It's a question of which causes are the more important ones. For example, the rise in Varroa mites is probably a secondary effect caused by insecticides, but which insecticides? Colony collapse disorder is a thing, but nobody is 100% sure what is causing it yet.
So the scientists say "we don't know". Which is true... but it is very clear who is causing it. It's us. Humans. It doesn't really matter if it's the chemicals that we make in the millions of tonnes specifically to kill insects, or the ones we make in the billions of tonnes to do other things which happen to kill insects, or the ones we accidentally create as byproducts which happen to kill insects, or whether it's because we're destroying the wilderness that they need to survive, or it's something we don't know yet.
E.g. vultures in India are doing very badly. It's humans, but it's by accident.
Some Indian religions practice "air burial". They let vultures eat the bodies.
Dying people often feel unwell. They take painkillers. Paracetamol is cheap. India is poor. People take a lot of paracetamol and then some of them die.
Paracetamol is toxic to vultures.
It's still humans, but it's indirect and accidental, but it's 100% our fault.
It is a fallacy to say scientists don't know what is causing it but they/we know its humans for sure! Huh? What?! That don't make no damn sense. You got to know something before you know it, you know?
In your vulture example we know why the vultures died so we can tie it to a human behavior. We don't know why the bees die or what the deal is with the mites so we can't tie it to human behavior. You are still making a leap of faith, no matter how logical or likely it seems or in fact is.
While I agree that it's probably likely that humans are the cause I disagree with you outright stating humans are. I can still see some non-human probable causes like an undiscovered disease in or multiple species.
"OK, so, we have killed off 96% of all wild mammals, destroyed most of the wilderness on land and in the sea, caused runaway eutrophication in freshwater and massive dead zones in the sea, doubled the amount of CO₂ in the atmosphere, along with vast quantities of other damage, destruction, and pollution...
"But there is a small change that a new disease that is killing off lots of bees is just a coincidence, so we must not rule it out."
That's not at all what I'm saying and I'm not sure how you could interpret it like that. To be able to handle this crisis the start point is to determine what is the cause. If you don't know the cause there is no hope fixing it. Just throwing your hands up and saying Humans are the cause is useless, well unless you want to "solve" that by genocide.
> I'm not sure how you could interpret it like that.
Honestly this is how it reads to me.
Real science is complicated. It is very often -- maybe even most times -- the case that researchers can observe something happening, identify it, but not know what is the proximate cause.
Then, if they can identify the direct cause, that leads to the next problem: what caused that, building a chain of links, until they can say "we think it is this that is the root issue".
It is normal natural scientific caution to say "we don't know what causes this."
But it's an over-simplification. We do know what the ultimate cause is: human induced changes to the environment.
It is possible to both say "we don't know the reason" and to also know the root reason and for both statements to be correct.
Around the world, wildlife is dying off in large numbers. Even when it is not directly humans intentionally killing the organisms, it is caused by environmental damage caused by humans.
Saying it's not is like standing over a bleeding body, gloating, with blood-covered hands, and saying "I didn't kill him! The knife did!"
Yes, honey bee colonies are collapsing and the direct proximal cause is unidentified. However, that is a small facet of general large-scale collapse in insects in general: 85-90% in the last century.
That in turn is a big important faced of a general collapse in wild animals over that time, and indeed, over the last 2-2½ centuries.
The death of most wild animals is only a part of the death of countless plants, fungi, invertebrates, and microbes of various kinds.
You can't pin that down to a single cause, such as, say, DDT. There are lots of causes. But one thing caused all of them: human technological civilisation.
Before the Industrial Revolution, humans had already driven lots of species into extinction. Steller's Sea Cow, the Great Auk, the Dodo, all in documented history. Before historically recorded times, giant land sloths in South America, elephant birds and moas in New Zealand, and lots more.
But it's been exponentially increasing for about ¼ of a millennium, and the thing about exponenntial curves is that close to the end, where the rise is nearly vertical, all hell breaks loose and it becomes hard to trace the connections between phenomena and changes that are occurring very rapidly.
So the scientists say "we don't know". Which is true... but it is very clear who is causing it. It's us. Humans. It doesn't really matter if it's the chemicals that we make in the millions of tonnes specifically to kill insects, or the ones we make in the billions of tonnes to do other things which happen to kill insects, or the ones we accidentally create as byproducts which happen to kill insects, or whether it's because we're destroying the wilderness that they need to survive, or it's something we don't know yet.
E.g. vultures in India are doing very badly. It's humans, but it's by accident.
Some Indian religions practice "air burial". They let vultures eat the bodies.
Dying people often feel unwell. They take painkillers. Paracetamol is cheap. India is poor. People take a lot of paracetamol and then some of them die.
Paracetamol is toxic to vultures.
It's still humans, but it's indirect and accidental, but it's 100% our fault.