Dear all
the term "subjective" for probability was introduced by Bruno de Finetti,
and to understand the motivation it is necessary to understand the
cultural environment in Italy in that period. In 1934 Luigi Pirandello
received the Nobel Prize in Literature and his vision of life and
knowledge affirmed that there was no 'single truth' but reality was
what the individual subject perceived. And this is also evident from
some of the best-known titles of his plays ( Cosi e' se vi pare, Uno
nessuno centomila).
de Finetti grows in this cultural context but gives to the term
"subjective" a value more rigorous and "objective" through the
concept of coherent betting.
Personally, I do not believe that the term subjective is to be
understood in a negative way because it highlights how the knowledge
an individual has about a phenomenon depends on the information the
subject has.
For this reason, in the subjectivist approach to probability, the
concept of conditional probability and conditioning events are
fundamental to represent respectively partial knowledge and different
information that individuals have.
Best regards,
Serena Doria
"Kreinovich, Vladik" <vladik(a)utep.edu> ha scritto:
Dear Friends,
We often talk and write about objective and subjective
probabilities, about objective and subjective measures of
uncertainty. However, at a recent conference on uncertainty, Yakov
Ben-Haim made an important observation -- based on his experience of
working on applications with colleagues from many different areas.His experience is that in many application areas, the word
"subjective" has a negative connotation: it means unjustified
estimates based on gut feeling only, prone to bias and wild
variations.Such gut-feeling-based estimations sometimes happen, but mostly,
when we talk about "subjective", we mean judgmental estimates,
estimates which are not just coming out of gut feeling, but which
can be usually provided with some justification. For example, if we
estimate to what extent someone is young (one of Zadeh's original
examples) we can usually explain the degree we assign to "youngness"
of an individual by referring to features which are present and
which are typical young age - and features of this individual which
are more typical for mature-age folks.For example, subjective probability often means simply probability
that is not coming from the analysis of frequency, but from expert
estimates.Yakov's recommendations is to use words like "judgmental" (or
"expert-based") instead of "subjective" in such situations,
especially when working on applications - and applications are the
main goal of uncertainty studies in the first place.