It's a confronting thought, but it seems irrefutable.
There are all sorts of stories we might tell ourselves about ourselves (or about our country, or political grouping), some plausible (in accordance with the facts), some implausible, some delusional. Discard the delusional, set aside the implausible. Fine.
The trouble is, many plausible (and mutually incompatible) narratives remain and there is no way of choosing between them. There is no true version, no 'God's eye view' (unless of course there is a more or less conventional God out there).
So there are no clear answers to questions about whether I am mean or frugal, or whether you are brave or reckless, or whether, morally, anyone is precisely anything.
But it goes further than this. It is not merely a matter of assigning - or not assigning - labels. It goes to the heart of a life's significance and involves the interpretation of complex histories.
To what extent is my life story or my country's history one of inspiring achievements or missed opportunities or a muddle of self-deception; to what extent successful or unsuccessful? It's all in the eye of the beholder.
Two things set limits to this kind of subjectivity: social facts; and the hypothetical logic of values. (Someone with such and such a value system would be inclined to praise or condemn specific behaviours.)
But, in the end - on this analysis, at least - subjectivism holds sway in the realm of values and the vindication we all seek at a fundamental level will never be achieved.