Full Idea
If the midpoint on a line between the chair and the window is five feet from the end of the bookcase. This can be true, but if no object occupies that midpoint, then unoccupied points exist
Gist of Idea
We can identify unoccupied points in space, so they must exist
Source
Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Lessons')
Book Reference
Le Poidevin,Robin: 'Travels in Four Dimensions' [OUP 2003], p.40
A Reaction
We can also locate perfect circles (running through fairy rings, or the rings of Saturn), so they must also exist. But then we can also locate the Loch Ness monster. Hm.