A 'function' can't call itself (by name or by any other method), but since 'functions' can call each other, and can make each other to call each other, recursio

A 'function' can't call itself (by name or by any other method), but since 'functions' can call each other, and can make each other to call each other, recursion is mostly trivial. You try it, then you'll get a working recursion one way or another. (Lambda calculus don't operate on functions, but on expressions/lambda terms.)