that idea. (rare, but I've seen it) Two, you came up with an idea that was new to you. (most common) Three, you have a new idea that gains social acceptance. (Teresa Amabile argues for this one in Creativity in Context (1996))

I wasn't referring to that last definition, but to the view that intellectual environment is so important for supporting the exploration of ideas that true solitary creativity doesn't happen. For books arguing this view, try Robert Weisberg, Dean Keith Simonton, and Keith Sawyer. Study specifically on creativity in lab research was done by Kevin Dunbar, who also found the social aspect essential.