Personal horizon is a concept developed by J. J. Valberg in his book Dream, Death and the Self.
In Valberg's view, an undetermined horizon would necessarily be internalised (a.k.a.
This leads to "horizonal" conceptions of consciousness, mind, experience, life, the self, etc.
This corresponds to one's personal horizon being the pre-eminent one, corresponding to a weak version of solipsism (arguably closely related to Hare's egocentric presentism).
Valberg points out the difficulty of reconciling this with his commitment to the view that he shares the world with metaphysical equals; he continues by re-evaluating many well-studied problems in philosophy in light of this notion of the personal horizon.