For starters, distinguish what is a disciplinary ruling and what is not.
It is assumed too often that anything and everything said in an Encyclical is doctrinal. That is simply not the case. Some of what is said is doctrinal; some is how we are to respond to the doctrine which may be laid out in the encyclical. As to the response, that may or may not be time conditioned; that is, it is how the church at that time in history sees that the faithful need to respond to the doctrinal postion.
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