Model-dependent realism

Model-dependent realism is a controversial philosophical approach to scientific inquiry, which accepts that reality can always be interpreted in a number of different ways, and focuses on how well our models of phenomena are. It claims that it is meaningless to talk about the "true reality" of the model as we can never be absolutely certain of anything (see solipsism). The only meaningful thing is the usefulness of the model. The term itself was coined by Stephen Hawking and Leonard Mlodinow in their 2010 book, The Grand Design.

Model-dependent realism asserts that all we can know about "reality" consists of networks of world pictures that explain observations by connecting them by rules to concepts defined in models.

A world picture consists of the combination of a set of observations accompanied by a conceptual model and by rules connecting the model concepts to the observations. Different world pictures that describe particular data equally well all have equal claims to be valid. There is no requirement that a world picture be unique, or even that the data selected include all available observations. The universe of all observations possibly may be covered by a network of overlapping world pictures and, where overlap occurs; multiple, equally valid, world pictures exist.

As a philosophical position, model-dependent realism is similar to Constructivist epistemology.

It is not a strict form of metaphysical realism (the world is as it is, independently of how humans take it to be), and contains features of the anti-realist position that the world is mind-dependent. Like some anti-realist positions, model-dependent realism accepts conceptual relativism, the view that having multiple world-pictures that include the same observations is not a difficulty. However, the notion that the "world is as it is, independently of how humans take it to be" is not abandoned explicitly, but replaced by the notion that whatever the world may be, all we can know of it is conceptually relative, a network of overlapping world pictures.

Introduction

This approach is explained in the following quotes from the book "The Grand Design":

"[Model-dependent realism] is based on the idea that our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth."

"There is no picture- or theory-independent concept of reality. Instead we will adopt a view that we will call model-dependent realism: the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations. This provides a framework with which to interpret modern science."

"According to model-dependent realism, it is pointless to ask whether a model is real, only whether it agrees with observation. If there are two models that both agree with observation ... then one cannot say that one is more real than another. One can use whichever model is more convenient in the situation under consideration."

"It might be that to describe the universe, we have to employ different theories in different situations. Each theory may have its own version of reality, but according to model-dependent realism, that is acceptable so long as the theories agree in their predictions whenever they overlap, that is, whenever they can both be applied."

"According to the idea of model-dependent realism ..., our brains interpret the input from our sensory organs by making a model of the outside world. We form mental concepts of our home, trees, other people, the electricity that flows from wall sockets, atoms, molecules, and other universes. These mental concepts are the only reality we can know. There is no model-independent test of reality. It follows that a well-constructed model creates a reality of its own."

In other words, our model is only as good as our ability to observe events. This is an extension of one of the basic organising principles of the instrumentalist approach to modern science, that a model is only as good as its ability to predict events. Hawking associated himself with the commonly assumed principle of 'model dependent realism' by giving it that name.

See also

• Constructivist epistemology
• Instrumentalism
• Philosophical realism
• Scientific realism

External links

• Edwards, Chris. Stephen Hawking's other controversial theory: Model Dependent Realism in The Grand Design (Critical essay), Skeptic (Altadena, CA), March 22, 2011