I first came to know about the 1995 shift in the definition of a generation from this website, having not stepped foot into a KH, bar the odd funeral, since the early 90s.
I recently had the opportunity to question my mother and aunt about the change in doctrine. In an apparently innocent way, I asked about the post Great War generation dying out and what that meant for the prophecy. As you'd expect, I was told that the generation was never meant to be taken literally. I said that it was certainly taken literally when I attended meetings.
To prove me wrong, my aunt sent me a cut and paste from a 1984 Watchtower (below in part). This is the first pre-1995 reference to the ambiguity of a generation that I've seen (although the same historian was quoted in 1995 again). Did everyone else miss this decade-earlier revelation as well?
w84 5/15 pp. 4-7 1914—The Generation That Will Not Pass Away
"THIS generation will by no means pass away until all these things occur," said Jesus. (Matthew 24:34) But what is meant by the word "generation"?
In his book The Generation of 1914, professor of history Robert Wohl presents an unusual definition when he states: "A historical generation is not defined by its chronological limits or its borders. It is not a zone of dates . . . It is more like a magnetic field at the center of which lies an experience or a series of experiences. . . . What is essential to the formation of a generational consciousness is some common frame of reference that provides a sense of rupture with the past . . . This frame of reference is always derived from great historical events like wars, revolutions, plagues, famines, and economic crises."
From that point of view, the Great War of 1914-18 and its aftermath certainly formed a "frame of reference" to mark a generation. As professor Wohl comments: World War I created "an overwhelming sense of rupture with the past. Those who lived through the war could never rid themselves of the belief that one world had ended and another begun in August 1914."
Jesus used the word "generation" many times in different settings and with various meanings. But what did he mean when he spoke of a ‘generation that would not pass away’? Some have interpreted "generation" to mean a period of 30, 40, 70 or even 120 years. However, a generation is really related to people and events, rather than to a fixed number of years.