How is plate tectonics a theory?

Plate tectonics theorizes that convection currents in the mantle cause large segments of the earth to move. As it is impossible presently to test the presence of the convection current in the mantle this part of plate tectonics will remain a theory.

Plate Tectonics explains many things on the earth. It explains the presence of subduction zones off the coast of South America and other places. It explains the locations of earthquakes and volcanos as well as mountain changes. Good theories are able to explain multiple observations.

Plate tectonics also makes predictions that have come true. Good theories make predictions that can be tested. Plate Tectonics predicted that the rift valleys would be expanding. Testing in the rift valley of East Africa confirmed predictions of the Plate Tectonics of spreading at diverging boundaries.

Plate Tectonics makes good explanations about why and how earth features are created. Plate Tectonics like all good theories makes good predictions. Plate Tectonics is a theory because it explains why things happen.