Hypothetical propositions are used pervasively in everyday
reasoning, and they can be expressed in a variety of nonstandard
forms. In the remainder of this section, we look at some of
the more common nonstandard forms.
"p only if q"
"p if and only if q"
"p unless q"
"Whenever p, q"
"Without p, then q"
Of course, there are other nonstandard ways of expressing
disjunctive and hypothetical propositions. Our language is far
too rich and subtle for us to capture every possibility in a
small set of rules. But what we outline here encompasses a great many statements occurring in everyday speech.