 In some cases, a deduction contains idle elements. For example, in an argument of the form ‘All \(A\) are \(C\), All \(B\) are \(C\), All \(C\) are \(D\), therefore All \(A\) are \(D\)’, the second premise can be omitted without destroying the relation of deducibility. Similarly in an argument of the form ‘Anything that is either \(A\) or \(B\) is \(C\), All \(C\) are \(D\), therefore All \(A\) are \(D\)’, we could get by with a simpler premise of the form ‘Anything that is \(A\) is \(C\)’ instead of the first premise. Seeing this, Bolzano sought a narrower notion that would filter out redundant or trivial inferences.