Jürgen Habermas is a wide-ranging thinker whose ideas have formed the philosophic foundation of critical systems thinking (CST). But can the Critical approach incorporate ideas from other thinkers without abandoning its Habermasian roots? The danger of adding ideas piecemeal to address specific difficulties in CST is that the whole will eventually collapse because of inconsistencies. So if we wish to import ideas from other thinkers we need to understand the points of agreement and disagreement with critical theory. This requires reference to a set of criteria, though not necessarily in any rigid way. This paper applies a set of criteria to a philosophic framework of ideas (that of the Dutch philosopher Herman Dooyeweerd) in order not to 'score' the ideas for Criticality, but rather to understand the process of bringing the ideas of a thinker from a different tradition to bear on the Critical approach in a commensurable way.