Description Syllabus Notes Assignments Homework Research

Evidence (Grounds) 

Evidence is

  • External to advocate / objective    AND

  • Has probative force (or value) = believability + relevance


1.    Factual evidence

A.   Reports (examples and descriptions)

  • Reports are most effective if specific and highly relevant to claim

  • Evaluation of reports (Challenge report evidence on ...)

1.                  recency

2.                  sufficiency

3.                  relevance

4.                  representativeness

5.                  consistency with audience exper.ience & other known facts

6.                  quality of source characteristics including: is the source:

  •  in a position to observe?

  •  capable of accuracy?

  •  not prejudiced?

  •  has a truthful reputation?


 B.     Statistics (quantitative data groupings and summaries)

  • Statistics are most effective if how they are collected is explained

  •  Evaluation of statistics (Challenge statistical evidence on ...)

1.                  are the statistics recent?

2.                  are terms clearly defined?

3.                  is sampling correct?

4.                  Are measures of reliability, validity, & error included.

5.                  is something omitted (e.g. control groups, ) (e.g. baseline Athe rate tripled@ [from 2 in a trillion to 6 ... ]


2.     Opinion - interpretation of facts, judgments -- expert and lay


a.                  establish causal connections in the case (inherency and benefits)

b.                  future prediction (benefits)

c.                  propose workable solutions (solvency) (benefits)

  • Evaluation of opinion evidence (Challenge opinion evidence on ...)

1.                  is the source qualified?

2.                  biased?

3.                  respected by others in field?

4.                  is opinion internally consistent?

5.                  has the source used data - externally consistent with facts?



3.  Analogy -  things compared to make an inference from one to the other

  •           evaluation of analogies:  (Challenge analogies on ...)

Are the things compared similar in all important ways?



Last updated 10/14/2008