We use the phrase
“two books have the same colour”, but we could
perfectly well say: “They can't have
the
same colour, because, after all, this book has
i
ts own colour, and the other book has its own colour
too”. This also would be stating a
grammatical rule, ‒ ‒ ‒ a rule not in accordance with our
ordinary usage. The reason why one should think of these
two different usages at all is this: We compare the case
of sense data with that of physical bodies in which case we make
a distinction between: “this is the same chair that I
saw an hour ago” and “this is not the same chair,
but one exactly
92.
like the
other”. Here it makes sense to say, and it is
an experiential proposition: “A and B
coul
dn't have seen the same chair, for
A was in London and B in
Cambridge; they saw two chairs exactly
alike”. (Here it will be useful if you
consider the different criteria for what we call the
“identity of these
objects”. How do we apply the statements:
“This is the same day … ”,
“This is the same word … ”;
“This is the same occasion … ”,
etc.?)