More on my Non-Identity With My Living Body

Maximilian J. Nightingale writes:

You laid out this syllogism in a recent post:

My living body will  become a dead body; 
I will never become a dead body;
therefore, I am  not identical to a living body.

It seems to me that if "becoming" means the same thing in both the first and the second premises, then one must say that both Bill and his living body will become a dead body, or that neither will.  It seems that where a living body used to be, a dead body will begin to be.  So also, it seems that where Bill used to be, a dead body will begin to be.

I don't see that the reader has refuted the argument.  Yes, 'becomes' means the same in both premises. 

Now the first premise is true:   It is clear that one day my living body will undergo a radical change and become a dead body: the same body that today is alive will on a future date no longer have the property of being alive but will instead have the property of being dead.  (I am assuming some 'normal' way of dying, as opposed to being instantaneously annihilated in a nuclear blast.  More on this in a moment.)  This is an alterational change: one and the same body will exist at different times in different states, first alive, then dead.  So it is not the case, as the reader claims, that "where a living body used to be, a dead body will begin to be."  That would be an existential change, not an alterational one.  It is not the case that a dead body will begin to be; one and the same body will go from being alive to being dead.

The second premise is also true.  When my body dies, I will cease to exist; but when my body dies it won't cease to exist: it will continue to exist for a while as a corpse.  This is an existential change in me, not an alterational change:  I will cease to exist.  It is not the case that I will change in respect of the property of being alive.

Therefore, I cannot be identical to my living body.  'Will no longer exist' is true of me, but not true of my body. 

"But what if you are annihilated in an explosion so that there is no corpse?"  At this point the argument takes a modal turn.  Even if my body does not continue to exist after I cease to exist, it could;  but it is not possible that I continue to exist after I cease to exist.  So again we have a difference in properties and non-identity.

I have been assuming mortalism, the doctrine that I cease to exist when my body dies.  If mortalism is false, and I exist even after the death of my body, then a fortiori I am not identical to my living body.