Due 5/6                                                                                                                                                                                                                                

                                                                                                                                                                                                                                                      

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                      

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                      

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                      

                                                                                                                                                                                                                                          

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                          

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          

Philosophy 60                                                                  :    
Homework 5

Instructions:  Prove the following using natural deduction.  Type your name.  Type your answers. Staple or paper clip multiple pages.  If you turn this in by e-mail, type the date and time you sent it on the hardcopy.   Each problem 2 pts.  10 pts total.  

1.  "x(Fx → yFxy), zFz  xyFxy    

2.  xy( Fxy →Fyx), xy¬Fxy  xy¬Fyx  

3.  x¬Fx  ¬xFx  (Since this is a proof of one form of QN, do not use QN in your proof.  All other rules available.)

4.   x(Fx v Ga) → x(Fx v yGy)  

5.  ¬x(Fx & ¬Gx)   x (Fx →Gx)