Question

哪位熟悉新概念英语第四册的英语高手能告诉我第44课Patterns of Culture 的最后一段为什么用过去时态？

这是一篇议论文，前边基本上都是议论社会风俗研究的问题，以一般现在时为主，为什么这最后一段用了过去时态？附最后一段的原文如下：
Anthropology was by definition impossible, as long as these distinctions
between ourselves and the primitive, ourselves and the barbarian, ourselves and the
pagan, held sway over people's minds. It was necessary first to arrive at that
degree of sophistication where we no longer set our own belief against our
neighbour's superstition. It was necessary to recognize that these institutions which
are based on the same premises, let us say the supernatural, must be considered
together, our own among the rest.

Answer 1

我觉得可能是因为，这篇文章是节选自一本书，书名就叫patterns of culture. 最后一段的时态跟这段节选所在的上下文有关。
另外一种解释是，文中前三段是客观陈述，用一般时态，最后一段是作者的主观结论，为了显得谦逊，作者采用了委婉语气的过去时态。
个人观点，不当之处欢迎批评讨论。

Answer 2

引发读者想象