If anyone really knows everything about everything in the DC Universe, it has to be Batman. He's not the smartest character in DC Comics, but he's not far from number one. His nickname of the World's Greatest Detective stems from the immense level of knowledge he possesses as a crime-fighting genius – and it's all intentional.
Gotham Adventures #56 by Scott Peterson, Tim Levins, Terry Beatty, Lee Loughridge, Albert T. De Guzman, and Harvey Richards gets to the basic explanation of why and how Batman knows everything. The answer is simple: the why is because he thinks he needs it, while the as is to do intense research to prepare for a scenario that he needs to know.
When taking a closer look at his reasoning and how it affected his adventures (and those of the Bat-Family), it becomes clear why Batman is a great detective.
Batman seeks knowledge for a simple reason: in case he needs to know
As Gotham Adventures #56 reveals this truth
Gotham Adventures #56 – set in the world of Batman: The Animated Series – focuses on the Riddler, or more specifically, a Riddler impersonator, which becomes evident when Edward Nigma appears utterly confused after the Dark Knight interrogates him about a riddle that doesn't belong to him. Upon further investigation, the Caped Crusader and his Boy Wonder, Robin (specifically Tim Drake, Batman's most trusted Robin), discover that Arkham Asylum has a missing inmate: Kim.
Before Batman can track down Kim, Batman discovers that the Riddler – enraged that anyone would dare copy him – has escaped from Arkham Asylum to confront his wannabe. While Batman and Robin try to solve Kim's riddles, the Riddler confronts Kim directly at her hideout (her address, which the Riddler found online). A fight breaks out and Kim admits that her five riddles were inspired by the five senses shown in the film In the Realm of the Sensesdirected by Nagisa ÅŒshima.
While the Riddler criticizes that no one, not even Batman, would have the resources to understand a riddle from such an obscure reference, Batman appears to arrest the two men. To the Riddler's surprise, he underestimated Batman. Kim asks Batman if he knows who Nagisa ÅŒshima is, to which Batman gives a detailed description of her biography, although he admits that he has never seen one of her films (he would rectify this by the end of the issue). When asked why he knows so much about him, Batman says: “In case I need it.”
How does Batman know and remember everything?
Memory retention is a superpower
At least since the Silver Age, it has been established that Batman has eidetic memory (better known as photographic memory). His memory retention is practically Bruce Wayne's superpower, allowing him to slowly replay moments in his head, little by little, down to the last detail, whether he saw it happen days ago or even years ago. Furthermore, years of memory can be stored in Batman's head like a memory palace (much like Sherlock Holmes), allowing him to save and access it whenever necessary and at any time.
Batman can get that information out of his head at any moment.
So if he needs to remember something he learned a long time ago, even something as obscure as where Nagisa ÅŒshima was born as a post-WWII Japanese director, Batman can get that information out of his head at any time. Even more impressive is how the same ability became common for other members of the Bat-Family. For example, Barbara Gordon shows how your photographic memory works like a computer in Batgirl #35 by Cameron Stewart, Brenden Fletcher, Babs Tarr, Maris Wicks and Jared K. Fletcher.
Why exactly does Batman try to know everything?
A good detective is always prepared
Batman tells Kim in Gotham Adventures that he learned such useless information in case he had to, but the question remains as to why he would prepare for something so hypothetical. Some may wonder why he spends so much time researching information he may never need. It turns out that he was prepared to find out about ÅŒshima by chance, but it was a small chance. It's hard to understand why anyone would spend hours learning anything on a whim, for the small chance that it might be useful. Simply put, This is what separates Batman from other super geniuses and detectives: he is always prepared.
In some cases, like when he wrote plans on how to kill the Justice League just in case, Batman might be a little too prepared. However, even if overly prepared, a good detective needs to be prepared. Doing such extensive research for each and every hypothetical scenario and keeping a mental photographic account of all this information justifies Batman's position as the World's Greatest Detective. There may be others out there who are more qualified or smarter than you. Batmanbut none willing to be as mentally prepared as he was.
Gotham Adventures #56 is now available from DC Comics.