“I don’t think. I know.” We’ve all heard this, and most of us have probably uttered this phrase ourselves a time or two. But when you think about it (no pun intended), this phrase represents a misuse of language. It sets up a contrast between thinking and knowing, wherein “thinking” denotes uncertainty and “knowing” denotes certainty. While this may reflect a popular connotation of these words, denotatively speaking, neither has anything to do with certainty.
“Think” is a description of what the mind does. It describes the mind’s activity. Knowledge is “justified, true belief.” Certainty is not part of the definition, and thus certainty is not required for knowledge. To know something only requires that we have adequate justification.
Thinking to Believe 