"I don't consider myself to be that radical a thinker"

In this quote, Steven Pinker is revealing his opinion that he does not consider himself to be an especially extreme thinker. This could indicate that he does not believe of himself as somebody who has particularly severe or non-traditional ideas, or that he does not believe of himself as someone who is willing to take risks or challenge the status quo. It could also imply that he does not believe of himself as somebody who is particularly ingenious or imaginative in his thinking. In any case, it appears that Pinker does not consider himself to be a particularly extreme thinker, and instead chooses to take a more moderate technique to his thinking.