If you are an internalist pursuing rigorous deducibility and testability, you try to evaluate what others say about properties of the language faculty on the basis of experiments that you can conduct in your single-reseacher-informant experiment, where you test definite predictions that you can deduce in part from the hypotheses under discussion against your own intuitions. If what you read or listen to does not provide an explicit formulation of the proposed universal hypothesis/ses or an explicit means to test its/their empirical consequences, you do not what to do. One of the aims of the methodology proposed in my CUP book for language faculty science as an exact science is to make a life easier for those who are internalists pursuing rigorous deducibility and testability.

(I have not come up with a tern that refers to someone who is committed to the Guess-Compute-Compare method. If I had a term for that, I could state the content of the if clause above as, "If you are both an internalist and a xxxist.")