I just finished reading Old Man’s War by John Scalzi and I thought it appropriate to discuss the difference between inspiration and imitation. It is interesting to see the amount of reviewers panning the novel because of its likeness to Starship Troopers by Robert Heinlein. Certainly this comparison is nothing Scalzi has tried to hide. He pays homage to Heinlein in the book’s acknowledgements. He even went so far as to say,
As the retreading of Starship Troopers in Old Man’s War makes abundantly clear, I’m not horribly concerned about when I’m treading on old story tropes and indeed enjoy playing with them. What I worry about is using them to tell a story that readers will enjoy. I also try not to repeat myself (or when I do, for example in Zoe’s Tale, to tell the tale in such a sufficiently different fashion that it’s mostly new). 
To call Old Man’s War a retreading of Starship Troopers is a bit of an exaggeration in my mind. Sure, it is easy to draw comparisons — in both stories, a soldier rises through the military ranks to fight a war against an alien (arachnid) species. But all of this is just the backdrop, which serves as a typical plot line for many military science fiction novels. What makes Old Man’s War an inspiration rather than an imitation is that Scalzi has a unique viewpoint to offer. He is not just rehashing old ideas, but is offering a new twist to what is really just a classic trope. The novel starts off with what I find to be a brilliant first line, “I did two things on my seventy-fifth birthday. I visited my wife’s grave. Then I joined the army.” Right away, we have a protagonist (John Perry) who is very different from Rico, the young protagonist of Starship Troopers. Perry has life experiences and is joining the army as a way to get a new body and in essence, start a new life. Rico, on the other hand, defies his father’s will and joins the army as a path to full citizenship. Scalzi explores new ideas, such as the transferring of one’s conscious to a superhumanoid, touching on subjects such as race and sex, where much of Heinlein’s focus is on libertarian social and political themes. Scalzi also offers technological ideas that include a skip drive for traveling through space and a BrainPal, which serves as an AI neural communicator.
Scalzi is not the first author to pay tribute to the giants before him. Gene Wolfe attributes his inspiration for the Book of the New Sun tetralogy to Jack Vance’s The Dying Earth series. In an interview, Wolfe mentions that he decided “to rewrite The Dying Earth from [his] own standpoint.” He elaborates further:
When you read wonderful books sometimes you think, “Gee, I would like to do that”; and you go off and do it, trying to make it different enough that you are not really ripping off the author, but rather writing something in the same vein using some of the same ideas. I have never concealed a debt to Jack Vance and a debt to Clark Ashton Smith as far as that goes. I think Vance is very much in the debt to Clark Ashton Smith. 
It is not uncommon to borrow themes or even technology from previous works. Orson Scott Card borrowed the faster-than-light communcation device, an ansible, from Ursula K LeGuin’s novel, The Dispossessed. Vampires, werewolves, and other mythological creatures also find their homes in many novels throughout genre fiction.
So where is the line between inspiration and imitation? Obviously there are no hard and fast rule. It ultimately comes down to the reader. Does he or she feel that the novel is offering something new and compelling? Are there new ideas to explore with previous tropes that will come off as more than a Hollywood remake? Is the story different enough? There are many novels that end up as cheap imitations, some of which even make it to publication. But generally speaking, the publishers and readers are not easily fooled.Footnotes: 1. Whatever. John Scalzi. 2009. <http://whatever.scalzi.com/2009/04/04/reader-request-week-2009-10-writing-short-bits/>
2. Lupine Nuncio. James B. Jordan. 1992. <http://mysite.verizon.net/~vze2tmhh/wolfejbj.html#style>