What done4good said.
Because Watchtower is an ideology and not a method then its conclusions are predicable based on whatever is its current ideological preference, which changes.
Because science is a method then its conclusions are predictable based on that method, which does not change.
More than than an ideology, I think the best predictor for Watchtower tripe is based on a business model. In the end this means Watchtower conclusions are predictable based on whatever best promotes its religion business. From a scientific perspective this gets a little frustrating to fathom until you realize that the religion business is heavily influenced by sociological factors one of which suggests that tension (beliefs that set a religion apart as different, and strictness of those beliefs) promotes growth in a new religious movement, which Watchtower is. (Watchtower is an infant by comparison with other dominate religious institutions). This need for tension to grow a religion business ends up with an institution promoting and enforcing tenets that have no rational basis. So we end up with a religion business growing itself on the heals of fact and logic defying doctrinal positions that are only changed when it suits the business need and regardless of what facts and good reasoning point to.