In Chapter 1, the term ‘critical realism’ has been introduced as an epistemological theory of knowledge employed by three scientist-theologians. Barbour, Peacocke and Polkinghorne each propose their interpretation of critical realism as a via media between the contingencies of the historical subject and a universal intelligibility of scientiﬁ c rationality. However, on the link between rationality and critical realism in theology, there are substantial differences of opinion, as we have seen. The process metaphysical theology of Barbour, the personal panentheism of Peacocke and the God of revelation presented by Polkinghorne are real differences. This diversity indicates that these three thinkers know and understand God in different ways while sharing an identical position on knowing in the sciences. Their theological claims are widely divergent. This is not to be regretted necessarily, but it reﬂ ects the need to bolster an account of just what critical realism means. In the Introduction, I mentioned the fact that critical realism has been defended by several biblical scholars such as N.T. Wright who want to raise an appreciation of scripture that qualiﬁ es as a rudimentary form of theological critical realism. These approaches are valid, but will need their own form of supplementation if we want to make claims that are more than just textually referenced. A more adequate account of critical realism could yield a common account of theological knowledge claims, just as it has for a scientiﬁ cally coherent understanding of existence. And one way to do this is to examine the rationality developed by critical realists in the scientiﬁ c ﬁ elds to see if there are clues about what can or cannot be transferred to theology.