The housing crisis

On his new Strictly website Bill criticises Peter Van Inwagen's denial of composite objects.  Bill asks,

Why does van Inwagen think that a house of blocks is an object radically different from the blocks that compose it? And why does he think that if there are, say, 1000 blocks, then in the place where the house is, there are 1001 objects? Not only do I find these notions repugnant to my philosophical sense, I suspect that it is their extremism that motivates van Inwagen to recoil from them and embrace something equally absurd, namely, that there are no such things as houses of blocks or inanimate concrete partite entities generally.

Bill is not so keen on PVI's claim that the house is an object radically different from the blocks.  But both agree that it's untenable to say that the house is a 1001th object, in addition, as it were, to the blocks. PVI resolves the problem by denying the house's objecthood; Bill by equivocation on 'exists', though he does not quite spell out how his distinction between 'dependent' and 'independent' existence does the job.

Bill says,

First off, it [the house] is not identical to any one of its proper parts. Second, it is not identical to the mereological sum of its parts: the parts exist whether or not the house exists. From this it follows that there is a sense in which the house is 'something more' than its parts. But surely it is not an object "radically different" from, or numerically additional to, its proper parts. If there is a house of 1000 blocks in a place, there are not 1001 objects or entities in that place. After all, the house is composed of the blocks, and of nothing else.

One problem we face is that the term 'the parts' conveys no information as to their configuration.  So the parts can exist stacked on a pallet, say, without the house existing.  And the stack of blocks would seem to be 'radically different' from the house.  Moreover, most configurations of the blocks, if indeed they composed what we would regard as an object rather than a mere sum, would be radically different from the house.  It's only when the blocks are arranged housewise that the question arises whether they are no longer radically different from the house.  I'm inclined to agree with Bill that the terms 'the house' and 'the blocks arranged housewise' are co-referring.  After all, it makes sense to say,

Bob built/lived in/dismantled the house/the blocks arranged housewise.

But is the house 'numerically additional to' the blocks?  If we have 1000 blocks forming a house does the house count as a 1001th object?  Bill says No, but this seems to me to run counter to our ordinary use of the term 'object'.  When Bob assembles his blocks housewise he brings into existence a new object, namely the house.  The number of house objects in the world increases by one, and the number of block objects remains unchanged.  We might ask, How many triangles are in the figure below?

The answer that's usually expected is five, not four.  It's hard to avoid the conclusion that artifacts are systems of 'overlapping' objects.  A production line might take simple parts, build them into sub-assemblies, combine these into larger assemblies, and then compose these assemblies into the finished artifact.  At every step we have tangible objects, and objects can be parts of other objects.  Whether it makes sense to count all these objects rather depends on what we are counting them for.   To find the mass of the final artifact we would add the masses of just the simple parts.  To include the masses of the sub-assemblies would be a 'double-counting'.  But if we wanted to make an annotated diagram showing the assembly process we would probably want to number both the simple parts and the sub-assemblies.  So my conclusion is that Bill's question,  Does the house exist in addition to the blocks? is rather ill-posed.  We have to get clearer as to what we mean by 'in addition to'.