NS,
He was about when the campaign to abolish slavery was happening in the UK, so while commonplace, the alternative was also well known.
Well known perhaps, but not the Zeitgeist by any means. Again, the carnivore/vegetarian analogy comes to mind - I eat meat and I'm about when others don't. Does that make me immoral?
Anf as the article covers his was not a 'benign' ownership.
Which is a tougher call. Even if the principle “slavery is wrong” had yet to gain traction, cruelty would presumably have been less acceptable. As I understand it, that’s basically the biblical approach – “slavery is fine, but treat them reasonably”.
Further if we say it's not correct to judge actions based on historical zeitgeists, then much of your position on religion being bad is undermined as anything historical was just the zeitgeist.
It’s not quite that. You can “judge” historical actions according to the contemporary morality (ie, whether or not the person was an outlier in his time), but applying contemporary morality to historic behaviours is a mistake.
Of course “bad” is itself a moral judgment. I happen to think that lots of people dying now because of a prohibition on contraception is morally bad, just as by my standards lots of people being slaughtered in religious crusades was morally bad. The difference though is that crusaders were consistent with their moral Zeitgeist whereas (arguably at least) the RCs are not. Whether there are enough catholics who believe a contraception ban to be morally good to constitute a Zeitgeist is another matter though.
Worse…
Worse than what?
…it is surely, correct to extend this from historic positions to cultural zeitgeists.
Not sure of your point here?
There seems a danger here, that in seeking to 'understand' we fall into a trap of going nuclear on morality.
Going nuclear is the position that, as your truths rest on axioms and so do mine, we’re even-stevens. Morality seems to me to be a mix of instinct and reason, but as a practical matter the Zetgeist means we treat outliers – murderers for example – as wrong rather than afford them equal moral status.