Platitudes are a poor basis for policy. The reason is that, no matter how melodious they sound, platitudes are practically meaningless. People who utter platitudes often seem to be saying something meaningful when in fact they're merely stating the obvious.
A good way to test if someone is speaking in platitudes is to ask yourself if you can imagine a normal human adult believing the opposite.
Suppose someone informs you that he favors policies that promote human happiness. Can you imagine, say, your neighbor responding, “I disagree. I favor policies that promote human misery”? Probably not.
If you cannot imagine any normal person disagreeing with some proclamation, then that proclamation is a platitude. It tells you nothing of substance.
Consider today's fashionable calls for “sustainability.” The academy, media, cyberspace are full of people proclaiming support for policies that promote economic and environmental “sustainability.” So whenever you hear such proclamations, ask if you can envision a sane adult sincerely disagreeing.
You'll discover, of course, that you can't imagine anyone seriously supporting “unsustainability.” Therefore, you should conclude that mere expressions of support for “sustainability” are empty. And they can be downright harmful if they mislead people into supporting counterproductive government policies.
Substantive issues involving sustainability invoke questions that have non-obvious answers. For example: At what rate must the supply of a resource fall before we conclude that continued use of that resource is unsustainable? Fifty percent annually? Ten percent? One percent?
Because the correct answer to this question depends (among other factors) on how much humans care about the future — and because there's no good reason why we humans should care about the world as it might be many years from now as much as we care about the world as it might be a few days from now — policies and activities that will eventually result in the depletion of some resource are not necessarily unsustainable in any sense that really matters to humans today. If the appropriate human time horizon is, say, 500 years, then activities that will cause petroleum supplies to be exhausted in 550 years are “sustainable” within our relevant time horizon.
Economically sophisticated readers will respond, “Not so fast! Even if we won't completely run out of petroleum until well past the time that is relevant for human beings alive today, falling supplies of petroleum will start to raise the price of petroleum long before 500 years from now.” This claim is true — but it's a reason to worry less, not more, about “sustainability.”
A rising price of petroleum serves as a spur to sustainable practices. First, the rising price prompts consumers voluntarily to cut back on the use of petroleum. Second, this rising price creates incentives for entrepreneurs to find or create petroleum substitutes. And the steeper the price rise, the stronger are these incentives.
Nearly every resource commonly used today likely has potential substitutes — recall that newly discovered petroleum in the 19th century quickly substituted for wood, coal and whale oil. So to focus only on “sustainability” of resources commonly used today is to lose sight of the fact that these resources likely have substitutes that will become available if supplies of today's resources fall below critical levels.