Cogito is a Latin phrase meaning 'I think' and is famously associated with the French philosopher Rene Descartes. The phrase is often used to summarize Descartes' philosophical argument that one's existence can be deduced from the fact that one is thinking. The crossword solutions for Cogito are ERGO (4 letters), DESCARTES (9 letters), SUM (3 letters), RENE (4 letters), and ITHINK (6 letters). ERGO is a Latin phrase meaning 'THEREFORE' and is often used in conjunction with Cogito. SUM is a Latin phrase meaning 'I am' and is also associated with Descartes' philosophy.