Kalamas, when you yourselves know: "These things are bad; these things are blamable; these things are censured by the wise; ...
Kalamas, when you yourselves know: 'These things are good; these things are not blamable; these things are praised by the wise; undertaken and observed, these things lead to benefit and happiness,'
It can bee seen that actually "knowing" is presupposed: "knowing" what to abandon and what to untertake and knowing to discern the "wise" and the "unwise".
One of many example's of an advice refering the subject to itself. That whould be a blind alley if concrete instructions would not follow about what "The disciple of the Noble Ones" abandon and what they undertake.