Imagine a rock has become dislodged, rolling down a hill just on the outskirts of town. As it's rolling, it picks up an amount of money, which sticks to it. The rock has just enough momentum to roll into a pie shop. The money falls on the counter, a pie is given to the rock, along with the change, and the rock and the pie are then carried out by another customer and placed on a bench.

Did that rock just buy a pie!?

  • Any chance I might be able to persuade you to unpack this a bit further? What might have motivated the concern here?
    – Joseph Weissman
    Sep 27, 2012 at 19:37
  • No, it didn't. It rolled down the hill, got money stuck to it and rolled into a pie shop.
    – mbx-mbx
    Sep 28, 2012 at 9:30
  • Really, really lucky rocks, can buy pies. Or even trigger storms in other parts of the world.
    – user2411
    Sep 28, 2012 at 12:29

1 Answer 1


If rocks did this all the time, in apparent violation of basic laws of motion, then yes, the rocks are buying pies. Otherwise, no, this is just an amusing example that doesn't demonstrate anything except the danger of extrapolating complex properties (like agency) from isolated incidents.

The point of agency is that you gain predictive power by considering the entity in question an agent with internal motivations which it uses to shape its actions. Whether there is something fundamental about agency or whether it's just an emergent property of sufficiently complex physical systems is perhaps debatable, but the rock example doesn't meet the minimum preconditions.


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