Volume 3, April 2003
Stephen F. Haller’s Apocalypse Soon? Wagering on Warnings
Elizabeth A. Corley, Ph.D. **
University Press: Montreal & Kingston, 2002, 185 pages.
Professor, School of International and Public Affairs, Columbia University
do we make policy decisions to avert potential global catastrophes when
predictions from scientific models are highly uncertain? In his book, Apocalypse Soon? Wagering on
Warnings of Global Catastrophe, philosopher Stephen Haller provides an
answer to this timely question.
Throughout the book, Haller addresses the varying levels of risk
regarding global catastrophes and he proposes how we might move forward with policy-making
regarding these risks, even though scientific information about the future is
often sparse or non-existent. Haller’s
arguments are presented in a clear and concise way that makes this book both
engaging and accessible.
main objective of Haller’s book is to explore how environmental policies should
be made in the face of great scientific uncertainty - the type that we find
with global warming models. Haller
argues that current and historical warnings from scientists about global
catastrophes like overpopulation, global warming, nuclear winter, and
ozone-layer depletion are mixed blessings.
On the one hand, they may help us avert potential global disaster but,
on the other hand, they can tie up resources and immobilize policy-making as we
attempt to avoid a disaster that might never come to pass. He discusses the use of scientific models in
predicting levels of risk for global disasters (such as global warming) while
arguing that we should place little confidence in these models and their
predictive abilities because the large-scale nature of global models makes it
impossible for their developers to test against their predictions and improve
the models by trial and error.
the potential costs of global catastrophe are so high and the level of risk is
unknown, how do we make policies based on this mixed information? Do we assume that the models are correct and
prepare for the worst case scenario? How
do we evaluate scientific models that predict global catastrophe to determine
if they are credible? These are a few of
the questions that Haller specifically addresses in the book.
Part I of this book (Chapters 1 – 6), Haller outlines several examples of past
and present global models and he discusses how these models are usually evaluated. In Chapter 1, Haller presents examples of
global systems models that predict large-scale catastrophes; specifically, he
explores the history of nuclear winter models, ozone depletion models,
overpopulation models, and global warming models.
Chapter 2, Haller discusses the nature of scientific models and explains how
the two model goals of explanation and prediction can contradict each
other. Some models, such as models of
traffic circulation, can provide both an explanation and prediction of the future. If a model, however, is only able to yield
either an explanation or a prediction (but not both), then the model will be
rejected or accepted based only on the successful property.
Chapter 3, Haller presents several criteria for assessing whether or not any
prediction can serve as a good test of a model.
Usually, scientists tinker with models to assess their reliability, but
in the case of global warming, the confirmation of predictions will come too late
to be helpful for policy makers. He argues
that “the nature of the problem in question is that we are urged to take
immediate action before predictive
success is possible.”
Chapter 4, Haller explores options for testing whether a model can accurately
predict future conditions without waiting to see if those predictions come to
pass. He argues that to accurately evaluate a predictive, scientific
model three issues must be addressed: 1) how accurate are the initial data that
we supplied to the model?, 2) how reliable is the model?, and 3) are the
probabilities the model assigns to predictions justified? Haller believes
that global models are weak in all three of these areas.
Chapters 3 and 4, Haller presents traditional methods for evaluating scientific
models using trial and error or “direct tests” of the models. In Chapter
5, however, Haller presents “indirect tests” of models and says that these
tests allow scientists to evaluate theories and models even when trial and
error cannot be used. Indirect tests of a model’s strength for prediction
utilize historical agreement, predictions in the near future, sensitivity
analysis, and analogues to similar physical phenomena. Haller discusses
each of these indirect tests in detail and applies them to global warming
models. He concludes that neither indirect tests nor direct tests of
global warming models instill confidence in the models.
summarizes his concerns about the explanatory and predictive powers of global
warming models in Chapter 6. He is
especially concerned with epistemic difficulties that are “peculiar to the
problem of assessing a model’s reliability without the benefit of direct
testing through trial and error.” In the case of global scientific models, the
epistemic problem is that model predictions could be simple logical
implications that provide information about what is possible, but they may not
give us any sense of the most likely scenario.
In short, we use global models and we either expect that they will be
applicable to the situation at hand (such as global warming) or that they will
not be applicable. If the model is
deemed applicable, it exhibits successful explanation and prediction of
phenomena and we are satisfied with it.
On the other hand, if the model’s predictions do not match our
observations, we might still be satisfied with it and just explain why the
observations deviated from the ideal case.
Haller argues that we never know beforehand if a model is applicable or
not; when models are used as an ideal, they cannot be falsified. If any explanation of the deviation of
observations from the ideal is required, it is not supplied by the model. These types of explanations are supplied by
the researcher and are value-laden.
Part II of his book (Chapters 7-10), Haller explores the role of traditional
decision-making theory as a tool for guiding actions regarding potential global
catastrophic events. He points out that it is difficult (if not
impossible) for policy-makers to react cautiously to every risk that is
presented to them. In Chapter 7, Haller
argues that “science by itself cannot drive policy because other values must
figure in decision-making.” Even if existing global warming models did
give us comprehensive scientific probabilities about global catastrophe, we
would not make policy decisions based solely on the science; desires and values
are also part of the policy-making process.
Chapter 8, Haller explores the strengths and weaknesses of the precautionary
principle as a tool for policy-making when faced with conditions of extensive
scientific uncertainty. He presents the
concept of “epistemic conservatism,” which is the maxim that science follows
when either a Type I or Type II error is unavoidable. Epistemic conservatism is defined as the
concept that new theories or models are treated with skepticism until they are
proven to be valid and useful. Haller
argues that if we adopt this notion of epistemic conservatism for dealing with
models of global warming, the “burden of proof will lie with those who assert
that there is such a risk, rather than with those who want to continue
this approach would protect us from over-reacting to the threat of global
warming, it could also lead to global disaster if the models that predict dire
consequences of the warming prove to be true.
Haller says that we need to know if “there are any good prudential or
moral reasons for escaping epistemic conservatism when confronted with the
possibility of global disaster.” He believes that in the case of zero-infinity
dilemmas, cost-benefit analysis does not provide a sufficient decision-making
framework because making decisions in cases of low probability is quite
difference from decision-making in cases of uncertain probability. Haller turns to the concept of the
precautionary principle as an alternative decision-making framework for
zero-infinity dilemmas. Adopting the
precautionary principle as a basis for decision-making in cases of uncertainty
transfers the burden of proof to those who are skeptical about global warming
Chapter 9, Haller presents arguments by scholars who have called for new
conceptions of rationality. These
scholars argue that this new concept of rationality should place more emphasis
on ethical and democratic values because decision-making about global risks is
mostly a matter of ideology anyway; therefore, we should openly embrace making
decisions based on political, ethical, and cultural reasons, rather than acting
as though we are making decisions based on scientific certainty. Haller disagrees with this view because he
argues that it is a “result of running together epistemic values and action-guiding
– that is, it does not distinguish between claims that something is the case
and claims that a particular type of action should be taken.
Chapter 10, Haller revisits the precautionary principle and points out that
while epistemological arguments provide support for the concept of epistemic
conservatism, ethical arguments provide support for the precautionary
principle. Some scholars use moral
arguments to override the problems with the precautionary principle – they
argue that some risks are not morally justifiable. Haller says that ethical arguments in support
of the precautionary principle “shift the burden of proof to those who claim
that no harmful effects will occur.” Haller criticizes five ethical arguments that
could support use of the precautionary principle; he concludes that these
arguments cannot generate sufficient, widespread support of the precautionary
Haller borrows arguments from Pascal and William James to argue that we must
embrace the precautionary principle in cases of scientific uncertainty, such as
global warming. Following Pascal, Haller
suggests “that if one allows the perceived high costs of precaution to sway
against precautionary action, then one just does not understand the infinite
costs of catastrophe.” Haller argues that Pascal’s Wager, which lays
out why one should believe that God exists, is not about belief, rather is
about a gamble. Even if there is a very
small probability that God exists, we should bet on it because the magnitude of
the potential reward of the decision is so great. Haller argues that the principles of gambling
in Pascal’s Wager and global warming are similar. Even if the costs of acting like global
catastrophe will occur are tremendously high, they are “nothing compared to the
infinite negative value of a catastrophe.” Thus, when we make a bet in favor of the
occurrence of global warming (of the existence of God) we are not believing,
rather we are acting. Haller concludes
that we do not necessarily need to believe that global catastrophe will occur,
as long as we act to prevent catastrophe.
following William James, Haller claims that “deciding a course of action on
nonintellectual grounds, which the arguments for precaution specifically call
for, is justified under certain conditions – conditions that define what James
calls a genuine option.” Haller agrees
with James that “there are certain momentous decisions that must be made under
uncertainty and, in these cases, the caveat of scientific reasoning to suspend
judgment is misplaced.” An option is momentous if the situation would
lead to a decision that is irreversible or if the stakes are particularly
argues that Pascal and James’s arguments provide reasons for action, but not
necessarily for belief. He says that if
we act on the hypothesis that God exists, “both Pascal and James point out that
the benefits of this action will have an immediate pay-off and might even have
an infinite pay-off in the afterlife.
These are reasons for faith.” Haller believes that the same is true for
having faith that global warming is occurring.
Haller says that “the evidence from the models does not provide
sufficient evidence for belief, and this is why they fail to convince
everyone. However, they do provide
reasons for action.” We merely must accept these models as working
summary, Stephen Haller provides a comprehensive criticism of the reliability
of global warming models and a deft exploration of the concept of policy-making
in cases of potential global catastrophe.
This book clearly and consistently demonstrates that the prediction
abilities of many global warming models are weak and cannot serve as a sufficient
basis for calculating the probability of global catastrophe. One complaint however is that Haller presents
arguments against the predictive powers of global catastrophe models, but
discusses the models in the abstract without focusing on the specifics of a few
of the widely accepted global warming models.
Therefore, a reader without extensive knowledge of the science behind
global warming models might wonder if the weaknesses that Haller presents are
common to all models or simply a few of them (i.e., can each of these models
have all of these weaknesses?). If
Haller had introduced the specifics of a few of the more widely accepted
models, I think that the reader would be left with a better sense of the
strengths and weaknesses of the models.
However, this focus would have lead to a different (and doubtless much
the book, Haller’s philosophical arguments are presented in a thoughtful and
engaging manner that is accessible to a broad range of audiences. The organization of the book is particularly
strong. Haller guides the reader through
his arguments from beginning to end.
First, he presents the weaknesses of global catastrophe models and then
explains to the reader why policy-makers must heed the warnings of these models,
despite their weaknesses. While some
readers might not agree with Haller’s evaluation of current global catastrophe
models and his discussion of their weaknesses, most readers will find his
arguments noteworthy and thoughtful.
conclusion, Stephen Haller has written a thoughtful book that is accessible to
a broad range of audience types and would be of interest to philosophers,
scholars of policy studies, natural scientists, and social scientists, as well
as practitioners, policy-makers, and the general public.
R. C. (1983). The Logic of Decision. Second edition. Chicago:
University of Chicago Press.
Keeney, R. L., and
H. Raiffa. (1976). Decisions with Multiple
Objectives: Preferences and Value Tradeoffs. New York: Wiley.
Lindblom, C.E. (1965). The Intelligence of Democracy. New
York: Free Press.
J.G. and H.A. Simon (1958). Organizations. New York: Wiley.
Raiffa, H. (1968). Decision
Analysis: Introductory Lectures on Choices Under Uncertainty. Reading, MA:
H.A. (1947). Administrative Behavior. New York: Macmillan.
H.A. (1957). Models of Man. New York: Wiley.