The Precautionary Principle and Pascal’s Wager

Reduced to its essence, the precautionary principle (PP) is this: Avert calamity regardless of the cost of doing so.

The thinking person, as opposed the the extreme environmentalist or global-warming zealot, will immediately and carefully pose these questions about the PP: What, specifically, is the calamity to be averted? How might it be averted? With what degree of certainty? What are the opportunity and monetary costs of the options?

Take death, for example. Most persons who are in good health (and even many who are in declining health) consider death to be a calamity. So, too, do their loved ones (usually). How, then, might death be averted, with what degree of certainty, and at what cost?

Death can be averted only temporarily. That is, death often can sometimes be postponed, but never defeated. So the question is how can it be postponed, and at what cost. Let’s take an extreme case of a man dying of a virulent cancer (confirmed by extensive tests and procedures) for which there is no known treatment, other than palliative care. What good will it do that man (or his heirs) to spend his fortune in search of cure for his disease? He will almost certainly die before a possible cure is identified and can be supplied to him. But in funding the search for a cure he would have followed the PP by doing his utmost to avoid the calamity of death, without regard for the calamity thereby visited upon upon his heirs.

In sum, the PP shouldn’t be followed in cases where:

  • there is nothing that human beings can do to avert the calamity, or
  • the cost of ameliorating the calamity is itself calamitous.

Extreme environmentalists and global-warming zealots are guilty of sub-optimizing. They focus on particular calamities, not on the big picture of human flourishing. Take global warming. It has been said many times that warming has many advantages, such as a longer growing season and a lower death rate (cold is a bigger killer than heat). It has also been shown that warming hasn’t been occurring as fast as projected. The over-estimation of warming is probably due to (a) overstatement of the effects of CO2 emissions on temperatures and (b) inadequate modeling that omits key factors. But the zealots remain undeterred by such considerations.

The only thing that’s saving humanity from total impoverishment at the hands of global-warming zealots is the ridiculously high cost of (probably futile) efforts to combat global warming. Shutting down coal mines is bad enough, though tolerable given the advances that have been made in the extraction of natural gas and oil. But there is little taste (except among well-fed elites) for shutting down factories, forcing everyone to drive battery-powered cars, shifting to high-cost and unreliable sources of energy (solar, wind, and hydro), forcing people to live in densely populated cities, and so on. And if all of those things were to happen, what difference would it make? Almost none.

Moreover, there is nothing unusual about the rising temperatures of recent decades, neither in rapidity nor level. As Bob Tisdale observes, during three global warming periods — 1916-1946, 1964-1993, and 1986-2015 —

there were similar observed changes in global surface temperatures. It’s tough to claim that the recent global warming is unprecedented when surface temperatures rose at a comparable rate over a 30-year timespan that ended about 70 years ago.

Second, climate models are not simulating climate as it existed in the past or present.  The model mean of the climate models produced for the IPCC’s 5th Assessment Report simulates observed warming trends for one of the three periods shown in this post. Specifically, during the three global warming periods discussed in this post, climate models simulated three very different rates of warming (+0.050 deg C/decade for 1916-1946, +0.155 deg C/decade for 1964-1993, and +0.255 deg C/decade for 1986-2015), yet the data from GISS indicated the warming trends were very similar at +0.16 deg C/decade and +0.166 deg C/decade. If climate models can’t simulate global surface temperatures in the past or present, why should anyone have any confidence in their prognostications of future surface temperatures?

Third, the models’ failure to simulate the rate of the observed early 20th Century warming from 1916-1945 indicates that there are naturally occurring processes that can cause global surfaces to warm over multi-decadal periods above and beyond the computer-simulated warming from the forcings used to drive the climate models [emphasis added].  That of course raises the question, how much of the recent warming is also natural?

Fourth, for the most-recent 30-year period (1986-2015), climate models are overestimating the warming by a noticeable amount. This, along with their failure to simulate warming from 1916-1945, suggests climate models are too sensitive to greenhouse gases and that their projections of future global warming are too high.

Fifth, logically, the fact that the models seem to simulate the correct global-warming rate for one of the three periods discussed [1964-1993] does not mean the climate models are performing properly during the one “good” period.

Despite such reasonableness, global-warming-zealot proponents of the PP are not to be deflected. For theirs is a religion, which seems to take Pascal’s wager seriously. Here’s Robert Tracinski on the subject:

Do you freaking love science? Then you might be a big enough sucker to fall for a claim like this one: “Across the span of their lives, the average American is more than five times likelier to die during a human-extinction event than in a car crash.” Which was actually made by an environmentalist group called the Global Challenges Foundation and reported with a straight face in The Atlantic….

There is something that sounded familiar to me about this argument, and I realized that it borrows the basic form of Pascal’s Wager, an old and spectacularly unconvincing argument for belief in God. (Go here if you want to give the idea more thought than it probably deserves.) Blaise Pascal’s argument was that even if the existence of God is only a very small probability, the consequences are so spectacularly huge — eternal life if you follow the rules, eternal punishment if you don’t — that it makes even a very small probability seem overwhelmingly important. In effect, Pascal realized that you can make anything look big if you multiply it by infinity. Similarly, this new environmentalist argument assumes that you can make anything look big if you multiply it by extinction….

If Pascal’s probabilistic argument works for Christianity, then it also works for Islam, or for secular versions like Roko’s Basilisk. (And yes, an “all-seeing artificial intelligence” is included in this report as a catastrophic possibility, which gives you an idea of how seriously you should take it.) Or it works for global warming, which is exactly how it’s being used here.

Pascal was a great mathematician, but this was an awful abuse of the nascent science of probabilities. (I suspect it’s no great shakes from a religious perspective, either.) First of all, a “probability” is not just anything that you sort of think might happen. Imagination and speculation are not probability. In any mathematical or scientific sense of the word, a probability is something for which you have a real basis to measure its likelihood. Saying you are “95 percent certain” about a scientific theory, as global warming alarmists are apt to do, might make for an eye-catching turn of phrase in press headlines. But it is not an actual number that measures something.


Tracinski later hits a verbal home run with this:

This kind of Pascal’s-Wager-for-global-warming is part of a larger environmentalist program: a perverse attempt to take our sense of the actual risks and benefits for human life and turn it upside down.

If we’re concerned about the actual dangers to human life, we don’t have to assume a bunch of bizarre probabilities. The big dangers are known quantities: poverty, squalor, disease, famine, dictatorship, war. And the solutions are also known quantities: technology, industrialization, economic growth, freedom.

Global-warming zealots are usually leftists, and leftists claim to be upholders of science. Yet they cling to two anti-scientific dogmas: the precautionary principle and Pascal’s Wager. As Tracinski says, “global warming has become a religion with a veneer of science.”