The '''Law of Non-Contradiction''' can be formulated as follows: Two truths cannot contradict one another.<ref>{{cite web |author=[[Galileo Galilei]] |title=Letter to the Grand Duchess Christina of Tuscany| year=1615, 1998 |publisher= Internet History Sourcebooks Project, Paul Halsall, [The Jesuit] Fordham University [of New York]|url= http://www.fordham.edu/halsall/mod/galileo-tuscany.asp |accessdate=June 10, 2013}}</ref> | The '''Law of Non-Contradiction''' can be formulated as follows: Two truths cannot contradict one another.<ref>{{cite web |author=[[Galileo Galilei]] |title=Letter to the Grand Duchess Christina of Tuscany| year=1615, 1998 |publisher= Internet History Sourcebooks Project, Paul Halsall, [The Jesuit] Fordham University [of New York]|url= http://www.fordham.edu/halsall/mod/galileo-tuscany.asp |accessdate=June 10, 2013}}</ref> |