The common meme that the vast majority of people in the antebellum south thought slavery was OK is a great example of this. It doesn't even pass the smell test unless you either don't have a good sense of just how many people were enslaved at that time and place, or you don't think slaves count as people.
That isn't to say that the morals of the people dictating how society worked weren't different at the time, just that getting the phrasing right does matter.
Even that is a somewhat controversial statement - as the author mentioned, historians (or anyone who is interested in and studies history) are apt to bring in nuance. From my understanding from reading the correspondence and journals of people in that era, people in the antebellum South weren't "OK" with the institution of slavery to the same degree. Some thought it was wrong but the most practical option, some thought it was abhorrent, some had their opinions colored by their own fortunes being tied closely to it. Some where abject racists even by the standards of the time.
It was a controversial and nuanced issue at the time... like every other political issue in the public arena.
You negate your own point when the second clause clearly implies that you're still applying the fashionable standards of today.
To demonstrate how the future may be different, you need to apply different standards. The future may well consider today's environmental degradation as simply a necessary step to the glorious future they live in, and be amused at the parochialness of the people of the time who were worried about it. They could use the metaphor of an egg; shortly before the chick hatches, the egg environment is getting pretty nasty, full of waste products that have nowhere to go. The chick can project that death is certainly around the corner if they don't stop growing soon. But it can't stop growing; it must hatch.
(Before you go "But jerf...!" and start trying to tear that metaphor apart, bear in mind I'm writing from the perspective of an already-glorious future here, not claiming it is absolutely something true of the present.)
Another heterodox idea I've considered is that the future may well mock us for our concern over the environment when the real threat was technological tyranny the whole time, except the tyranny probably wouldn't let alone learn that much about the present time.... But the general idea holds; there are plenty of future threats that may turn out in the end to be far more dangerous than the environment and for it to have been a near waste of time in the end to put so much effort into the environment instead of dealing with $THREAT.
To get here, I'm also projecting into the future the subconscious idea that most of us carry that there is something inevitable about the way the future went and that somehow people should have known. A modern example of this is that it's really easy to look at history and say Y2K was overblown and everybody should have known it. But at the time, it was a rational fear, and the reason why it didn't happen is that people worked really, really hard. So in the future, if some other disaster overtakes humanity, I fully expect the future to project back on to us a belief that we should in the here-and-now already know about this threat and have been dealing with what seems to them to be patently obviously a bigger deal than the environment.
In the real here-and-now, where the future is not known, taking good care of the environment is a rational move. But in the future they may really be cursing us for not throwing billions of dollars at friendly AI. Or whoknows what.
This mythos is playing out now in the Brexit debate, where because nothing too bad happened in y2k everyone who makes projections about the likely bad impact of "no deal", including the government's own preparedness staff, are dismissed as "scaremongering".
History becomes propaganda unless you watch it very carefully.
The future may well consider today's environmental degradation as simply a necessary step to the glorious future they live in, and be amused at the parochialness of the people of the time who were worried about it.
I'm doubtful about this outcome, though. If we do significantly degrade the environment, and even if the degradation was arguably necessary, I'm doubtful that "the glorious future" will judge us kindly.
Can you think of cases where current popular sentiment is similarly charitable toward the past? Overall, I think we are quite morally critical of the past, and not very accepting of the tradeoffs that were considered necessary at the time.
Whatever the real outcome is going to be, it is likely that you'd be doubtful of it, though. People's track records on predicting the future weren't all that great even before tech took off on its probably-only-sigmoid-but-still-kinda-exponential-right-now curve.
"Can you think of cases where current popular sentiment is similarly charitable toward the past?"
It would be very hard. I am of the opinion that our current culture is excessively cut off from the past. While not every culture in the world necessary did things like ancestor worship (an extreme of past honoring), our culture is historically very unusual in its outright contempt for the past. And it makes me rather uncomfortable in a lot of ways because I think the 20th century is replete with too many examples of cultures going full on "let's start from a blank page and create the future that should exist!" and failing... several million bodies later.
I find myself wondering how much of it has been the natural severing of experiences due to the aforementioned changing tech (how can I emotionally attach myself to great-great-grandpa's experiences, when he lived his entire life on a farm, hardly moved from his village, and couldn't even imagine the job I currently have, etc. [1]), and how much of it is social engineering by people who essentially don't want you to find out just how many current political ideas have actually already been tried and failed, utterly and horribly. At the same time, in a lot of ways, I think we've changed less than we think, and our contempt for the past may well be one of those things that the future will have contempt for us for. For instance, it's obvious that we believe in many ways that we don't need "privacy" anymore, but it's not hard to see the current furor around social media as the beginning stages of laboriously recreating the need for privacy from scratch. It will be a different idea of privacy than what we had before, but having to tweak the lessons of old is something every generation has to do. How much pain could we have saved ourselves, though, had we tweaked our ideas of privacy instead of throwing them out entirely, only to rediscover them? (And that's before the totality of what the social media giants are doing has really come out and penetrated into the body politic. I suspect social media's troubles have just begun.)
[1]: Not just guessing that, by the way. That's what my family's genealogy has turned up. Seems like they moved maybe once in their lifetime, but certainly my ancestors were not travelers. My grandfather had enough of a hard time understanding my interests; I would appear all but an alien to my great-great-grandfathers.
Pollution and climate change are killing millions. For anyone in the glorious future looking back, I hope they will not be amused at how disturbing that is to us, but instead think, "yeah that was really terrible, thank goodness we got through it".
How emotional are you about the deaths of Roman soldiers in their fight against Carthage?
If you claim anything other than almost total emotional detachment, let me pre-emptively say that I straight up don't believe you, and think you're just saying it for dialectic purposes for the narrow purposes of winning points in this particular discussion, but that in all likelihood it will over a decade before this topic even crosses your mind again, barring perhaps memories of this conversation. Nobody cares. Nobody has the emotional capacity to care that much, because there's too much history, and too much tragedy in it.
No, future humans aren't going to be wringing their hands about whatever horrors we may have suffered. There's a certain amount of evidence that WWII has already passed beyond the cultural event horizon where almost anybody has any deeply felt emotional reaction to reading about it, despite the fact its vets still live among us.
(Also, this is very much exactly the sort of "but jerf!" I was talking about.)
(Also, HN fancies itself rather smart but I gotta say, having discussed this sort of thing now twice in the past couple of days, it does not seem to be populated by people who have any ability to pull themselves out of modern fashions, even hypothetically, even for the duration of a single message. The prospect that people of the future aren't going to look back on us as the Enlightened Ones who had all the answers seems to be something not very many people here can even begin to think. Well... I'll be sure to bring that up with the future when I meet it.)
I doubt we would be judged over nonrenewable usage for advanced at the time tech if it takes say fifteen PHDs to understand how to fabricate a biodegradable future smartphone from say genetically modified algae based nanotech wafers that are subjected to a one hundred and fifteen step process.
But I'm sure you have your reasons for approaching history- and today's issues, for that matter- the way you do.