martedì 28 giugno 2016


  • I’m not that happy with framing our analysis choices here as surface analogies” versus “inside views.” More useful, I think, to see this as a choice of abstractions.  An abstraction neglects some details to emphasize others.  While random abstractions are useless, we have a rich library of a useful abstractions, tied to specific useful insights
  • For example, consider the oldest known tool, the hammer To understand how well an ordinary hammer performs its main function, we can abstract from details of shape and materials.  To calculate the kinetics energy it delivers, we need only look at its length, head mass, and recoil energy percentage (given by its bending strength).  To check that it can be held comfortably, we need the handle’s radius, surface coefficient of friction, and shock absorption ability.  To estimate error rates we need only consider its length and head diameter.
  • For other purposes, we can use other abstractions:

  • To see that it is not a good thing to throw at people, we can note it is heavy, hard, and sharp.
  • To see that it is not a good thing to hold high in a lightning storm, we can note it is long and conducts electricity.
  • To evaluate the cost to carry it around in a tool kit, we consider its volume and mass.
  • To judge its suitability as decorative wall art, we consider its texture and color balance.
  • To predict who will hold it when, we consider who owns it, and who they know.
  • To understand its symbolic meaning in a story, we use a library of common hammer symbolisms.
  • To understand its early place in human history, we consider its easy availability and frequent gains from smashing open shells.
  • To predict when it is displaced by powered hammers, we can focus on the cost, human energy required, and weight of the two tools.
  • To understand its value and cost in our economy, we can focus on its market price and quantity.
  • [I’m sure we could extend this list.]
  • Whether something is “similar” to a hammer depends on whether it has similar relevant features. Comparing a hammer to a mask based on their having similar texture and color balance is mere “surface analogies” for the purpose of calculating the cost to carry it around, but is a “deep inside” analysis for the purpose of judging its suitability as wall art