It's much easier to tell people what they want to hear than to tell them what they need to hear. This is the first and most important advantage a cornucopian thinker has when arguing before any audience. No one really wants to hear that the future may be filled with turbulent change and personal insecurity.
Perhaps more difficult to overcome is the argument that the future will be like the recent past--meaning the last couple of fossil-fueled centuries--only better. By definition there can be no proof of such an assertion. But the human tendency to extrapolate the recent past (meaning my lifetime of experiences) into the future is almost universal. When the ecological truthteller offers a different scenario, the burden of explanation is on him or her to show why the future will be different; the cornucopian is not required to mount a case other than to say something vague such as, "Everything has worked out fine so far, even though the pessimists predicted catastrophe."
This is nothing more than the problem of induction which is unfathomable to many people unless it is explained very simply. One writer relates a story told by Bertrand Russell that attempts to do just that:
I prefer another tale told by Bertrand Russell, which concerns a certain farmer and his turkey. From the point of view of the reflective turkey, the farmer will always greet him in the morning with a bucket of grain. Why? Because, by simple inductive reasoning, it follows that the more often this happens, the more secure [the turkey] is in the belief that it will happen again until, one morning, the farmer appears with an axe. Now from the farmer's better informed point of view, he knows that the more often the turkey gets the grain, the less likely it is that he will survive another day. Similarly, life underwriters adopt the farmer's point of view.
We mistake frequency of an event for proof that it will continue in the future.
Cornucopians also like to talk about how much better off nearly everyone in the world is now than in the recent past. Again, because most people have difficulty understanding the problem of induction, this claim is hard to battle. But the clever debater will show that the cornucopian is focused only on human welfare in the very short term. The eco-services that humans rely on for clean water, food production, and stable climate are actually on different and deteriorating trajectories. If the very basis for our material well-being is declining dangerously, then society's feeling of well-being will someday reverse. The big question is when.
Since the ecological truthteller must now come up with a date to satisfy the audience's curiosity, he or she will offer one from the literature on global warming or water depletion or some other predicted ecological crisis. If the date is nearby, the truthteller will be subject to short-term falsification (and, in addition, to the feeling among the audience that something so horrible couldn't happen so soon and that the speaker is merely engaging in fearmongering). If he or she chooses a distant date, the audience may not see the importance of doing anything. Keep in mind that dates 20 years or more in the future seem distant to most people, and they are inclined to believe that the intervening time will be sufficient to think up and implement solutions for a known problem.
Above all, cornucopians love to argue that even if many environmental problems exist, we will think up ways to solve them because we always have. They will cite clean air and clean water as successes. This is the problem of induction with a twist. It is not just faith that current trends can be endlessly extrapolated into the future, but faith that problems which could derail those felicitous trends and for which there are currently no solutions will be miraculously solved. It is as if the turkey in Bertrand Russell's story knows that the axe has fallen with regularity on other turkeys, but somehow believes that the axe "problem" will be solved before his number is up.
To offer a definite date in the future for anything (except maybe recognized holidays) is a fib. The cornucopian will easily trip up anyone claiming to be an ecological truthteller and turn him or her into a ecological liar. The calendar is already littered with disaster predictions that have not (yet) come true.
But the tables can be turned on the cornucopian who likes to speak in certainties just as much as the ecological truthteller inadvisably does. We live more or less in a probabilistic universe about which our knowledge is highly imperfect. In our daily lives, however, we unconsciously know this. We take out insurance against risks which may never strike us, but the consequences of which could be catastrophic. We buy fire insurance on our homes, for example, even though home fires large enough to justify an insurance claim are very rare. Yet, we do it because we know that home fires have been known to wipe out people financially.
The cornucopian has no more knowledge about the future than anyone else. And yet, even as he or she conveniently ignores negative trends, the cornucopian also tells us not to bother with insurance in the form of mitigating global warming or creating a sustainable society.
The ecological truthteller now has the opportunity to fight the arrogant certitude of the cornucopian with a dose of risk assessment as follows: "Given that the consequences of global warming and resource depletion could be severe--so severe that they could bring down our modern civilization--and even if you believe that the chances of such severe consequences are small, wouldn't it be worth it to take out some insurance just in case? And, if you believe we should do nothing, why are you paying to insure your home against catastrophic but very rare occurrences such as fires? As for the date of the onset of any demonstrable crisis that we will feel personally, well, we are all like Bertrand Russell's turkey. We simply don't know when it will happen. But, unlike the turkey, we've been warned."