The principle of authority does not suffice to eliminate uncertainty i
n the execution of contracts. To reduce the margin of uncertainty, the
parties to a contract appeal to the need for mutual trust. After anal
yzing how various scholars have dealt with this notion of mutual trust
, the author uses actual observations to point out the ''signals'', wh
ether visible or not, in which a trustful relationship can be grounded
. These signals may have to do with personal relationships or with pro
fessional norms of cooperation.