Firstly, I should have made it clear that the reference class should only contain worlds which are not clearly inconsistent with ours—we remove the ones where the sun never rose before, for example.
Secondly, some people won’t like how I built the reference class, but I maintain that way has least assumptions. If you want to build the reference class “bit by bit”, as if you are going through each world as if it were an image in a graphics program, adding a pixel at a time, you are actually imposing a very specific “construction algorithm” on the reference class. It is that that would need justifying, whereas simply saying a world has a formal description is claiming almost nothing.
Thirdly, just because a world has a formal description does not mean it behaves in a regular way. The description could describe a world which is a mess. None of this implies an assumption of order.
I will add something more to this.
Firstly, I should have made it clear that the reference class should only contain worlds which are not clearly inconsistent with ours—we remove the ones where the sun never rose before, for example.
Secondly, some people won’t like how I built the reference class, but I maintain that way has least assumptions. If you want to build the reference class “bit by bit”, as if you are going through each world as if it were an image in a graphics program, adding a pixel at a time, you are actually imposing a very specific “construction algorithm” on the reference class. It is that that would need justifying, whereas simply saying a world has a formal description is claiming almost nothing.
Thirdly, just because a world has a formal description does not mean it behaves in a regular way. The description could describe a world which is a mess. None of this implies an assumption of order.