Lecture 14 – Is Handedness an Intrinsic or Extrinsic Property? (10/13/04)

• Why can't the relationist about space accept an intrinsic account of left vs right – of 'handedness'?
• The 'fitting theory' is the extrinsic account that the relationist needs.
• I'd say it's a plausible account of handedness even if you are absolutist about space.
• We'll describe it by looking at idealised worlds, and how the fitting account explains left-right in that world; the claim is that the left and right mean the same thing for real objects.
  

• Would it change the handedness of anything if we started calling all the left-handed bodies 'right-handed' and v.v.?

• World 1 contains only similar hands:
• (i) form (mentally) the hands into two sets of mutually congruent hands
  
• (ii) call one 'left' and one 'right'   
  

• World 2 contains in addition, smaller hands, fists and glovesof the same size as the original hands, and screws:
• (i) form each kind into two sets of mutually congruent bodies
• (ii) form two collections, each containing one of the sets of each kind – two collections of things that mutually fit together.
• (iii) call on 'left' and one 'right'

• Claim: There's nothing about being 'left' or 'right' that is left out – in this ideal world.

• Claim: Being left or right essentially amounts to nothing more for real objects in our world.

• Kant: Consider a universe in which the only object is a hand:
• it must be either left or right
• there only are internal relations in such a world
• so the difference can't depend on external, extrinsic relations
• the difference must be intrinsic.

• Again, why can't the difference be understood in terms of internal, relations, intrinsic to the hand?

A universe that contains only a hand! (Our universe is probably an enantiomorph – there is no mirror image of our world in the universe – so incongruent to its counterpart, and so Kant's example isn't so fanciful.)

• What is the handedness of a lone hand according to the fitting account? Are there two possible lone hands?
  

• Kant: there must be two possible hands (one left and one right), because if one introduced a body, the hand could only fit on one wrist.

Kant: the lone hand must be either left or right before the body is introduced, because it fits exactly one hand

• How can we understand why there are two possibilities in terms of the fitting account?