Logic Symbols

# Philosophy of Language

## Some Logic Symbols

A fair number of our reading assignments have contained logical symbols.   Here are a few of these with translations.  (Won't display properly unless you have the Symbol font installed.)

 symbol English equivalent interpretation & (sometimes Ù ) and P & Q is true if and only if P is true and Q is true Ú or (inclusive) P Ú Q is true if and only if at least one of P and Q are true ~ (sometimes Ø ) not ~P is true if and only if P is false ® (sometimes É ) if . . . then P ® Q is true if and only if either P is false or Q is true (i.e. if P is true, so is Q; otherwise, if P is false, Q can be either) "x (sometimes ("x), (x) ) for all x "x(x is a tree Ú ~(x is a tree) ) means that everything is either a tree or not a tree (literally:  for all x, either x is a tree or x is not a tree) \$x (sometimes (\$x) ) there is an x such that \$x(x is a tree) says that there is a tree (at least one; could be more than one).  Literally:  there is an x such that x is a tree.

Last update: February 24, 2000.