Reduction (philosophy) - Types of Reduction

Types of Reduction

The distinction between the processes of theoretical and ontological reduction is equally important. Theoretical reduction is the process by which one theory is absorbed into another; for example, both Kepler's laws of the motion of the planets and Galileo’s theories of motion worked out for terrestrial objects are reducible to Newtonian theories of mechanics, because all the explanatory power of the former are contained within the latter. Furthermore, the reduction is considered to be beneficial because Newtonian mechanics is a more general theory — that is, it explains more events than Galileo's or Kepler's. Theoretical reduction, therefore, is the reduction of one explanation or theory to another — that is, it is the absorption of one of our ideas about a particular thing into another idea.

By contrast, ontological reduction is the process of reducing things themselves to one another. For example, it was once believed that life was an irreducible property of objects. An ontology of such properties might therefore have read:

• extension in space
• location in space
• is alive
• and so on.

All the other properties of an object, such as its shape, color, or mobility are considered to be nothing more than the effects of these irreducible properties. Shape, for example, is a function of in what way the object is extended in space, as is color, since it is determined by how light bounces off a surface, which is in turn determined by how that object is extended in space.

Science now considers that all life forms are alive by virtue of the fact that they are physically organized in such a way that they can reproduce themselves, not because they possess a special property distinct from and in addition to their physical organization. Biologists therefore say the property of life is reducible to the physical properties of an organism; being alive is simply nothing more than having certain physical properties.