The Truth must be defined.
Here is my definition of the Watchtower Society's TRUTH:
Makeshift explanations of eventually discarded opinions.
How else do we explain the necessity of discarding what has been revealed?
If God is eternal and it is God channeling this deteriorating "Truth" something is awry!
The Watchtower Society grasps at understanding from a certain point of view.
Their conjectures, opinions and guesses become legitimate only by INSISTING they are not conjectures, opinions and guesses.
Yet, when these Truths are changed, what better proof of the fragile and unsubstantial nature is more evident?
Is there no difference at all between "ever-changing" and "eternal"?
Man's investigations are progressive because humans start from a state of ignorance.
Why would God's starting point be the same and needing "progress"?
If you have two carpenters and one of them has to tear down what he builds in order to modify his work
while the other carpenter gets it right the first time: WHO is the Master Carpenter and who is the Amateur?
What if the amateur carpenter proudly exclaims "I am a progressive carpenter". Does that change the flaws, cost-over runs and rickety construction?