"The Designs of Science," is an expansion of his article in the New York Times of last July. At the end, he comments,
The modern world needs badly to hear this message. What frequently passes for modern "science” with its heavy accretion of materialism and positivism is simply wrong about nature in fundamental ways. Modern science is often, in the words of my essay, "ideology, not science". The problems caused by positivism are especially acute in the broad anti-teleological implications drawn from Darwin's theory of evolution, which has become (in the phrase of Pope Benedict XVI, writing some years ago) the new first philosophy of the modern world, a total and foundational description of reality that goes far beyond a proper grounding in the descriptive and reductive science on which it is based.
It should be noted, of course, that one need not appeal to purpose, teleology or final cause in order to do scientific research. For example, one need not say that a cat has sharp teeth so that it can tear the flesh of its prey. Rather, it is enough to simply observe that sharp teeth are an aid to tearing the flesh of its prey, and that this gives it an advantage in survival over competing carnivores. The distinction is between a relative function and a "design." It's a distinction that most neo-Darwinians consider critical to make.
The difficulty of this is not that it impedes science to reject teleology. Rather, the problem is that rejecting teleology ultimately renders moral philosophy impotent. Furthermore, most neo-Darwinians would insist that teleology is, in the words of Pierre Simone de LaPlace, an hypothesis for which there is no need. Taken literally, that judgment is a teleological one, and is therefore suspect due to self-referencing problems. If the judgment is relaxed, slightly, and taken to be only functionally relative, then there is no reason to reject an alternative philosophy that includes teleology, only a claim that there exists a philosophy that does not require it. That philosophy is called positivism. That some form of positivism is probably sufficient as a ground for the scientific method I am quite prepared to grant. That it is sufficient as a ground for social engineering, or any kind of engineering for that matter, is obviously false. All engineering involves designing something for a specific purpose, or teleology.
Morality, in its most fundamental form, must also take account of teleology. When it comes to biological systems, like the human organism, one must attempt to discern a teleology imposed by God in order to learn anything that can be learned about proper behavior. To dispose of teleology as an admissible category is ultimately to dispose of all notions of proper behavior.
This does not mean that all morality must follow from deductions from revelation. According to Cardinal Schoenborn,
Barrâ's essay addresses at some length the question of design in biology, but does not clearly affirm that reason can grasp the reality of design without the aid of faith. If my reading is correct (and I hope I am wrong), in that respect Barr has followed the overwhelming trend of Catholic commentators on the question of neo-Darwinian evolution, who gladly discuss its compatibility with the truths of faith but seldom bother to discuss whether and how it is compatible with the truths of reason.
I claim that there is indeed some level of knowledge possible from entirely empirical induction, provided only that one sees purpose in the existence of primary phenomena. But that is an area beyond the purpose of this short note.