There are those who will see it as almost a religious principle that no one can possibly know that a design will work, no matter how good the argument, until it is actually tested.

It's not necessarily a religious principle, although like anything else, it can be made one. It's a simple truth.

There is a non-trivial distinction between believing that a design will work, and believing that a design is highly likely to work. Maintaining the awareness that our maps do not constrain the territory is hard work, but necessary for a rationalist.