Lawyer: A body of circumstantial evidence is like a rope, and each item of evidence is like a strand of that rope  Just as additional pieces of circumstantial evidence strengthen the body of evidence, adding strands to the rope strengthens the rope  And if one strand breaks, the rope is not broken nor is its strength much diminished
Thus, even if a few items of a body of circumstantial evidence are discredited, the overall body of evidence retains its basic strength
presumes, without providing justification, that the strength of a body of evidence is less than the sum of the strengths of the parts of that body