open question

noun

1. a matter which is undecided
2. a question that cannot be answered with a yes or no but requires a developed answer

An unresolved issue, one that has not been finally determined. For example, Whether the town should pave all the unpaved roads remains an open question. In the mid-1800s this term acquired a specific meaning in the British Parliament, that is, “an issue on which members may vote independently, without respect to their party affiliation.”