Bayes, Burdens and Base Rates
| Author | D.H. Kaye |
| Published date | 01 December 2000 |
| Date | 01 December 2000 |
| DOI | http://doi.org/10.1177/136571270000400403 |
| Subject Matter | Article |
Bayes, burdens and base
rates
By
D.
ti.
Kaye’
Regents’ Professor, Arizona State University
n
1997,
Professor Ronald Allen wrote:
Evidence has also experienced the demise of legal theorems. The
best example is the proofs that employing the civil burden of
persuasion of a preponderance of the evidence will minimise or
optimise errors. These are all false as general proofs (although
not as special cases), and all for the same reasons. They neglected
base rates and the accuracy of probability assessments of
liability, and virtually any relationship at all can exist between
subjective assessments of liability and the truth of factual
assertions at trial.’
Sandwiched around this claim were analogies to Darwin and Newton, and
talk of the tension between ‘algorithms’ and ‘formalisms’ on the one hand,
and ‘judgment’, ‘justice’, and ‘equity’, on the other2
When
I
observed that the proofs establish that a Bayesian decision rule
minimises expected losses
‘for
all possible base rates’? Professor Allen wrote
that
I
was ‘fascinatIed] with algorithms’? ‘blind
.
. .
to the deeper implications
of the work’ that
I
had cited.5 and that even though
I
teach evidence law,
I
did
I
am grateful to Ronald J. Allen for providing me with a prepublication copy of the paper
discussed here and to Brad Armendt
for
comments on my previous rejoinder to Professor
r
Allen.
1
Ronald
J.
Allen. ‘Rationality. Algorithms, and Juridical Proof:
A
Preliminary Inquiry’
(1997)
1
E
&
2
Ibtd.
at
255.
3
D.
H.
Kaye. ‘Statistical Decision Theory and the Burdens of Persuasion: Completeness. Generality.
4
Ronald J. Allen. ‘Reasoning and Its Foundation: Some Responses’
(1997)
1
E
&
P
343
at
345
5
Ibtd.
at
347.
P
254
(hereinafter Allen 1).
and Utility’
(1997) 1
E
&
P
313
at
314
(hereinafter Kaye I).
(hereinafter Allen
11).
260
THE INTERNATIONAL
JOURNAL
OF
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