Part C | 26.1
568 Part C Coastal Design
powers beyond our control or understanding. There is
no concept of risk in such cultures beyond the fear of
certain punishment should you anger the powers that
be. The roots of our conception of risk arose in the Renaissance, as cultures in the west broke away from and
challenged long-held beliefs. One of the critical turning
points for the concept of risk as we know it was the development of the concept of probability – the idea that
the future was not determined or unpredictable, but that
there was the possibility to make predictions based on
numbers, not oracles or soothsayers. The origin of this
truly revolutionary concept is recounted by Bernstein as
follows [26.1]:
In 1654, a time when the Renaissance was in full
flower, the Chevailier de Mere, a French nobleman
with a taste for both gambling and mathematics,
challenged the famed French mathematician Blaise
Pascal to solve a puzzle. The question was how to
divide the stakes of an unfinished game of chance
between two players when one of them is ahead.
The puzzle had confounded mathematicians since
it was posed some 200 years earlier by the monk
Luca Paccioli . . . Pascal turned for help to Pierre
de Fermat, a lawyer who was also a brilliant mathematician. The outcome of their collaboration was
intellectual dynamite. What might appear to have
been a seventeenth-century version of the game of
Trivial Pursuit led to the discovery of the theory of
probability, the mathematical heart of the concept
of risk.
Hence, imbedded in the concept of risk is the inherent belief in predictability, at least in a probabilistic
sense. This concept, however imbedded in our current
culture, stands in stark contradiction to the well-known
adage that one cannot accurately predict the future. In
the modern world, this contradiction is resolved through
the belief that if we knew enough, we could accurately
predict the future. This belief in scientific determinism
(the same concept from ancient times that was overturned by the concept of risk) was articulately stated
by Pierre-Simon Laplace in his landmark 1812 treatise
Essai philosophique sur les probabilités (A Philosophical Essay on Probabilities as translated by Truscott and
Emory in 1902) [26.2]:
We may regard the present state of the universe as
the effect of its past and the cause of its future. An
intellect which at a certain moment would know all
forces that set nature in motion, and all positions
of all items of which nature is composed, if this intellect were also vast enough to submit these data
to analysis, it would embrace in a single formula
the movements of the greatest bodies of the universe
and those of the tiniest atom; for such an intellect
nothing would be uncertain and the future just like
the past would be present before its eyes.
We have therefore, in many ways, come full circle
as a culture. Through the concept of risk we have moved
away from the underpinning belief in determinism to
accept that there is an unknown and unknowable future.
Yet, through the application of mathematical probabilities, which gave rise to the concept of risk, we also have
developed the idea of a scientific determinism, wherein
if all lack of knowledge could be eliminated through
scientific inquiry, we would once again have a certain
and determined future.
The cultural concept of scientific determinism
through the elimination of uncertainty and evaluation
of undetermined but manageable future options are the
heart of risk assessment. The purpose of the study of
risk is to manage the future by using our best knowledge and current understanding to reduce uncertainty
and quantify the remaining uncertainty through probabilistic prediction.
26.1.1 Definitions of Basic Terms
Because the concepts of risk and uncertainty are now so
ingrained into our society, the use of terms associated
with risk and uncertainty, including hazard, probability, risk assessment, risk analysis, and in fact the
words risk and uncertainty themselves, are used frequently in differing and often confusing ways. When
one adds to this situation the fact that risk and uncertainty inherently rely on other ill-defined and often
misused concepts such as error and variability, it becomes apparent that before entering into a discussion
of the application of hazard probability and risk assessment to coastal systems, it is necessary to ensure
that there is a consistent and uniform understanding
of terms. A full list of definitions for probability and
risk related terms used in describing coastal hazards is
given in the Sect. 26.A; however, several key definitions
are retained here that are most pertinent to discussions
within this chapter:
Probability: In its most basic sense, probability is
the chance or likelihood that something will happen. Qualitatively, the more likely an event is to
happen, the more probable the event. Quantitatively,
probability is a value between 0 and 1, with 1 representing absolute certainty of the event occurring.
The probability of an event is typically measured as
the ratio of the number of times an event occurred
over the total number of times the event could have
occurred. For example, if we consider the event to
be the occurrence of precipitation on any given day,
568 Part C Coastal Design
powers beyond our control or understanding. There is
no concept of risk in such cultures beyond the fear of
certain punishment should you anger the powers that
be. The roots of our conception of risk arose in the Renaissance, as cultures in the west broke away from and
challenged long-held beliefs. One of the critical turning
points for the concept of risk as we know it was the development of the concept of probability – the idea that
the future was not determined or unpredictable, but that
there was the possibility to make predictions based on
numbers, not oracles or soothsayers. The origin of this
truly revolutionary concept is recounted by Bernstein as
follows [26.1]:
In 1654, a time when the Renaissance was in full
flower, the Chevailier de Mere, a French nobleman
with a taste for both gambling and mathematics,
challenged the famed French mathematician Blaise
Pascal to solve a puzzle. The question was how to
divide the stakes of an unfinished game of chance
between two players when one of them is ahead.
The puzzle had confounded mathematicians since
it was posed some 200 years earlier by the monk
Luca Paccioli . . . Pascal turned for help to Pierre
de Fermat, a lawyer who was also a brilliant mathematician. The outcome of their collaboration was
intellectual dynamite. What might appear to have
been a seventeenth-century version of the game of
Trivial Pursuit led to the discovery of the theory of
probability, the mathematical heart of the concept
of risk.
Hence, imbedded in the concept of risk is the inherent belief in predictability, at least in a probabilistic
sense. This concept, however imbedded in our current
culture, stands in stark contradiction to the well-known
adage that one cannot accurately predict the future. In
the modern world, this contradiction is resolved through
the belief that if we knew enough, we could accurately
predict the future. This belief in scientific determinism
(the same concept from ancient times that was overturned by the concept of risk) was articulately stated
by Pierre-Simon Laplace in his landmark 1812 treatise
Essai philosophique sur les probabilités (A Philosophical Essay on Probabilities as translated by Truscott and
Emory in 1902) [26.2]:
We may regard the present state of the universe as
the effect of its past and the cause of its future. An
intellect which at a certain moment would know all
forces that set nature in motion, and all positions
of all items of which nature is composed, if this intellect were also vast enough to submit these data
to analysis, it would embrace in a single formula
the movements of the greatest bodies of the universe
and those of the tiniest atom; for such an intellect
nothing would be uncertain and the future just like
the past would be present before its eyes.
We have therefore, in many ways, come full circle
as a culture. Through the concept of risk we have moved
away from the underpinning belief in determinism to
accept that there is an unknown and unknowable future.
Yet, through the application of mathematical probabilities, which gave rise to the concept of risk, we also have
developed the idea of a scientific determinism, wherein
if all lack of knowledge could be eliminated through
scientific inquiry, we would once again have a certain
and determined future.
The cultural concept of scientific determinism
through the elimination of uncertainty and evaluation
of undetermined but manageable future options are the
heart of risk assessment. The purpose of the study of
risk is to manage the future by using our best knowledge and current understanding to reduce uncertainty
and quantify the remaining uncertainty through probabilistic prediction.
26.1.1 Definitions of Basic Terms
Because the concepts of risk and uncertainty are now so
ingrained into our society, the use of terms associated
with risk and uncertainty, including hazard, probability, risk assessment, risk analysis, and in fact the
words risk and uncertainty themselves, are used frequently in differing and often confusing ways. When
one adds to this situation the fact that risk and uncertainty inherently rely on other ill-defined and often
misused concepts such as error and variability, it becomes apparent that before entering into a discussion
of the application of hazard probability and risk assessment to coastal systems, it is necessary to ensure
that there is a consistent and uniform understanding
of terms. A full list of definitions for probability and
risk related terms used in describing coastal hazards is
given in the Sect. 26.A; however, several key definitions
are retained here that are most pertinent to discussions
within this chapter:
Probability: In its most basic sense, probability is
the chance or likelihood that something will happen. Qualitatively, the more likely an event is to
happen, the more probable the event. Quantitatively,
probability is a value between 0 and 1, with 1 representing absolute certainty of the event occurring.
The probability of an event is typically measured as
the ratio of the number of times an event occurred
over the total number of times the event could have
occurred. For example, if we consider the event to
be the occurrence of precipitation on any given day,