It does not question other peoples intelligence, but rather their knowledge of programming language paradigms. You can program functionally in any language by

It does not question other peoples intelligence, but rather their knowledge of programming language paradigms. You can program functionally in any language by eschewing side-effects whenever you can. Only that in some languages it is way easier to program functionally than others (ML, Scheme, Common Lisp, Erlang) and in some it is even forced (Haskell). The "idiot" here is the one that can't see or understand that it is easier to program functionally in functional languages and that it leads to better programs by doing so. To see this, you need knowledge of functional programming. And sadly, many people do not understand its finer points because they have not spent time writing non-trivial programs in functional languages. If you know nothing about FP on the other hand, you could be lead into the concept of Dependency Injection, Design Patterns and whatnot, because your world is shaped around a statical subtyping system (In the case of Java). These concepts are not bad at all: they help Java programmers write better code (for most part) with fewer errors.