The phrase "a certain theory" is correct and usable in written English.
It can be used when referring to a specific theory without naming it directly, often to imply that the theory is known or relevant to the context.
Example: "In the discussion of climate change, a certain theory suggests that human activity is the primary driver of global warming."
Alternatives: "a particular theory" or "a specific theory".
Over the years, many of us have embraced a certain theory to explain men's economic decline.
Brillo Box, unlike the pile of Brillo boxes in the supermarket storeroom, is transfigured by "a certain theory of art".
If you hold a certain theory of education, that answer is not as circular as it sounds.
Such a thesis may appear as a completeness claim for a certain theory, produced as science-as-product by the inquiry.
However, if most scientists believe in a certain theory and fewer disagree, then we should not give equal weight to each viewpoint.
Some add an extra layer of projection and interpretation; they adhere to a certain theory of compatibility, rooted in psychology or brain chemistry or genetic coding, or they define themselves by other, more readily obvious indicators of similitude, such as race, religion, sexual predilection, sense of humor, or musical taste.
It also subscribes to a certain film theory that has always interested me: the Inconvenient Nazi theory.
"Normal" science consists of "puzzle-solving", finding answers to questions that remain within a certain overarching theory, or "paradigm".
It might be less polemical than it was when subscribing to a certain film theory could make you a marked man among your fellow critics.
If you are a public official or a small-town resident and you realize that some writer is preparing a narrative account of events in which you were directly involved, a certain game theory may influence your decision about whether (and how freely) to talk.
Someone who is an authority on a certain scientific theory or natural phenomenon?
