'If' versus 'Iff'


Could you please tell me if I can use Iff as freely as I can use If. I think Iff means ‘If and only iff’


Hi Tom,

Sorry, never heard of it!


I remember iff from my university time. It is widely used in mathematics (in particular, in logic) - yes, for if and only if
So, it’s more strict than just 'if.

In mathematics it is equvelent to necessary and suffucient conditions. When you prove conditional (theorem) statement ‘in both sides’ (directly and vice versa).

In logics
A iff B means that A and B both true (simultaneously) OR A and B both false (simultaneously)

Too erudite for general usage, Tom. It is just a mathematical acronym.

They also use iff in philosophy and linguistics. The average person walking down the street doesn’t know what it means.