The word 'model' suggests something more than a two dimensional flat diagram. Models are used to represent exterior form, such as model airplanes, but they can also exhibit internal systems such as power stations or the human body. In the natural sciences models serve to suggest new directions for advanced research. Einstein's relativity model proved to have exciting heuristic value as it suggested hundreds of new avenues for scientific research. Modern biochemistry and genetics were triggered by the double helix model for the DNA molecule. [See James D. Watson, The Double Helix: A Personal Account of the Discovery of the Structure of DNA, New York: Atheneum, 1968.]
Obviously models are invented with some purpose in mind. And having invented one model we tend to enlarge it, and if possible connect with other models. Geometry for example began with a simple model of circles, straight lines, squares and rectangles for tomb and temple building. By adding a third dimension, and including the dimension of time, a system of astronomy and physics emerged.
In their Principia Mathematica Bertrand Russell and Alfred Whitehead demonstrated that all mathematics is a form of logic. In his Tractatus Logico-Philosophicus Ludwig Wittgenstein then showed that the sciences are logical constructs or grids by which we can picture and process whatever is out there. But beyond what we can put into language there is mystery, concerning which we should be silent. By the time he wrote his Philosophical Investigations Wittgenstein had seen that the whole of human language functions as a logical grid for picturing and processing a part of the mystery around us.
As science develops we discover that alternative models can be used to picture one area of the reality around us. Thus a particular person can be described socially, geographically, by weight and measurement, by history, economics, bone structure, physiology, or biochemistry. It has recently become theoretically possible to describe a person totally by genetic structure.
The use of alternative models in theology is a comparatively recent development. The tradition had been that a theologian should know the truth and demonstrate the falsity of all other pretensions. The impending importance of the linguistic revolution for the social sciences was seen by Peter Winch, The Idea of a Social Science, London: Routledge & Kegan Paul, 1958. He was one of the circle of those who had been influenced by Ludwig Wittgenstein, though the Philosophical Investigations were not actually published until 1967.
The implications for theology were pointed out by Frederick Ferre, Language, Logic and God, New York: Harper & Row, 1961. Ferre's title was obviously chosen to indicate it was the opening of the theological assault on the Logical Positivism of Alfred J. Ayer's Language, Truth and Logic, 1936.
The next year in The Structure of Scientific Revolutions, 1962 Thomas S. Kuhn argued that the great steps forward, or revolutions, in the progress of science are by way of paradigm shifts rather than by the mere accumulation of information. He stressed that paradigms in themselves can never be right or wrong. They are merely invented logical structures.
When a new model is invented and offered to us we can evaluate it for elegance, explanatory power, and usefulness. A flat earth model for example is not wrong and it works very well for surveying, or even to picture a smaller country. A globe is a better model for air navigation. Newton's model of the solar system was very elegant, but it won't do for flying to Venus. For that you need Einstein's relativity. [The discussion has been immense, see Gary Gutting (Ed.), Paradigms and Revolutions: Applications and Appraisals of Thomas Kuhn's Philosophy of Science, Notre Dame: University of Notre Dame Press, 1980.]
An early attempt at model theology was Avery Dulles, Models of the Church, Doubleday, 1974. Robert Brow used a model theology method in Go Make Learners: A New Model for Discipleship in the Church, Wheaton, Illinois: Harold Shaw, 1981. Sally McFague developed many of the categories needed for model theology in Metaphorical Theology: Models of God in Religious Language, Philadelphia:Fortress Press, 1982, and then applied them in Models of God: Theology for an Ecological, Nuclear Age, Philadelphia: Fortress Press, 1987.
The importance of paradigms in modern theology is indicated by Hans Kung and David Tracy, Paradigm Change in Theology: a Symposium for the Future, New York: Crossroads, 1989. Kung correctly identified some implications of Kuhn's work in the first chapter, but by the end of the symposium Kung is unfortunately still looking for the correct new paradigm for theology (pp.439, 443, 449, 451). As we demonstrate in chapter 2 and chapter 3 model theology can observe and classify many different models of religion and ideology. There is no such thing as a correct model in the sciences or in theology. We can only choose between alternative models in the light of what we want to do. In chapter 7 and chapter 8 we see on what basis the commitment to one particular model can be made.
Kuhn used the term paradigm, which I have avoided in this book in favour of the simpler word model. Nothing hangs on the dividing line between models and paradigms. See Frederick Ferre, "Mapping the Logic of Models in Science and Theology" in Dallas M. High (Ed.), New Essays in Religious Language, New York: Oxford University Press, 1969.
Margaret Masterman showed that Kuhn was working with at least three quite different kinds of paradigm. She called them metaphysical, sociological, and construct paradigms. [ "The Nature of a Paradigm," in I.Latakos and A.Musgrave, Criticism and the Growth of Knowledge, Cambridge University Press, 1970.]
Masterman's metaphysical paradigms are large scale world views. So in chapter 2 and chapter 3 we worked at twenty four species of religion or ideology as alternative world view or metaphysical paradigms. Masterman's sociological paradigms picture the stated and unstated rules for say a local community, or a group of scientists, or a church denomination. In chapter 5 I outline some models of Baptism and the New Birth as sociological paradigms ("this is the way we do it") within the larger metaphysical models of Christian Theism.
Construct paradigms in Margaret Masterman's terminology are used to explain the working of one component of a bigger paradigm. For example the double helix pictures the structure of the DNA molecule as a key component in the bigger paradigm of biochemistry. By way of example I note different constructs for words like sin, judge and hell which form part of bigger theistic models. [See Anthony C. Thiselton, "Polymorphous Concepts" in The Two Horizons: New Testament Hermeneutics and Philosophical Description, London: 1980, Grand Rapids: William B.Eerdmans, 1980, pp.407-427.]