6.111 All theories that make a proposition of logic appear to have content
are false. One might think, for example, that the words 'true' and 'false'
signified two properties among other properties, and then it would seem to
be a remarkable fact that every proposition possessed one of these
properties. On this theory it seems to be anything but obvious, just as,
for instance, the proposition, 'All roses are either yellow or red', would
not sound obvious even if it were true. Indeed, the logical proposition
acquires all the characteristics of a proposition of natural science and
this is the sure sign that it has been construed wrongly.
- -- Wittgenstein, Ludwig