DiLorenzo’s Ph.D. is in economics. Some economists view everything through the lens of economics and don’t see other motivations to political activity. Economists also group in schools (like fish), and different schools have different blind spots.
One of DiLorenzo’s blind spots is not seeing that slavery was a more important issue (even a more important economic issue) than tariffs. He has other blind spots as well. It’s up to the rest of us to bring together what we do know to try to see the whole picture.
So what prompted the secession crises of 1828?
Was slavery the core reason why the Southern states wanted to leave in 1828? What was the core reason?
Correct. His degree was in economics, but that does not mean he lacked the academic training for accurate research and documentation. My point is that having a PhD certainly reflects some intellect and accomplishment qualifications.
I'm not sure you read the book. I did, and I don't recall seeing a slant toward economics at all. His book was a) about Lincoln and b) to a lesser extent what led up to the war.
One of DiLorenzo’s blind spots is not seeing that slavery was a more important issue (even a more important economic issue) than tariffs.
That's a debatable topic and not a blind spot. The reasons for the war is the topic of many books. You may have the opinion that slavery was the primary motivator -- I disagree with your opinion as do many others.
Reports indicate that about 5% of the population of the south owned slaves. Or in other words 95% of the population DID NOT own slaves. There were many causes to the war to those 95%.
A big part of it was "states rights" vs federal rights. The states in the South were losing their rights, and they wanted a divorce. That's the bottom line. Was slavery an issue? Yes. But it was not the predominant issue for 95% of the population.