Sustainability: Part II
The generally accepted definition comes from the Brundtland Report, which defines sustainable development as: "development that meets the needs of the present without compromising the ability of future generations to meet their own needs".There are two problems with this definition. The first is that implementing it requires us to predict what the future will be like in order to know what the needs of future generations will be. Consider two examples:
1. The cost of solar power has been falling steeply. If that fall continues, in another couple of decades fossil fuels will no longer be needed for most of their current purposes, since solar will be a less expensive alternative. If so, sustainability does not require us to conserve fossil fuels.
2. A central worry of environmentalists for at least the past sixty years or so has been population increase. If that is going to be the chief threat to the needs of future generations then sustainability requires us to keep population growth down, as many have argued.
A current worry in developed countries is population collapse, birth rates in many of them being now well below replacement. With the economic development of large parts of the third world, that problem might well spread to them. If so, sustainability requires us to keep population growth up, to protect future generations from the dangers of population collapse and the associated aging of their populations.
It's easy enough to think of other examples. Generalizing the point, "sustainability" becomes an argument against whatever policies one disapproves of, in favor of whatever policies one approves of, and adds nothing beyond a rhetorical club with which partisans can beat on those who disagree with them.
There is a second and related problem with the definition: whether it is to be defined by individual effects or net effects. If a particular policy makes potable water less available to future generations, with the result that many of them get drinking water in bottles rather than from the tap, but also makes future generations enough richer to more than pay the cost of that bottled water, is that policy consistent with sustainability?
Or consider the issue of global warming. Assume that it can be slowed or prevented, but at the cost of slowing the development of much of the world. To make the point more precise, suppose that global warming imposes an average cost on future generations of 10 utiles (or whatever unit you prefer to use to measure the ability of future generations to meet their own needs), but the policies that prevent it impose a cost of 20. Is permitting global warming sustainable? Is preventing it?
If we define sustainability in terms of individual effects, treating as unsustainable anything which makes future generations less able to meet any one of their needs, there may be no policies at all that are sustainable, since each alternative alters the future in different ways and any alteration is likely to be bad in at least one respect. If, more plausibly, we define it in terms of net effects, then the demand for sustainability turns into the demand that we not follow policies that make future generations worse off than the present generation.
What policies make future generations better or worse off is one of the things people who argue about policy disagree about. It was obvious to a large number of intelligent and thoughtful people early in the past century that socialism made people better off; it is obvious to most such people now that it had the opposite effect. Similarly with current arguments over almost anything, from gay marriage to genetically engineered crops. "Sustainability" becomes an argument for both sides, each interpreting it by its view of the consequences of the policies it supports or opposes.
Not only does the requirement of sustainability add nothing useful to the conversation, it takes something away. It implies that the one essential requirement is making sure our descendants are as well off as we are; whether they end up better off than we are, as we are better off than our ancestors, is relatively unimportant. That surely impoverishes any serious discussion of policies that affect future generations.
I am grateful to the commenter for providing me with a definition, but it does not alter my conclusion. To regard sustainability as a useful and important goal is indefensible.