It doesn’t give you all the information you need, but that’s how the problem was originally tackled. Scientists noticed that they had two contradictory models for light, which had a few overlapping characteristics. Those overlapping areas allowed them to start formulating new theories. Of course it took ridiculous amounts of work after that to figure out a reasonable approximation of reality, but one has to start somewhere.
It doesn’t give you all the information you need, but that’s how the problem was originally tackled. Scientists noticed that they had two contradictory models for light, which had a few overlapping characteristics. Those overlapping areas allowed them to start formulating new theories. Of course it took ridiculous amounts of work after that to figure out a reasonable approximation of reality, but one has to start somewhere.