Sareth is right.

The Doctor had to intervene in the Last Time War and basically when the Time Lords had decided that it was better to erase the history of the universe in order to save Gallifrey, the Doctor instead removed Gallifrey from the universe to save the innocent worlds not involved in the war from complete annihilation.  It's also implied a few times that the Doctor was quite the general in the Last Time War and was responsible for many defeats of their enemies.

When seeing the extremes his own kind would go to to save themselves, he realized they were not much different than their enemies--in fact, they had come to see themselves as gods amongst "mere mortals"-- and his view shifted from assuming he was a Time "Lord" to becoming an observer and simply enjoying watching other species live and evolve--particularly humans.  He also began to act as a protector of the innocent and its implied it is because of his guilt and shame for his and the other Time Lord's former arrogance and hubris and guilt for being the one to "pull the trigger" on his own people.

If you note, the Doctor often does not end up where he plans to go and while it's been implied for some time--particularly in the new series--the TARDIS itself has something to do with where he ends up.  The episode recently titled, "The Doctor's Wife" really shows this. The Doctor and TARDIS have a symbiotic relationship and the TARDIS is composed of pure time energy that was present only at the Big Bang and is itself intelligent--with a desire to bond and serve with a Time Lord.

So the TARDIS is like the Doctor's subconscious in a lot of ways and it responds to his desires and motivations even when he isn't consciously aware its doing so.  Because he feels guilt and a need to atone and looks to helping others (particularly humans whom he is constantly shown admiring as unique in the universe), the TARDIS "nudges" his "fun expeditions" to points in time and space where there is a threat to or need by the life forms he is attached to.

So he is drawn by love and desire for humanity's existence but cursed with always showing up at the most critical and threatening points of its existence because of his sense of guilt and the desire to atone.  A hero who must always fight and never is able to lay down his sword--though he longs to.

I love the science fiction strengths Russel brought to the series.

Lol--I was up late...there ya go.

I guess since the Blessing was solved, there was no need for the doctor to get his hands dirty?

Yeah--Torchwood does sort of impinge on continuity sometimes...Cie le TV.

I'll agree the Doctor could check exactly where he is going and that he chooses not to--but I don't think that invalidates my point.  He doesn't want the responsibility after having had it back in the day...it was too much.  It's a psychological coping mechanism that does put his companions at risk...but on the other hand it also puts him at the right place at the right time.

Essentially, he's always is up to the adventure and he is willing to do the dirty jobs that must be done if he has too--he just isn't up to having to face a list of problems and responsibilities so he simply trusts the TARDIS to pick the assignments for him.  Sometimes he gets to have fun and othertimes he has to sacrifice but he's spared the pressure of having to face it daily.

Think about it...all the problems in the world--all life or death--in your inbox every day.  I'd avoid and want a way to cope too without having to always think about it.  I thin k anyone would go insane--even a Time Lord--if they had to carry this.  You could even argue that's exactly what happened to the Time Lords and that's why the Doctor is afraid of the obligation.

Essentially, the Doctor is quite similar to someone dealing with PTSD Can you blame him?

Sinperium answered it before I could :

I would pose a fair question, if you had killed 1 billion + individuals, that their blood was on your hands, and it had really solved nothing (aka daleks are still alive, threatening the universe), would you finally take to heart the lesson that violence is not the answer?

Would you become a paragon of peace, to use reason and discussion to stop the proliferation of violence?

The doctor is in many ways a paragon of peace, and I believe this is his most endearing quality to the viewer.

He is not perfect in this, but the point is that he tries not to use violence.

That is all I was talking about, nothing more or nothing less.

If you want to get some real life experience on this phenomenon, enlist in the army and go overseas and start killing people with the rest of those guys, and/or talk to a few soldiers that have killed a few people in combat and ask them if violence is the right way to go about things. 

Personally, I have never killed another person in combat despite having served in the armed forces in a warzone.  I have had many friends that have however and they are strong supporters of a peaceful solution to solving problems (as am I).  It is the governments/private interests that make money off the conflicts that are the greatest barrier to peaceful conflict resolution. 

I enjoyed the episode where the human bankers had sold out humanity to an alien monster on a media satellite orbiting the earth.  The situational comedy of that episode was downright awesome.  Writers of Dr. Who and I see eye to eye on a great many things, that is one reason I enjoy the show as much as I do.

Yeah that would be a god awful mess!

Lol good reply!

My timelord source says no.

In case you were wondering what he saw, it was just him in there, probably waving enthusiastically. 

I think he saw himself, in the Tardis (hence the sound), alone. He fears his own decisions and the guilt and tragedy they incur. This would tie into the storyline with Rory, whom the Doctor puts a lot of heavy decisions on that he doesn't trust himself to make. Also, the episode, where the minotaur basically tells the doctor they are they same - tumbling through space in a box, forever alone, and that death would be an accepted release for such a creature (remember the overarching storyline of this season? yep). And finally, how the episode ends - as many before it - with the doctor alone in the Tardis looking for the next companion.

Well, this season was filled with more red herrings than something that's filled with a lot of red herrings. Totally did not see that coming, I was expecting  that the Doctor that died was made of Flesh, but not a robot, since well, robots don't die. But there is a logic to it, he didn't need to die, he just had to be there and go trough the events that were fixed in time. The robot being hit and burned, that's all. This ending actually made a lot more sense than the previous season. But still, why did the TARDIS explode last season? Guess we won't find that out until 2012, when it would seem that this Doctor will regenerate. Also, in the 50 years the series has been on, has no one used a plot that involved the title? It's been a running gag, but never a plot? Weird. Waiting a year for the next season is going to be a pain, especially since it will be shorter. Oh well, now I have to write something odd, so when people see the text with the spoiler tag on, they'll go "What!?:. a dinosaur, but whoever thought that the plants would eat everyone.

The bit with the Dalek was great "Imagine you were dying, imagine you were afraid and a long way from home, in terrible pain, just when you thought it couldn't get any worse, you looked up and you saw the face of the devil himself". That was probably one of the best lines I've ever heard a Doctor say. The nod to Nicholas Courtney, who played the Brigadier, was very touching. In the first episode of this season, the doctor did say he was 200 years older. I thought, that since for him time still passed when it went all wibbley wobbley, he spent most of that time locked up by Churchill, but he was supposed to meet River a bunch of times, like on Easter Island. Also, we didn't get to see him do any of the stuff in the intro to the Impossible Astronaut. That's something that seems to be a common theme in this series, it skips over a lot of things. That's what made the relationship between Amy and the Doctor seem a bit forced at first. If they had actually gone on an adventure, rather than him just barging in and making her cook, it would have made a bit more sense for the Doctor to imprint on her memories a lot more. Hmm, now that I think of it/watching the intro of the Impossible Astronaut on youtube, the question "who" was used a lot in that episode.   giant octopus in his pants.

Well, Doctor Who has been going so long, with so many people involved, that there's bound to be a few paradoxes.   And personality clashes.

Best regards,
Steven.

Oh damn unacomm, you're killing me. Well played.