While there's no single person who can be definitively credited with the entire plate tectonic theory, Alfred Wegener is widely recognized as the father of the theory. He proposed the idea of continental drift in the early 20th century, which was a crucial foundation for the later development of plate tectonics.

Here's why:

* Wegener's Contribution: In 1912, Wegener published his book, "The Origin of Continents and Oceans", proposing that the continents were once joined together in a supercontinent he called Pangaea. He presented compelling evidence like the matching coastlines of continents, similar fossils found on different continents, and evidence of ancient climates suggesting that landmasses had moved over time.

* Initial Resistance: Wegener's ideas were initially met with resistance from the scientific community because he couldn't explain how continents could move across the Earth's surface.

* Building on Wegener's Work: Later scientists, including Harry Hess and Robert Dietz, who studied seafloor spreading in the mid-20th century, provided the mechanism for how continents could move. This led to the development of the plate tectonic theory which combines Wegener's concept of continental drift with the mechanism of seafloor spreading.

Therefore, although Wegener didn't have all the answers, his pioneering work laid the foundation for the plate tectonic theory.