That is the stock, canned, straight from the publications answer. What they all fail to recognize is the Scripture they base doctrinal "new light" on doesn't mention "new" light at all and has nothing whatsoever to do with organizational progress in understanding.
Proverbs 4:14-19 — Into the path of the wicked ones do not enter, and do not walk straight on into the way of the bad ones. Shun it, do not pass along by it; turn aside from it, and pass along. For they do not sleep unless they do badness, and their sleep has been snatched away unless they cause someone to stumble. For they have fed themselves with the bread of wickedness, and the wine of acts of violence is what they drink. But the path of the righteous ones is like the bright light that is getting lighter and lighter until the day is firmly established. The way of the wicked ones is like the gloom; they have not known at what they keep stumbling.
This is what the paragraph reads like in the NWT without those confusing verse numbers preventing examination of the context. An individual is being instructed: "Do not do this, do that instead." This isn't prophetic instruction directed toward an organization, or a prophetic proclamation about how to identify God's organization. This is comparing one life course to another life course.
It metaphorical, but not prophetic. They have ONE verse in the entire Bible that they use to explain the "light" doctrine and, in context, it demonstrably does not do so. On the other hand, there are MANY verses that indicate the gospel would not change. One paragraph from the NT leaps readily to mind:
Galatians 1:6-9 — I marvel that YOU are being so quickly removed from the One who called YOU with Christ’s undeserved kindness over to another sort of good news. But it is not another; only there are certain ones who are causing YOU trouble and wanting to pervert the good news about the Christ. However, even if we or an angel out of heaven were to declare to YOU as good news something beyond what we declared to YOU as good news, let him be accursed. As we have said above, I also now say again, Whoever it is that is declaring to YOU as good news something beyond what YOU accepted, let him be accursed.
This flies directly in the face of their "new light" doctrine. Check out the elipses in the most recent study article that used these verses:
*** w88 5/1 p. 12 par. 11 The Challenge of Following in His Footsteps ***11 Because of this very real danger, Paul felt compelled to warn his brothers in the early Christian congregation: “I marvel that you are being so quickly removed from the One who called you with Christ’s undeserved kindness over to another sort of good news. . . . There are certain ones who are causing you trouble and wanting to pervert the good news about the Christ. . . . Whoever it is that is declaring to you as good news something beyond what you accepted, let him be accursed.” (Galatians 1:6-9) In keeping with Paul’s example, the Governing Body of Jehovah’s Witnesses today warns us of apostates and false brothers who lay down, as it were, counterfeit footprints. True Christians do not want to deviate from the path Christ has set before them at God’s direction.—Psalm 44:18.
What faithful JW ever looks up and reads partially quoted Scriptures? I know we never did, as a family. However, the WTS successfully hid the fact that Galatians says that even if Paul and the other apostles, or an angel out of heaven came with a different gospel that such a declarer would be accursed. Paul directly said that even if his footprints deviated from the gospel as the Galatians received it, he would be accursed.
What sophistry. They are filthy in their deceit.