13.  Personal Identity in Change of Substance.

That this is so, we have some kind of evidence in our very bodies, all whose particles, whilst vitally united to this same thinking conscious self, so that we feel when they are touched, and are affected by, and conscious of good or harm that happens to them, are a part of ourselves; i.e. of our thinking conscious self.  Thus, the limbs of his body are to every one a part of himself; he sympathizes and is concerned for them.  Cut off a hand, and thereby separate it from that consciousness he had of its heat, cold, and other affections, and it is then no longer a part of that which is himself, any more than the remotest part of matter.  Thus, we see the substance whereof personal self consisted at one time may be varied at another, without the change of personal identity; there being no question about the same person, though the limbs which but now were a part of it, be cut off.

14.  Personality in Change of Substance.

But the question is, Whether if the same substance which thinks be changed, it can be the same person; or, remaining the same, it can be different persons?

And to this I answer:  First, This can be no question at all to those who place thought in a purely material animal constitution, void of an immaterial substance.  For, whether their supposition be true or no, it is plain they conceive personal identity preserved in something else than identity of substance; as animal identity is preserved in identity of life, and not of substance.  And therefore those who place thinking in an immaterial substance only, before they can come to deal with these men, must show why personal identity cannot be preserved in the change of immaterial substances, or variety of particular immaterial substances, as well as animal identity is preserved in the change of material substances, or variety of particular bodies:  unless they will say, it is one immaterial spirit that makes the same life in brutes, as it is one immaterial spirit that makes the same person in men; which the Cartesians at least will not admit, for fear of making brutes thinking things too.

15.  Whether in Change of thinking Substances there can be one Person.

But next, as to the first part of the question, Whether, if the same thinking substance (supposing immaterial substances only to think) be changed, it can be the same person?  I answer, that cannot be resolved but by those who know there can what kind of substances they are that do think; and whether the consciousness of past actions can be transferred from one thinking substance to another.  I grant were the same consciousness the same individual action it could not:  but it being a present representation of a past action, why it may not be possible, that that may be represented to the mind to have been which really never was, will remain to be shown.  And therefore how far the consciousness of past actions is annexed to any individual