I think there is a confusion between trying to define the line between scientist / non-scientist or coder / Non-coder (Which is difficult to the point of impossible) and the ability for someone who is already a scientist to look at the work of another and decide if it is the work of a scientist

This is why I use the term software literacy. My son is learning to read. He can write is own name and letters, read some words phonetically. All of those things are necessary but not sufficient. But he is not (yet :-) literate. Will it be at ten words ? A hundred? A thousand? Those are silly arbitrary cut offs.

Anyone of us here can tell the difference between literate and illiterate because we have passed through that gateway.

The same goes for scientist or programmer.

But actually trying to write down the exact definition, the point one passes from being able to write a line of executable code and becomes a real programmer? Becomes software literate? Can't do it. Which is also why you can't measure productivity (plus all the reasons Robert Austin has)

I think you are talking about something different. I can practice basic medicine, but no one would call me a doctor. And, no person would accept me calling myself a doctor without some form of external validation that they believed was valid. I can build software, but being a programmer for someone else requires being validated, even minimally, by something external to myself. Even if the validating entity and the person looking to validate me are the same.

But if you are working alone as a hermit, why do titles even matter? Titles are just something someone uses to classify you, and in isolation mean nothing (unless you have split personalities; joking, schizophrenia is a serious subject).