Paul thinks that the modelling step is essential for someone to be a “scientist”. Why? Is it because it’s mathematical? Not quite, I’d say. More important is that a model is a system where the meaning of each and every part is made explicit. It makes it possible to communicate what you’ve constructed to others, and for them to understand it in the same way as you, to check the results’ validity.
The step of publishing, and having others check your work, Paul doesn’t feel is necessary. Someone working intelligently and rigorously in their back-garden shed could also count as doing science. I disagree. It is exactly the collective aspect that makes the whole endeavour reliable. And it is the possibility of building on others’ work that makes it productive.
In design and engineering, however, the universe can take the place of peers in reviewing your work. When you build something in the belief that it will work a certain way, that belief has little influence on wheter it will actually work in the way you expected it to. When you’ve made a fundamental error somewhere, or you were unaware of some phenomenon that has an effect on your device or machine, nature will tell you so. It won’t work. Or it will do something you didn’t see coming. Nature will prove you wrong much more unequivocably and persuasively than you peers could have.