Transcript Ian Hacking Emergence of Probability Presentation Future

Thesis
• in the context of Western Europe
• modern scientific probability emerged after
about 1660
• probabilistic thinking is needed to prefer facts
to testimony and make reliable predictions
The Order of Slides
1. philosophical framework for Hacking’s theory
2. indications of a revolution in probability
science c. 1660
3. premodern concepts of probability
4. emergence of modern probabilty
5. consequences of the “taming of chance”
What is epistemology?
• the study of knowledge
• Greek “epistēmē”: knowledge
• meta: something that is about itself; selfreferential
• questions: What is knowledge? How do you
know that you know something? What is
opinion? What is impossible to know?
Michel Foucault
• The Order of Things (1962):
construction of scientific
knowledge in different eras
based on orderly,
subconscious structures
• episteme: underlying
system of understanding the
world; defines knowledge
and justified belief; essential
“order of things”
– How do you know that you
know something? How do you
know that it’s possible or
impossible to know
something?
1926–1984
Epistemes
• Ian Hacking’s thesis based in the context of
Western Europe’s underlying system of
understanding the world (episteme)
• modern scientific probability emerged
gradually after a revolution in probabilistic
thinking c. 1660
• emergence of probability symptomatic of a
larger epistemological revolution
• this had profound effects on the applications
of knowledge, such as statistics and
technology, and the way in which individual
people use knowledge
After 1660…
• changes in probabilistic thinking began
with a formally educated elite and
slowly trickled down over many
decades
– nations began to raise income by selling
annuities
– governments statistically analyzed births
and deaths
– gambling became a mathematical subject
– reliability of testimony in legal disputes
began to be evaluated statistically
Before 1660…
• data on births and deaths collected for
centuries was not used to make statistical
inferences
• long history of analyzing law and gambling did
not involve formal statistics
• nations lost money from selling annuities
because they failed to relate cost to the
purchaser’s age
• Ian Hacking: “I say, with only slight
reservations, that there was no probability until
about 1660.”
Why?
Modern Probability Concept
• Hacking: probability is dual
– epistemological: measuring the likelihood of
something based on support by evidence
– statistical: measuring likelihood based on
stable long-run quantitative frequencies
• “probability” as a holistic whole
measures credibility both qualitatively
and quantitatively
• in practice, statistical and
epistemological approaches to
knowledge are inseparable
Premodern Probability
Concept
• not a dual concept
• before c. 1660, scholars did not see
a relation btwn statistical laws of
chance processes & epistemological
assessments of reasonable degrees
of belief
• the word “probability” referred to a
qualitative assessment
Premodern Probability
Concept
• a “probable doctor” was a medical man
who could be trusted to perform well
• Edward Gibbon, 1776
– “Such a fact is probable but undoubtedly
false.”
• Daniel Defoe, 1724
– “This was the first view I had of living
comfortably indeed, and it was a very
probable way, I must confess, seeing we
had very good conveniences, six rooms on
a floor, and three stories high.”
Premodern Probability
Concept
• whenever someone said something was
“probable,” what they meant was that an
authority, such as a saint, king, or parent,
had vouched for it
• to some extent, determining the best decision
was always a moral question
• modern concepts of meritocracy and objective
evaluation of evidence generally “not possible”
before 1660
• statistics was not relevant to assessing the
correct thing to do or the correct way of
thinking
Pascal’s Wager (c. 1662)
• Pascal is often considered the
founder of probabilistic theory
• humans all bet with their lives
either that God exists or that
he does not exist
Blaise Pascal
1623–1662
Pascal’s Wager (c. 1662)
• Pascal is often considered the
founder of probabilistic theory
• humans all bet with their lives
either that God exists or that
he does not exist
• a rational person should live
as though God exists and
seek to believe in God
– if God does not actually exist,
you will have only a finite loss
– if God exists, you receive
infinite gains and avoid infinite
losses
Blaise Pascal
1623–1662
Pascal’s Breakthrough
• breakthrough in probabilistic thinking
• assumes isomorphism (structural
similarity) btwn:
1. decision making when objective physical
chances are known to exist (such as tossing
an evenly weighted coin) and
2. decision making when no objective physical
chances are known (such as the question of
the existence of God)
How Voltaire Made Baaaank
• in the early 18th century, the
French government attached a
lottery to the sale of
government bonds; however,
the prizes to be disbursed
substantially exceeded the
money to be gained in ticket
receipts
• Charles-Marie de La
Condamine and his friends,
including Voltaire, formed a
ticket-buying cartel that
gamed the broken system for
a profit
Voltaire
1694–1778
Consequences of Probability
Science
• focus of legal assessment of credibility gradually
shifts from testimony to factual evidence
– essential for later development of impersonal trial
procedure and rule of law
• essential for formation of modern states,
bureaucracies, and businesses
– “No British gov’t before 1789 appears to have
made the cost of annuity a function of the age of
the purchaser” due to lacking a “theory of the
relation between age at purchase and annual
payments.” Awkward.
Consequences of Probability
Science
• probability as a quantitative, mathematical tool
gave anyone who could understand the concept
a much more scientific way of making decisions
• empowered people to make decisions
independently
• essential for widespread and mathematically
sound investment
– instead of making investments based on religious
precepts or your personal association with the
investee
Consequences of Probability
Science
• freed decisions involving prediction and
assessment of accuracy and risk from
cultural values, religion, and hierarchy
• opinions were no longer sound only because
a high-status person had them
• opinions were sound because, in theory,
ideally, they could be objectively justified,
and because they satisfied your personal
standards of credibility
Thesis
• in the context of Western Europe
• modern scientific probability emerged after about
1660
• probabilistic thinking is needed to prefer facts to
testimony and make reliable predictions
• an epistemological revolution in probabilistic
thinking made possible the episteme of Western
Europe in modern times, and, by extension, political
and economic systems that Western Europe has
influenced in the last three hundred years