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An assertion is a statement to be proved. The ability of evidence to prove
an assertion is measured by the probability the assertion is true. FactLogic
determines the probability an assertion is true
for a number of independent facts.
Evidence
can be evaluated to determine the effects from different
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probabilities,
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facts,
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suspects,
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standards
of proof,
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fact
finders, etc.
Generally,
FactLogic can be a tool for investigation and research, such as for the reevaluation
of unsolved cases.
The probability an assertion is true can be either determined by one
evaluator (Section
3) or analyzed by multiple evaluators (Section 4).
1. Classifications
of Evidence
Facts must be independent: Two facts are independent
if your knowledge of one does not influence your probability of the
other. If two or more facts appear to be dependent, combine
them to create a single compound fact that is independent
of the others.
Evidence
can be classified according in a variety of ways: direct or circumstantial,
inculpatory (i.e., incriminating) or exculpatory, material or immaterial
(which can be relevant or irrelevant), admissible or inadmissible, etc.
Evidence that is classified as direct or circumstantial and inculpatory
or exculpatory are particularly relevant to evaluation.
1.1
Direct and Circumstantial Evidence
Direct
Evidence. Direct evidence is the testimony of a witness to the issue.
The witness sensed (i.e., saw, heard, touched, tasted, or smelled) the
issue in question. Direct evidence directly proves a fact, without an
inference or presumption, and which in itself, if true, conclusively
establishes that fact. In terms of FactLogic, the fact finder would
judge the probability of truthfulness of the testimony, and list the
other two probabilities of either responsibility or non-responsibility
as either 0% or 100%. Direct evidence that is material is admissible.
The probability of truthfulness of testimony can be very low.
Circumstantial
Evidence. Evidence that is not direct is circumstantial. Circumstantial
evidence is not based on personal knowledge or observation; but it is
based on facts from which deductions are drawn. In terms of FactLogic,
the fact finder would judge the probability of truthfulness of the evidence,
and judge the other two probabilities an assertion is true or non-responsibility
(but not necessarily as either 0% or 100%, as is done with direct testimony).
1.2
Inculpatory and Exculpatory Evidence
Evidence
can be classified as inculpatory (i.e., incriminating), exculpatory,
or both:
Inculpatory
Evidence. Inculpatory facts are those that tend to prove an assertion.
Exculpatory
Evidence. Exculpatory facts are those that tend to prove disprove an
assertion.
FactLogic
combines both types of evidence. Analysis is more accurate as more facts
are included, as long as well-reasoned probabilities are provided.
2.
Factors of Evaluation
Evidence can be evaluated alternatively by changing probabilities, facts,
suspects, and fact finders. The probability an assertion is true can also
be compared to various standards of proof.
2.1
Compare Probabilities
Each fact is evaluated by assigning a probability that it is true
and a probability that it either proves or disproves an assertion, given
that it is true. Various probabilities can be assigned to facts in order to
observe their effect on the probability an assertion is true.
2.2
Compare Facts
Include
all independent facts that you want to evaluate. An fact can be omitted from the calculation by either entering
sero
or leaving blank the 'Probability Fact is True.' FactLogic ignores the
fact if the probability that the fact is true is either zero or left blank.
Using different combinations of facts can test their effects upon the
probability an assertion is true for purposes such as the following:
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Uncertainty
about Inclusion. You might be unsure whether an fact
will be or should be considered.
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Determine
Effect. You might want to determine the influence of a single fact
upon the overall probability an assertion is true.
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Appeal.
If evidence is discovered after a trial, you can include it and determine
its effect on the outcome.
2.3
Compare Assertions (e.g., Potential Suspects)
A case
often involves a number of potential suspects. FactLogic can determine the probability
an assertion is true of each potential suspect so they can be compared. When FactLogic
is used to compare potential suspects, the probabilities labeled "Probability
Fact is True" are the same for each suspect because these probabilities
depend upon the fact, not the suspect. The other probabilities,
however, depend upon the potential suspect. See Investigation.
2.4
Compare the Probability an Assertion is True
to the Standard of Proof
Evidence
can be evaluated to predict the decision of others such as attorneys,
prosecutors, judges, and jurors: Their decisions often depend upon the
standard of proof.
Criminal
Proceeding. The probability an assertion is true in a criminal proceeding should
be compared to two different standards of proof, depending upon the
stage of the proceeding:
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Accusation.
The standard of proof required for accusation is probable cause. One
of two approaches to accusation can be followed:
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Information.
The prosecutor might accuse directly. In this case, accusation
is called Information.
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Grand
Jury Indictment. The prosecutor might call a grand jury or
inquest jury. These juries might then accuse by recommending indictment.
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Prosecution.
The standard of proof required for conviction is commonly called reasonable
doubt, although its opposite, reasonable certainty, is used for comparisons.
(For example, a reasonable certainty of 85% is a reasonable doubt
of 15%.)
Civil
Proceeding. The probability an assertion is true should be compared to the
standard of proof called preponderance of evidence, a probability that
is fixed by statute at greater than 50%.
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