There happens to be a pattern where a discussant makes a statement about the world and his/her partner retorts with another statement or usually a question that translates the subject onto a trajectory where the statement of the first discussant--his or her argument core--becomes seemingly irrelevant or appears nonsensical or ultimately indefensible or is otherwise severely crippled in the newly introduced context. It is not the case that the first statement is indeed erroneous or otherwise lacking; only the perception of it as expressed in the retort makes such claims, implicitly or otherwise.
I am interested in situations where this shift in context or focus can be attributed to reasons having to do with the argument itself, for example, as it is understood by the discussants and the trajectory of the discussion itself. I am not interested in straw-man arguments or other devices that aim for anything other than clarifying the subject of the discussion.
Is this pattern identifiable and does it have a name?