If you create a model of the world that uses a fundament of objectivity, you reliably conclude that consciousness doesn't exist. Consciousness does exist, which means the philosophy is empirically unsound.
This amuses me greatly. Though of course it shouldn't. Naturally Empiricists would betray empiricism. Why should it ever be otherwise?
By contrast, a model using the subjective as primary has no trouble re-deriving physics from solipsism. The objective world is merely the thoughts that are shared as opposed to the thoughts which are private.
If the thoughts were not logically consistent across minds, they would not be shared, as a matter of logical necessity. We do in fact observe other minds (regardless of how reliable that observation is) and therefore absent strong evidence to the contrary, should assume some thoughts are shared.
Since thoughts are shared and logically consistent, they must be consistent across observers - in other words, to reiterate the properties of objectivity.
To see this another way, notice how the shared-thoughts paradigm causes Newton's Third Law. If I perceive your thought touching my thought, likewise you must perceive my thought touching yours. (Kindly leave the gutter thoughts to adolescents. They have that covered.) Else there's a logical inconsistency, and the thoughts are not in fact shared, and you'll be able to observe them rapidly diverging even if they appear coincident at first glance.
Perhaps one form of death is losing track of the shared thoughts. If you forget all other minds, it is like they don't exist, and likewise, to them, like you don't exist. You may still exist, but it doesn't matter.