Who in the nineteenth century used the words ""We the people"" from the Constitution to claim that the southern states could not secede from the Union?

Abraham Lincoln, 16th president of the united states has used these words that " We the people" from the constitution to claim that the southern states could not secede from the union? He was against the secession and considered it unlawful.

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.