[Essay II xxvii 15-18] It all comes down to this...

[Essay II xxvii 15-18] It all comes down to this: For as far as any intelligent Being can repeat the Idea of any past Action with the same consciousness it had of it at first, and with the same consciousness it has of any present Action; so far it is the same personal self. For it is by the consciousness it has of its present Thoughts and Actions, that it is self to it self now, and so will be the same self as far as the same consciousness can extend to Actions past or to come.

[Essay II xxvii 10] One difficulty with Locke's explanation is that the self-conscious awareness he holds to be constituitive of personal identity is, by its very nature, accessible only to the individual self. It follows that third-person judgments of personal identity are systematically liable to error. For the allocation of punishment and reward, human judicatures must rely upon the presumed association of conscious personal identity with that of a living human body.

Although it regards this presumption as defeasible in cases of madness or somnambulism, the civil law rightly focusses upon what it can prove rather than upon what it can only suppose to the contrary.

[Essay II xxvii 19-22] If the security videos convince a jury that this living human body is the one who pointed a gun at the teller, then my protestation that I have no conscious awareness of having the bank is unlikely to prevent my conviction in court, unless I can provide some over-riding evidence of my loss of consciousness.

Locke seems to have been little concerned with the difficulty of proposing an explanation of moral accountability that rests upon a criterion of personal identity that cannot be reliably applied by other observers. The eternal sanctions for obedience to divine law, he firmly believed, will be distributed ultimately by a deity to whom "the secrets of all Hearts" are perfectly accessible: although human courts may err, God will not.

Besides, the most vital role of Locke's account is to link obligation and motivation in the deliberative process that takes place entirely in the first-person mode: it is my own present belief that I will be punished later that disinclines me to misbehave now.

[Essay II xxvii 25-26] The Natural World In addition to the vital awareness of God and morality that guides proper action, practical human knowledge requires some familiarity with the physical world whose features so clearly limit our capacity for happiness.