The crucial difference here is that the two “instruments” share the same nature, but they are “measuring” different objects — that is, the hypothetical rationalists do not have access to the same observed evidence about the world. But by virtue of “measuring”, among other things, one another, they are supposed to come into agreement.
The crucial difference here is that the two “instruments” share the same nature, but they are “measuring” different objects — that is, the hypothetical rationalists do not have access to the same observed evidence about the world. But by virtue of “measuring”, among other things, one another, they are supposed to come into agreement.