What word describes something that frequently switches between opposite states or views?

I have been searching for a word, which I'm beginning to doubt exists at all, that describes a person or thing that changes from one state to the opposite of that state frequently, i.e. an adjective describing the binary oscillation of some particular state.

Words like mercurial or capricious are similar but they only indicate that something changes in general, not necessarily to its opposite. I'm looking for something that indicates an antipodal change.

The closest word I have found is bipolar but, as this refers primarily to a mental disorder, I feel its application to things like the weather or someone's cooking is too poetic. I want a word that is more literal.

Oddly, and with great frustration, I find that while the definition of bipolar is something like "having or relating to two poles or extremities", which specifically implies opposition, all of the synonyms I find for "bipolar" are only describing a general tendency to change.

_____________ - a person or thing that frequently switches between opposite states or dispositions

Solution 1:

Bipolar seems to best suggest switching between extremes along the same line or element, the association with mental illness is a consequence of the word bipolar being a good fit because depression and mania are considered polar to each other, like north and south poles in the axis of the earth, etc. Common usage like applying it to mental health does not eliminate the function of the base word, no more than than the issue of being gay has taken on additional meaning over time.

Solution 2:

A vacillator, perhaps?

Vacillate: Waver between different opinions or actions

They view him as a vacillator whose tactical shifts in the face of foreign pressure have been unpardonable. _(Oxford)

Unlike mercurial or capricious, vacillator has a back-and-forth implication. Maybe not exactly opposite ends, but it does imply that the vacillator tends to switch their opinion, rather than simply change it to anything.