We could start by establishing the argument/parameter distinction in the glossary.  Currently, the word "parameter" does not appear in the glossary, and the definition of "argument" blurs the distinction between the two:

For example, in the following definition of "argument"--

"argument: A value passed to a function or method, assigned to a named local variable in the function body. A function or method may have both positional arguments and keyword arguments in its definition..."

(from http://docs.python.org/dev/glossary.html#term-argument )

the second sentence is actually talking about parameters.