The Negative Side: Lack of Trust, Implicit Trust, Mistrust, Doubts and Diffidence - Trust Theory: A Socio-Cognitive and Computational Model - page 119

In a sense 'by-default' trust is another form of 'conditional' trust. It is a belief of trustwor-
thiness relative to another belief:

IF& UNTIL ( Not ( Bel X ( Not ( Trustworthy Y )) → Bel X ( Trustworthy Y ) (4.4)

where means 'implies'.

Or it is some sort of conditional rule about the trust act:

→

IF& UNTIL ( Not ( Bel X ( Not ( Trustworthy Y )) ⇒ Trust ( XY ) (4.5)

where means 'produces'.

This means that X will control the validity of her assumption; and its confirmation.
Of course, this default rule is very different (in feeling and behavior) from the possible
opposite one; some sort of conditional distrust :

⇒

IF& UNTIL ( Bel X ( Trustworthy Y )) → Not ( Trust ( XY )) (4.6)

4.7 Insufficient Trust
Trust insufficiency is when the trust that X nevertheless has in Y does not exceed the threshold
(adopted by X in that context for that task) necessary for the decision to delegate, entrust Y .
Notice that:

The amount of trust can be even greater than the amount of distrust or of lack of trust; but,
nevertheless, insufficient (see Figure 4.3).
when trust is not sufficient, lack of trust is too much, but it is not necessarily all 'distrust':
there can be a lot of ignorance or doubt (see below).

While introducing more sophisticated and quantitative models, we get other notions that are
very interesting, like 'evidence/reason-based' trust/distrust versus trust/distrust just based on
giving/not-giving credit.
There is another form of trust 'insufficiency': a relative not an absolute one.
Negative evaluations can in fact be 'absolute' or 'comparative' and 'relative' to a standard,
threshold, etc. (Chapter 2 and 3). If the evaluation of Y is 'inferior' to the needed threshold
or standard, or inferior to the evaluation of Z , it becomes 'negative' ( Y is insufficient, is
inferior). In a sense here we are at a meta-evaluative level; there is a sort of meta-evaluation:
an evaluation of the evaluation: ' Is this evaluation sufficient?' ' No; it is not a really good
evaluation '. In particular, it is not really a 'lack of trust' a trust which is or would be 'enough'

Threshold: 75%

Trust (65%)

Lack of Trust (35%)

Figure 4.3 For the Delegation, Trust must be over the threshold