The term ‘fact’ is a label for a model or proposition whose ideational consistency is regarded as certain by an individual or community.[1] That is, the term ‘fact’ expresses an interpersonal stance toward an ideational construal. Similarly, the expression ‘just a theory’ is a label for a model whose ideational consistency is regarded as less certain by an individual or community. The scale of certainty is a dimension within the interpersonal system of modalisation: the semantic space between ‘yes’ and ‘no’ (Halliday & Matthiessen 2004: 616-25).
On the other hand, the term ‘dogma’ is a label for a model or proposition whose ideational consistency is regarded as obligatory by an individual or community. The scale of obligation is a dimension within the interpersonal system of modulation: the semantic space between ‘do!’ and ‘don’t’ (ibid). Importantly, terms like ‘fact’, ‘only a theory’ and ‘dogma’ express a relation between a model or proposition and an individual or community.
The terms ‘subjective’ and ‘objective’ similarly express an interpersonal orientation toward metafunctional consistency. Objective and subjective are ways of presenting propositions.[2] To present a proposition as ‘objective’ or ‘value-free’ or ‘reality’ is a value-laden claim about the proposition — the subjectivity sometimes disguised by being in tune with the shared values of a community — the interpersonal function of which is to remove the negotiability of the proposition.
Footnotes:
[1] Since facts are what we are certain of, they are propositions we believe to be true.
[2] The subjective or objective orientations may be expressed explicitly or implicitly.