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aware that the value of the diamond on the open market is only $1000. But this
diamond belonged to Adam’s great grandmother and because of sentimental
attachment, Adam valued the diamond more highly than other diamonds. An evaluative
component is always necessary in order to reach a decision.
Situation or question
Value Evidence Value Evidence Value Evidence Value Evidence Value
Decision outcome
Figure 1. The value + evidence model of reasoning.
As this visual representation demonstrates, human reasoning is a complex combination
of values and evidence.
What is the fact / value distinction?
So how is the distinction made between what is fact and what is value? For example,
how do I know that ‘this is a diamond’? This question has been the concern of
philosophers for centuries. For this thesis, I take what might be termed a common sense
view of evidence. This is a table, this is a computer and this is a desk. The sun will rise
tomorrow morning. This is evidence which exists independently of my human
engagement. Williams (cited O’Grady, 2002) couches the answer in terms of
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