A bit belatedly, some comments on Robert Ehrenreich's comments on
authenticity the other day: The questions you put revolve around the nub of
authenticity and its ramifications in conservation/restoration.  Australia
ICOMOS sidesteps this problem by asking not 'what is authentic?' but 'what
is culturally significant?'.
The concept of cultural significance as the standard by which you make
decisions on conservation treatments and management programs is very useful
in practice.  There are various criteria of significance in Australian
heritage practice (Australia ICOMOS uses a basic four : historic,
aesthetic, scientific and social), and of course, they are interpreted in
varying degrees of expertise and purpose.  But though there is room for
personal idiosyncracy, this method introduces a systematic process which
establishes some consistency of meaning.
I believe the process can be sensibly applied to artefacts (movable
cultural heritage) too, though I know only one museum which does so, viz
the Powerhouse MUseum in Sydney.
If anyone is interested in following up these ideas with references etc,
email me direct: [log in to unmask]
Cheers - Linda Young