Ben, why do keep talking about being “measurably” different? Even if the zombie world has to be different physically (on the assumption that there is nothing but physical things), why does the difference have to be measurable? Couldn’t the difference be precisely that the world is made of unconscious stuff instead of conscious stuff? This would be a physical difference but not a measurable difference—all the same mathematical properties.
Ben, why do keep talking about being “measurably” different? Even if the zombie world has to be different physically (on the assumption that there is nothing but physical things), why does the difference have to be measurable? Couldn’t the difference be precisely that the world is made of unconscious stuff instead of conscious stuff? This would be a physical difference but not a measurable difference—all the same mathematical properties.