Use the existing syntax and create a new relationship (calling them whatever they want, here I use type)
type
- [[I looked up today and saw a blue sky]] - [[type]] -> - [[evidence]]
Side note, since any note can have a relationship, including relationships, you can create interesting layers…
- [[empirical]] - <- [[type]] - [[evidence]] - [[experiment]]
and we can go all sorts of places…
- [[type]] - [[type]] -> - [[relationship]]