### A Standard Of Measure

by Stephen McAndrew

There is one thing of which one can say neither that it is one metre long, nor that it is not one metre long, and that is the standard metre in Paris. – Ludwig Wittgenstein (1)

When scientists decided to come up with the metric system, they needed a standard of measure.  A metre stick stored in Paris, made of platinum, was chosen as the standard against which all metres were to be measured.  Platinum was chosen because it would not vary or decay.  However, today the platinum metre has been superseded by laser light for the same reason. (2)

A standard of measure needs an objective source that can be accessed so as to verify the accuracy of a particular measure.  That source must be constant and unchanging.  Obviously, if the standard metre were constantly changing measurements would be unreliable.  If measurements could not be relied on, they could not be used in science, commerce, or everyday life and the metre as a standard of measure would be abandoned.

The metre stick in Paris, therefore, holds a special place in the measurement system.  It is the standard by which all other metres are put against to see if they measure up.  Ludwig Wittgenstein, the celebrated twentieth century Austrian philosopher, wrote that the metre stick in Paris was neither one metre long, nor not one metre long.

What does this mean?  Wittgenstein is often enigmatic, but he seems to be saying that the standard metre in Paris is not a metre long because it can’t be measured against itself to see if it is one metre long.  To see if it is one metre long, we would need another standard metre to measure the Paris standard metre against.  Then we would need another standard metre to measure that metre against, and so on into infinity.  So, it makes sense to have a starting point, a standard metre that is sui generis, that it to say, it can’t be measured against anything else…