Dear Serena, Thank you for this clarification of de Finetti's cultural surroundings. I've heard it said that the data are the data, and everything else we made up. (Sometimes it turns out that what one thought were data , turn out not be the data, but that's another issue). We may have better or worse reasons for the model, prior, etc. used in an analysis, and to be persuasive, it is necessary to explain the thought process behind the choices made. Sometimes the word "objective" is used to try to intimidate people from challenging the choices made. All the best, Jay Kadane
On 2/18/21 3:36 AM, Serena Doria wrote:
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.
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