The phrase "contextually determined" is correct and can be used in written English.
You can use the phrase to describe how the meaning of something is determined by its context. For example: "The meaning of the proverb is contextually determined, based on the situation in which it is being used."
The allophones of a phoneme, then, are its contextually determined variants and they are in complementary distribution.
Philosophers such as Peter Achinstein and Bas van Fraassen offered pragmatic theories, according to which what counts as an explanation is contextually determined.
The best science book I read was Adam Alter's "Drunk Tank Pink," which is a really provocative look at how much our behavior is contextually determined.
On the other hand, measure words can be contextually determined as minimal atomic units.
Such points would be flexibly interpreted not as unchangeable levels but rather as historical (contextually determined) phenomena.
Rather, an explanation is just a description of reality that serves a contextually determined purpose, namely that of answering a why-question.
Conservation efforts should recognize that forest degradation and deforestation are contextually specific, determined mostly by people's efforts to maintain their basic livelihood, and therefore necessitate local-scale interventions that feed into landscape-scale policy initiatives.
Granted that [p] and [ph] are variants of the same phoneme /p/, it can be said that they are contextually, or positionally, determined variants of it.
Relevance is determined contextually by the possibility of there being a coherent account of how those categories came to be defined.
Latent Semantic Analysis is a technique to transform qualitative data into quantitative information, but it has limitations, including situations where meaning is determined contextually.
LSA can evaluate a word whose meaning is determined contextually (e.g., "we moved back," is differentiated from "hurt my back").
