Guide of the Perplexed Part II, chap 25.

The following is my formulation of what I learned in discussing this chapter with Rabbi Moshe Meiselman [I alone take responsibility for all the content].

There are rules determining when an interpretation of text is acceptable:

1. Peshat [literal, simple] interpretation is to be used, unless there is a compelling reason to reject it.
2. 2. A philosophical demonstration against [any] interpretation is a compelling reason against it. [What counts as a “philosophical demonstration” will be addressed below.]
3. That an interpretation violates central religious principles is a compelling reason against it.
4. There are absolute limits beyond which interpretation cannot pass – even in the presence of compelling reasons against an interpretation, a reinterpretation may be impossible since the reinterpretation passes those limits [See Part I chaps 1-50 and below].

There are five cases to which these principles are applied:

1. Rejecting the peshat of texts that describe G-d in corporeal terms.
2. Rejecting eternity according to Aristotle
3. Rejecting eternity according to Plato
4. The condition under which we would accept eternity according to Plato.
5. The condition under which we would accept eternity according to Aristotle

Here is how the cases come out via the principles:

1. there is a philosophical demonstration against G-d’ corporeality, so that is a compelling reason against the peshat describing G-d as corporeal [2]; the alternative interpretation does not violate religious principles [3]; the alternative interpretation is within the acceptable limits [4]
2. there is no philosophical demonstration of eternity according to Aristotle, so that is no reason reject the peshat [of creation] [1,2]; eternity according to Aristotle violates central religious principles, so that is a compelling reason not to change the peshat [3]; to change the peshat in those texts would pass beyond the acceptable limits of interpretation
3.  there is no philosophical demonstration of eternity according to Plato, so that is no reason reject the peshat [of Creation] [1,2];
4. If there were a philosophical demonstration of eternity according to Plato, there would be a compelling reason to reject the peshat of the verses of creation [1,2]; the reinterpretation would not violate any central religious principles [3]; the reinterpretation would not violate the limits on interpretation [4]
5. If there were a philosophical demonstration of eternity according to Aristotle, there would be a compelling reason to reject the peshat of the verses of creation [1,2]; but the reinterpretation would pass beyond the limits of acceptable interpretation – and then we would not reinterpret [though it is not clear what we would do]

Now here they are again, with the passages from the text inserted:

6. there is a philosophical demonstration against G-d’ corporeality, so that is a compelling reason against that peshat [2] the Incorporeality of God has been demonstrated by proof:; the alternative interpretation does not violate religious principles [3] Secondly, our belief in the Incorporeality of God is not contrary to any of the fundamental principles of our religion: it is not contrary to the words of any prophet.; the alternative interpretation is within the acceptable limits [4] nor is it impossible or difficult to find for them a suitable interpretation
7. there is no philosophical demonstration of eternity according to Aristotle, so that is no reason reject the peshat [of Creation] [1,2] But the Eternity of the Universe has not been proved; eternity according to Aristotle violates central religious principles, so that is a compelling reason not to change the peshat [3] we should necessarily be in opposition to the foundation of our religion, we should disbelieve all miracles and signs, and certainly reject all hopes and fears derived from Scripture,; to change the peshat in those texts would pass beyond the acceptable limits of interpretation unless the miracles are also explained figuratively. The Allegorists amongst the Mohammedans have done this, and have thereby arrived at absurd conclusions and But if we assume that the Universe has the present form as the result of fixed laws, there is occasion for the above questions: and these could only be answered in an objectionable way, implying denial and rejection of the Biblical texts, the correctness of which no intelligent person doubts.[4]
8.  there is no philosophical demonstration of eternity according to Plato, so that is no reason reject the peshat [of Creation] [1,2] But the Eternity of the Universe has not been proved
9. If there were a philosophical demonstration of eternity according to Plato, there would be a compelling reason to reject the peshat of the verses of creation [1,2]; the reinterpretation would not violate any central religious principles [3] If, however, we accepted the Eternity of the Universe in accordance with the second of the theories which we have expounded above (ch. xxiii.), and assumed, with Plato, that the heavens are likewise transient, we should not be in opposition to the fundamental principles of our religion: this theory would not imply the rejection of miracles, but, on the contrary, would admit them as possible.; the reinterpretation would not violate the limits on interpretation [4] We should perhaps have had an easier task in showing that the Scriptural passages referred to are in harmony with the theory of the Eternity of the Universe if we accepted the latter, than we had in explaining the anthropomorphisms in the Bible when we rejected the idea that God is corporeal.
10. If there were a philosophical demonstration of eternity according to Aristotle, there would be a compelling reason to reject the peshat of the verses of creation [1,2] If, on the other hand, Aristotle had a proof for his theory, the whole teaching of Scripture would be rejected, and we should be forced to other opinions.; but the reinterpretation would pass beyond the limits of acceptable interpretation – and then we would not reinterpret [though it is not clear what we would do]

The quotes under g clearly illustrate limits on interpretation, and this last quote is absolutely compelling: even a philosophical demonstration contradicting the whole of the content of the Torah would not lead to reinterpretation!

It remains to comment on the Rambam’s meaning for “philosophical demonstration”. It is clear from Part 2 chapter 17 that any demonstration relying of the assumption of the uniformity of the laws of nature in the past would not count. On the other hand, the Rambam’s own demonstrations start from presently observed realities and use natural physical/philosophical reasoning, so something like that would count. In any case, the age of the universe and evolution and relating theorizing clearly will not count.

Here is the whole chapter for your convenience: 

WE do not reject the Eternity of the Universe, because certain passages in Scripture confirm the Creation; for such passages are not more numerous than those in which God is represented as a corporeal being; nor is it impossible or difficult to find for them a suitable interpretation. We might have explained them in the same manner as we did in respect to the Incorporeality of God. We should perhaps have had an easier task in showing that the Scriptural passages referred to are in harmony with the theory of the Eternity of the Universe if we accepted the latter, than we had in explaining the anthropomorphisms in the Bible when we rejected the idea that God is corporeal. For two reasons, however, we have not done so, and have not accepted the Eternity of the Universe. First, the Incorporeality of God has been demonstrated by proof: those passages in the Bible, which in their literal sense contain statements that can be refuted by proof, must and can be interpreted otherwise. But the Eternity of the Universe has not been proved; a mere argument in favour of a certain theory is not sufficient reason for rejecting the literal meaning of a Biblical text, and explaining it figuratively, when the opposite theory can be supported by an equally good argument.

Secondly, our belief in the Incorporeality of God is not contrary to any of the fundamental principles of our religion: it is not contrary to the words of any prophet. Only ignorant people believe that it is contrary to the teaching of Scripture: but we have shown that this is not the case: on the contrary, Scripture teaches the Incorporeality of God. If we were to accept the Eternity of the Universe as taught by Aristotle, that everything in the Universe is the result of fixed laws, that Nature does not change, and that there is nothing supernatural, we should necessarily be in opposition to the foundation of our religion, we should disbelieve all miracles and signs, and certainly reject all hopes and fears derived from Scripture, unless the miracles are also explained figuratively. The Allegorists amongst the Mohammedans have done this, and have thereby arrived at absurd conclusions. If, however, we accepted the Eternity of the Universe in accordance with the second of the theories which we have expounded above (ch. xxiii.), and assumed, with Plato, that the heavens are likewise transient, we should not be in opposition to the fundamental principles of our religion: this theory would not imply the rejection of miracles, but, on the contrary, would admit them as possible. The Scriptural text might have been explained accordingly, and many expressions might have been found in the Bible and in other writings that would confirm and support this theory. But there is no necessity for this expedient, so long as the theory has not been proved. As there is no proof sufficient to convince us, this theory need not be taken into consideration, nor the other one: we take the text of the Bible literally, and say that it teaches us a truth which we cannot prove: and the miracles are evidence for the correctness of our view.

Accepting the Creation, we find that miracles are possible, that Revelation is possible, and that every difficulty in this question is removed. We might be asked, Why has God inspired a certain person and not another ? Why has He revealed the Law to one particular nation, and at one particular time? why has He commanded this, and forbidden that ? why has He shown through a prophet certain particular miracles ? what is the object of these laws ? and Why has He not made the commandments and the prohibitions part of our nature, if it was His object that we should live in accordance with them ? We answer to all these questions: He willed it so; or, His wisdom decided so. just as He created the world according to His will, at a certain time, in a certain form, and as we do not understand why His will or His wisdom decided upon that peculiar form, and upon that peculiar time, so we do not know why His will or wisdom determined any of the things mentioned in the preceding questions. But if we assume that the Universe has the present form as the result of fixed laws, there is occasion for the above questions: and these could only be answered in an objectionable way, implying denial and rejection of the Biblical texts, the correctness of which no intelligent person doubts. Owing to the absence of all proof, we reject the theory of the Eternity of the Universe: and it is for this very reason that the noblest minds spent and will spend their days in research. For if the Creation had been demonstrated by proof, even if only according to the Platonic hypothesis, all arguments of the philosophers against us would be of no avail. If, on the other hand, Aristotle had a proof for his theory, the whole teaching of Scripture would be rejected, and we should be forced to other opinions. I have thus shown that all depends on this question. Note it.