The TV series contradicts the TV series (UNIT dating, three versions of the sinking of Atlantis, among others), and the TV series is considered the Holy of Holies as far as Doctor Who canon is concerned.
Then you had monthly book releases between about 1990 and 2004, three books every six months between 2005 and now, an audio drama released once a month since 1999, plus several spin-off audio dramas, the comic series in Doctor Who magazine/Doctor Who Monthly/Doctor Who Weekly (and now Doctor Who Adventures as well), some animated webcasts...
...And the current series is referencing some events in some of these as canon, and forms the basis of some of the events in it's backstory from some of them (though nothing that makes any of them required reading, because the BBC aren't allowed to do that).
And then there's the little matter of Shada. Is a half-made, never aired story canon? And if so, and if you take the animated webcasts as canon, which version of Shada is canonical? (though, I buy into the 'both' arguement)
This might sound stupid but, why do they have to be consistent with each other? The TV series, comic and radio series can each be in a universe of their own, seperate. Writers can explore different angles. If there's so much contradiction, and even if there isn't, what harm is there from using that formula?
I've rarely watched Doctor Who, bear that in mind please, if you post a reply.
Well, firstly each book/audio drama/etc (or rather, most of them) are set in between two episodes of the tv series.
Secondly, there are ones that branch out from established continuity. Typically in order to use non-canonical Doctors. (The Unbound series).
Thirdly, there is continuity between the episodes of the series, the books, the audios, etc. It just contradicts itself at times. The books, to my knowledge, typically only contradict the audios (and the other books) as much as the tv series contradicted itself (though... That doesn't say much. It's established in the Pertwee UNIT stories that they're set in the late 70s-early 80s... But it's also established in a Davison story that the Brigadeer retired in 1976)
Fourthly, there are audios set within the New Adventures book series (With Bernice Summerfield) and within the Comic strip series (with Frobisher). The former being a archaeologist from the future who drinks alot, and has a sarcastic attitude to everything, the latter being a shapeshifting penguin (well. No. A shapeshifter who's favourite form is that of a penguin.)
Fifthly - What's the fun of saying "well, they're in different continuities". Half the fun of fandom is piecing together the continuity nightmare.
With Hitchhikers, on the other hand, they're not even intended to be the same universe, with each one being, basically, a different version of similar events. Which reminds me. There are, in certain places of the Doctor Who series, hints that Hitchhikers is canon. Additionally, the Doctor has met Douglas Adams. Which means, well, 'whuh?'
