New law school students are quickly taught that the text of a document controls when it is clear, and that the remainder of the document and its historical background can be used to establish intent when it is not. This approach works perfectly well with contracts and statutes. Does it make sense as applied to the Constitution?
As far as it goes, absolutely. The problem is that a 200+ year old document with lots of very general language is rarely clear, and that establishing intent through historical research, if done honestly and correctly, is an extremely complex task. As a result, some other source must be used to fill in the gaps in the record.
Thomas gets over this hurdle by cherry-picking history in an unprincipled way in order to get the reactionary outcome he desires. Alito, for his part, apparently gives indications in his new book that he will be using “common good constitutionalism” to fill in the gaps in the historical record. That means medieval Catholic theologians whose influence on the drafting of the Constitution was minimal will be playing a large role in his jurisprudence for the foreseeable future.
Right-leaning lawyers have complained that the Warren Court simply made up new constitutional rights in order to further the ideology of a majority of the justices for decades. The New Right is turning originalism into a Trojan Horse to do the exact same thing in the opposite direction.