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Sannolikhetslära och juridik - en perfekt match?

De Man Lapidoth, Adam LU (2018) JURM02 20181
Department of Law
Faculty of Law
Abstract
There have been claims put forth which aims at proving that the theories developed within mathematics, but also within economics to name one, regarding decision making and fact finding would suit very well to be adopted into the legal decision making as well. It is in this context primarily Bayes’ theorem which is referred and mentioned theorems compatibility with law. One of the first articles regarding this matter was an article written by John Kaplan in the late sixties. Bayes’ theorem is applicable whenever the probability of a hypothesis is to be determined by someone who is gradually presented with more and more evidence, which to some degree speak to the truth of the hypothesis. Bayes’ theorem also constitutes how one is supposed to... (More)
There have been claims put forth which aims at proving that the theories developed within mathematics, but also within economics to name one, regarding decision making and fact finding would suit very well to be adopted into the legal decision making as well. It is in this context primarily Bayes’ theorem which is referred and mentioned theorems compatibility with law. One of the first articles regarding this matter was an article written by John Kaplan in the late sixties. Bayes’ theorem is applicable whenever the probability of a hypothesis is to be determined by someone who is gradually presented with more and more evidence, which to some degree speak to the truth of the hypothesis. Bayes’ theorem also constitutes how one is supposed to reason, which aspects to consider and so on, when a value is to be put on any given evidence. Mentioned theorem seems, at first glance, to be perfectly suited for legal matters. But to investigate this matter further it is fundamental to examine what the legal decision making encompasses.

There are of course also those who claim that Bayes’ theorem actually not at all is suited for legal decision making, since it is mathematics and mathematics have nothing to do with legal matters. Furthermore, claims have been expressed that since the probability theory alone, at least not in some situations, cannot provide reason enough to convict the whole notion that probability theory has a place in law should be disregarded. Some of the arguments against the incorporation of Bayes’ theorem have been expressed as paradoxes.

Probability theory has been on the agenda for discussion in other scientific disciplines as well. A principally identical discussion was held within the scientific genre of physics from the thirties and forward. It is the controversial aspect of physics known as quantum physics that is meant. This discussion must be considered to have been won by the advocators of probability theory, since quantum physics today is considered a legitimate scientific field.

In the ongoing analysis the statements made in the literature regarding the application of probability theory to law is problematised. Several of the most essential aspects are readily analyzed. After a closer look at the questions at hand, and the arguments made from both sides, it is impossible to deny that probability theory in theory would be a perfect match for legal decision making. There are, although, a number of practical problems, which must be addressed. (Less)
Abstract (Swedish)
Det har hävdats att den teoribildning rörande beslutsfattande under osäkerhet som utvecklats främst inom matematiken, men även inom den ekonomiska vetenskapen bland andra, med fördel skulle kunna inkorporeras även i den juridiska disciplinen. I första hand är det i detta sammanhang Bayes sats som avses, och denna sats tillämplighet på juridiska spörsmål. Detta började diskuteras på allvar mot slutet av 60-talet, med startskott i en artikel av John Kaplan. Bayes sats syftar till att beskriva hur sannolikheten för att en viss hypotes är sann då den som skall utföra nyss nämda bedömning blir presenterad med olika evidens vilka talar för eller emot att denna hypotes är sann. Den talar även om hur man skall resonera och vilka principiella... (More)
Det har hävdats att den teoribildning rörande beslutsfattande under osäkerhet som utvecklats främst inom matematiken, men även inom den ekonomiska vetenskapen bland andra, med fördel skulle kunna inkorporeras även i den juridiska disciplinen. I första hand är det i detta sammanhang Bayes sats som avses, och denna sats tillämplighet på juridiska spörsmål. Detta började diskuteras på allvar mot slutet av 60-talet, med startskott i en artikel av John Kaplan. Bayes sats syftar till att beskriva hur sannolikheten för att en viss hypotes är sann då den som skall utföra nyss nämda bedömning blir presenterad med olika evidens vilka talar för eller emot att denna hypotes är sann. Den talar även om hur man skall resonera och vilka principiella aspekter som skall beaktas då man skall tillsätta ett värde på ett visst evidens. Detta verkar vid en första anblick passa alldeles utmärkt för juridiskt beslutsfattande. Men för att kunna svara på frågan så behöver man undersöka vad det juridiska beslutsfattandet verkligen innebär.

Dock finns det de som hävdar att denna metod inte alls är tillämplig då den i grund och botten är matematisk, och matematik har inget med juridik att göra. Vidare har det påståtts att eftersom sannolikhetsläran ensamt inte verkar vara tillräcklig för att dra några slutsatser rörande huruvida en domstol skall fria eller fälla så innebär detta att sannolikhetsläran inte är tillämpningsbar.Vissa av de argument som framförts mot att sannolikhetslära tar plats inom juridiken har formen av paradoxer.

Sannolikhetsläran har varit på agendan även rörande andra vetenskapliga genrer än juridiken. En principiellt identisk diskussion rörande sannolikhetslärans plats inom fysiken har förts från 30-talet och framåt. Det är alltså den inom fysiken kontroversiella kvantfysiken som åsyftas. Denna diskussion måste dock anses ha vunnits av förespråkarna för att sannolikhetslära bör användas, då kvantfysik idag är ett i allra högsta grad legitimt och vedertaget vetenskpligt fält.
I den löpande analysen så problematiseras de påståenden som framförts gällande sannolikhetslärans plats inom juridiken. Flertalet av de väsentliga aspekterna analyseras utförligt. Vid en närmare analys av de argument som framförts både för och emot så kan man inte påstå annat än att sannolikhetsläran rent teoretiskt bör passa alldeles utmärkt inom juridiken. Däremot finns det en rad praktiska problem vilka fortfarande väntar på en mer slutgiltig lösning. (Less)
Please use this url to cite or link to this publication:
author
De Man Lapidoth, Adam LU
supervisor
organization
alternative title
Probability Theory and Law - a Perfect Match?
course
JURM02 20181
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
allmän rättslära, bevisvärdering
language
Swedish
id
8941822
date added to LUP
2018-06-08 12:46:51
date last changed
2018-06-08 12:46:51
@misc{8941822,
  abstract     = {There have been claims put forth which aims at proving that the theories developed within mathematics, but also within economics to name one, regarding decision making and fact finding would suit very well to be adopted into the legal decision making as well. It is in this context primarily Bayes’ theorem which is referred and mentioned theorems compatibility with law. One of the first articles regarding this matter was an article written by John Kaplan in the late sixties. Bayes’ theorem is applicable whenever the probability of a hypothesis is to be determined by someone who is gradually presented with more and more evidence, which to some degree speak to the truth of the hypothesis. Bayes’ theorem also constitutes how one is supposed to reason, which aspects to consider and so on, when a value is to be put on any given evidence. Mentioned theorem seems, at first glance, to be perfectly suited for legal matters. But to investigate this matter further it is fundamental to examine what the legal decision making encompasses. 

There are of course also those who claim that Bayes’ theorem actually not at all is suited for legal decision making, since it is mathematics and mathematics have nothing to do with legal matters. Furthermore, claims have been expressed that since the probability theory alone, at least not in some situations, cannot provide reason enough to convict the whole notion that probability theory has a place in law should be disregarded. Some of the arguments against the incorporation of Bayes’ theorem have been expressed as paradoxes.

Probability theory has been on the agenda for discussion in other scientific disciplines as well. A principally identical discussion was held within the scientific genre of physics from the thirties and forward. It is the controversial aspect of physics known as quantum physics that is meant. This discussion must be considered to have been won by the advocators of probability theory, since quantum physics today is considered a legitimate scientific field. 

In the ongoing analysis the statements made in the literature regarding the application of probability theory to law is problematised. Several of the most essential aspects are readily analyzed. After a closer look at the questions at hand, and the arguments made from both sides, it is impossible to deny that probability theory in theory would be a perfect match for legal decision making. There are, although, a number of practical problems, which must be addressed.},
  author       = {De Man Lapidoth, Adam},
  keyword      = {allmän rättslära,bevisvärdering},
  language     = {swe},
  note         = {Student Paper},
  title        = {Sannolikhetslära och juridik - en perfekt match?},
  year         = {2018},
}