Full Idea
It is not plausible to argue from the fact (if it is one) that it is impossible to verify that two things are exactly equal in length to the conclusion that any two things necessarily differ in length.
Gist of Idea
Inability to measure equality doesn't make all lengths unequal
Source
Sydney Shoemaker (Time Without Change [1969], p.58)
Book Reference
Shoemaker,Sydney: 'Identity, Cause and Mind' [OUP 2003], p.58
A Reaction
A beautifully simple point against anti-realist or verificationist views of the measurement of length. In any case where we can approach perfect precision, but not quite get there, the anti-realist view looks wildly implausible.