The most apparent contradiction is that if Fagan were correct, most human societies today would still be hunter-gatherer. But they are not.
The point the author doesn't notice is that 'hunter-gatherer' and 'farming' refers to societies, not individuals: a subsistence farmer in drought conditions may be more vulnerable than a given member of a hunter-gatherer society to drought, since the latter can just move without abandoning an expensive investment in cleared land, irrigation works, and livestock. But those investments mean the farming society recovers more quickly and (above all) is more powerful when fighting hunter-gatherers who can simply be swamped by greater numbers.
The most apparent contradiction is that if Fagan were correct, most human societies today would still be hunter-gatherer. But they are not.Farming started when hunter-gatherers domesticated plants and animals, proving it all-round more profitible to bring the food to you than you to the food. That's the inherent quality of civilization.
His California archaeology book is a good example. That's a subject I know well. I got 20 pages and had to stop.
The book was remaindered out within a year.