Aging and oxidative stress are complex phenomena, and their understanding is of enormous theoretical and practical significance. Numerous hypotheses and theories that attempt to explain these phenomena have been developed. These hypotheses and theories compete with each other, with each claiming to be the correct one, while significantly contradicting each other. It is important to develop a maximally correct theory that may then trigger significant practical breakthroughs. None of these theories is entirely correct or close enough to the truth. However, most of them contain many correct elements (CE). Finding these CE is possible by analysis of these theories. Once the CE are found, they can be merged by synthesis in a better new theory. An analysis of some of the theories of aging followed by synthesis is attempted.