This came up in a discussion I had with Huenemann earlier today:
You’ve all heard the expression – ‘How many angels can dance on the head of a pin?’ – used to disparage the apparent waste of good brain-power in trying to sort out pointless problems.
a) What is the origin of this question? I had long thought that no medieval philosopher really asked it, but that the question was made up later in order to lampoon those ‘silly’ Scholastics. After doing a quick bit of research, I think I have identified the origin of the question: It seems it was first asked in a satirical book called ‘Memoirs of the Extraordinary Life’, a book written under the pseudonym ‘Martinus Scriblerus’ (Alexander Pope, Johathan Swift, and others collaborated on the work). They were making fun of Scholastic philosophers, and in particular Thomas Aquinas.
Aquinas did produce a very sustained ‘angelology’, still thought by many to be the most complete investigation of angels. He used both scriptural and non-scriptural (Aristotle) sources to try to sort things out, determining that angels were immaterial intellects of great power who can assume bodies and who learn through a kind of direct communion with the mind of God. In fact, the way that Plato describes humans (learning through recollection, knowledge of the Forms) is pretty close to what Aquinas says about angels.
But, as best as I can tell, it is not the case that Aquinas or any other medieval thinker asked this particular question regarding angels dancing on the head of a pin (though they did ask related questions).
b) That said, now that the question has been asked, it may turn out to be a decent question. Aquinas does think that angels have locomotive powers (the ability to move from one place to another), and he debated whether or not they have to pass between all intermediate points when moving from A to B. He thought they need not move through all points when traveling between two points but instead can ‘jump’ from one location to another in a non-continuous way (thus anticipating similar suggestions in contemporary string theory). Read here.
And he wondered whether several angels could be in the same place at the same time. In the end, he did not think that many angels could be in the same place at once. Read here.
Now, no matter what we might think about Aquinas or angels, the issue raises some interesting questions. Huenemann had recently read a book on early modern physiology that asked related questions: What is the relationship between matter and space? Why does matter occupy space, and why can’t more than one object occupy the same space? What is the relationship between matter, mass, and location? Are mass and location essential qualities of space (that it is the ‘form’ of matter to have those attributes)?