David Greenberg neatly summed some of the methodological problems with non-professional historians (as he put is "Barnes & Noble historians) writing for a mass market in a History News Network/Slate piece and is worth quoting at length:

The major failing of much popular history is that it betrays no interest in making intellectual contributions to our understanding of an issue. The Barnes & Noble historian seems to treat history as a pageant of larger-than-life events and people to be marveled at, rather than a set of social, political, and cultural problems to engage. Unless you wrestle with the ways in which the problems of the past have been defined, interpreted, ignored, or mischaracterized by other historians—the historiography—your writing will seem unsophisticated. You won't know which of your ideas are novel or trite, simple or complex, suspiciously trendy or embarrassingly out of date, or what avenues of research have already been pursued. Historians have to try to build upon what's been written, while keeping in mind that the goal is broader than just revising or applying other scholars' findings.

This light engagement with method is part of the reason why works by Isaacson or David McCullough are often so grating to specialists; it is not that the overall facts are wrong, it is that their interpretations of the past are often incredibly simplistic. In a number of cases, these popular historians will look at evidence that supports their narratives. David McCullough frequently relies upon a narrow base of primary sources and a selective use of secondary sources to buttress the veracity of his often triumphalist narratives. This has led to some mistakes on McCullough's part. For example, John Adams misquoted Jefferson, claiming Jefferson called Adams "the colossus of independence.” The problem was Jefferson did not utter this and McCullough pulled the quote from a book on Daniel Webster. While a misquote like this might seem like a tempest in a teapot -and to a degree, it is - it reflects how McCullough's biases can promote a casual disregard for historical methodology.

One area though where journalists possess some advantages over specialists is in contemporary history. Their occupation has given some of them access to various individuals and a good journalist knows how to pull a clear narrative out of a very convoluted present. Cornelius Ryan's trilogy on WWII went through a very novel approach of trying to solicit as many interviews as possible to render a complete picture of D-Day, Market-Garden, and the Battle of Berlin. In some ways, Ryan was doing bottom-up history in 1959 before it was fashionable. Rajiv Chandrasekaran's Imperial Life in The Emerald City: Inside Iraq's Green Zone has a pastiche of details about the American occupation of Iraq that probably won't find their way into the archival record (my favorite nugget is when the three guys tasked with privatizing Iraq's economy met with a German team who did the same with the GDR's economy laughed at them and told them "Don't bother starting."). Biases and writing the history of an incomplete story are both real issues with journalists' contemporary histories, but they often are the ones on the ground floor of major events.

Some journalists write good history books. Some write terrible, misleading, misguided ones. There isn't any hard and fast way to tell which are going to be which.

The notion that academics exclusively write good history is certainly a false one, as is the idea that good history must be difficult to read. There are plenty of crossover and general audience books by academics. There are also some great examples of historical works by non-academics that meet or exceed the "normal" standard of work for academics (as someone who has read a lot of academic monographs, I can attest that aside from being poorly written, some of them are just bad -- so I think it is a bit unfair to hold journalists or anyone else up to a rather often unrealized standard even among academics).

If there is a "common problem" with journalists in particular, it is in these two tendencies that are common to their discipline:

• Journalists tend to work fast. They tend to like to jump into a topic for a week or so and then quickly move on to the next. This is not a good trait for history, where research can take years and one can spend decades thinking through a topic to really understand it. When I have found journalistic works of history I was impressed by, it is invariably the case that they bucked their usual trend and spent approximately a dissertation's worth of time (e.g. 5-10 years) researching the topic.

• Journalists can tend to want to come up with a snappy, one-sized fits all sort of argument. They want to boil down history into one or two simple themes or lessons, usually ones derived from their present-day concerns. While I am not averse to looking for lessons in history, or even having present-day motivations for an exploration of the past, if you go about this superficially you will get superficial results. (This is a gripe I have heard leveled towards Isaacson's works.)

If you are curious what people who have spent decades thinking about a topic think about these works, search out reviews by historians. Of course, academic historians are hardly infallible and are prone to jealousy and clannish behavior when it comes to outsiders poaching on their "turf." Sometimes their criticisms are legitimate, sometimes they are nit-picky. So, again, I don't think they are necessarily the gold standard here -- there isn't one, in general.

The best works of history by journalists combine deep knowledge with clear, thoughtful writing. No different from academics, in that sense.

It truly just depends on the writer but I am always wary of history written by non-historians. When I went to the Gettysburg College Civil War summer program a few years ago I met a lawyer (whose name escapes me) who has written some of the most definitive books on Grant's 1864 campaigns because while he chose the law as a profession he had a true passion for history. But I think he would be the exception not the norm.

In my view, there are two major difference between the two: Use of sources and writing style.

First, the way the writers use their sources will vary based on whether they are a journalist or a historian. A historian's use of sources will be extensive, with lots of footnotes and corrections. Historians will also use as many primary sources they can to write their work. Journalists might use the historian's work to write their own, and might not have as many sources as a historian.

For writing style, the historian will write only to prove their thesis, so the writing can be dry and some people would find it boring. Historians want to pad their work with evidence and detail to really flesh out the historical details on their subject. If you want to be entertained, then go with a journalists writing. They will try to tell a story more than give you the historical details of events. Journalists and historians are taught to write in completely different ways.

Hope this helps.

Reader's opinion. Personally, I'm wary of scholars' books with blurbs from other scholars that use the words "definitive" or "authoritative," but not "readable" or some other adjective that promises a good narrative. Definitive and authoritative often mean dry collations of fact with less regard for personalities or the more riveting events.

Journalists are inherently popularizers; their job is to take complex issues, explain them to the greatest number of people in the most succinct way, and to keep them reading to the end. That said, journalists often zero in on events and people that more traditional historians may relegate to the sidelines, if they're not relevant to the scholar's theory or point. Really good writers (Max Hastings leaps to mind) blend rigorous detail with ripping yarns and fascinating characters.

I'll leave it to the historians to weigh in on Isaacson's reliability, but I just wanted to note that journalists seem to include details that some historians don't see as "important."

On the same line as the topic: Which examples come to mind when thinking of journalists writing good history? A good portion of the works listed on the Books and Resources list were written by journalists. Any other particularly strong examples?