How strong is the association of this field with the class "low erosion"?

A chain is as strong as its weakest link!

The field in this examples runs low risk of erosion with confidence 30%! We say that its membership to the class "low risk" of soil erosion is 0.3.

This is an example of conjunctive reasoning: Many different conditions have to be fulfilled simultaneously for something to happen. The confidence with which this "something" will happen is equal to the smallest of the confidences with which the necessary conditions are fulfilled.

What happens when many routes lead to the same conclusion?