Liberal political vocabulary

Liberal political vocabulary frequently presents its own values as if they were universally neutral or self-evidently desirable, thereby making ideological commitments appear objective.

That is a coherent research hypothesis.

But notice it is different from saying:

Therefore liberty, freedom, or rule of law have no independent meaning.

The first concerns historical and political uses of language.

The second concerns the concepts themselves.

Those are different claims and require different kinds of evidence.