In logical form

I am arguing something like:

1. Colonial powers frequently justified empire using words such as "civilization," "freedom," and "rule of law."  (historical claim)
2. Therefore these terms can function rhetorically to legitimize power. (supported inference if evidenced)
3. Therefore these concepts are nothing more than propaganda.  (this does not automatically follow)

Why not?

Because the same concept can be:

• sincerely held by some people,
• strategically used by others,
• partially realized in some contexts,
• violated in other contexts.

That is why historians and political theorists usually distinguish between a concept's meaning and its political use. Doing so allows them to criticize hypocrisy or manipulation without assuming that every use of the concept is insincere.