A haecceity is a property H of x such that: (i) H is essential to x; (ii) nothing distinct from x exemplifies H in the actual world; (iii) nothing distinct from x exemplifies H in any metaphysically possible world.Vallicella takes it for granted there cannot be haecceities. They are 'creatures of darkness'. But assuming there aren't, the problem is that if God is omniscient (i.e. knows everything that is, has been and will be) then he must have known which individuals he was going to create when he created the world. (For example, he must have known he was going to create Socrates). This cannot be explained without presuming haecceities (per Vallicella). Since there are no such things, God is not omniscient.
I reply: if we can make an identifying reference for items that exist now ('this baby here'), and items that existed in the past ('Isaiah'), why can't we make identifying references in the future? Isn't the 'he' below such a future identifying reference? Does it require a haecceity existing when Isaiah made the prophesy? Why? Why can't the reference reach over the future centuries in order to identify the yet-to-be-born Jesus?
For to us a child is born,
to us a son is given,
and the government will be on his shoulders.
And he will be called
Prince of Peace. [Isaiah 9:6]