A straightforward extension of these arguments to scalar field theories shows that scalars have even parity. That is, P ϕ ϕ ( − − x , t ) P − − 1 = ϕ ϕ ( x , t ) , since P a ( p ) P + = a ( − − p ) This is true even for a complex scalar field. (Details of spinors are dealt with in the article on the Dirac equation, where it is shown that fermions and antifermions have opposite intrinsic parity.)