Why did Harry and the others think they could rescue Sirius?

Question

Harry sees a vision of Voldemort tormenting Sirius in the Dept. of Mysteries. This leads him to rush off to try and save him, and when his friends are unable to dissuade him from going, they insist on going too.

If Harry's vision was correct, he would have ended up confronting Voldemort in the Mysteries chamber. Did he really think he had a chance of A) not dying and B) saving Sirius and escaping? Understandably, Harry was in extreme emotional distress seeing Sirius, his only living family and father figure, being tortured and likely killed. His reaction pure dumb bravery, like jumping in front of train to save someone you love who is on the tracks. Why wouldn't one of his close friends, especially someone as smart as Hermione, point out that even as a group they almost certainly would all be killed by Voldemort, doing Sirius no good and causing the very last thing Sirius would want?

I've always thought of this as a plot weakness, and that Voldemort could have used a much more clever pretense to lure Harry there.

Answer 1

Hubris

As Harry mentions several times in the books starting in Harry Potter and the Philosopher's Stone Harry's beaten/survived Voldemort once/multiple times, so he's going to do it again! By book five Harry has beaten/survived Voldemort three or four times depending on how you keep score. First as a baby, in what amounts to a deus vult situation. Then in First year when he murders Quirrell-with-voldemort-in-his-head, then second year with Riddle's Diary and a godawful-big magic snake (where he successfully performs a rescue mission), then fourth year with Voldy & his Death Eater pals.

So now we come to Order of the Phoenix where Harry's visions, accurate to this point, show just Voldemort and his captive. Well, Harry's escaped fully-formed Voldy with a bunch of death eaters. Plus he's rescued someone and defeated Voldy-as-contained-in-Riddle's-Diary with a single friend who was more-or-less unarmed (Ron with his broken wand). So the assumption that Harry, with Ron, Hermione, and a few extras just in case can take the most dangerous wizard of all time on their own isn't quite as crazy as it sounds. At least to teenagers. After all, teenagers are known throughout time and across cultures for having a high opinion of themselves, thinking they can do better than their elders, and not really grasping their own mortality. Combine that with the fact that, "Well hell it worked before!" and you have a perfect storm for Bad Ideas!

Answer 2

You could call it a plot weakness, a necessary plot device (or there'd be no plot), or just sheer dumb bravery by all the characters involved.

Note it's not the first time they did something as reckless as this. In the very first book, Harry/Ron/Hermione went after "Snape" to stop him from stealing the Philosopher's Stone, even though they obviously had no chance of beating Snape in a fight. Hermione was in that group too, and she must have known they could not win, yet she went along anyway. Similarly, in book 3, after Sirius (in dog form) took Ron, Harry/Hermione followed, even though they knew it's clearly dangerous.

One more thing: book 5 is the time when they are taking the OWLs. If they pass, then they become fully trained wizards & witches. If anyone is going to defeat Voldemort, it would probably be OWL holders like them. That level of experience may have been a factor in their decision to go.

(Which doesn't change how it was sheer dumb bravery for them to go after "Snape" as first year students.)

Answer 3

Dumbledore's army

Harry and company had just spent the better part of a year practicing magical combat, to great success. Many of them learned to successfully cast spells like the Patronus that are repeatedly classified as so advanced that many adults do not know how to properly use them. They have felt great personal growth in their wizarding abilities, and have been preparing explicitly to fight against Voldemort and the Death Eaters. I'm sure that part of their willingness to fight is akin to wanting to play a real game after months of scrimmages.

No one to lean on

Despite years of evidence in their own abilities to handle dangerous situations, the adults in their life that they respect tend to either dismiss concerns or shelter them from danger. On top of that, Umbridge had them locked down pretty thoroughly, making communication with those adults pretty difficult, if not dangerous.

Ultimately, these are kids who have a lot of built up frustration from a year under Umbridge's boot along with a nonstop barrage of disinformation from the ministry of magic. They are afraid of the way the world is changing, but the adults in charge are either denying the danger or actively facilitating it. Reckless or not, they acted out of desperation as much out of arrogance.

Answer 4

To add more detail to the other excellent answers:

Earlier in the book, Nagini attacked Arthur Weasley. Harry had a vision of this, and felt responsible because he didn't do anything with that vision. I don't believe the book mentions that guilt, but it's implied. He was living with that guilt. He didn't want to feel that guilt again, with arguably the closest thing to a parent that he's had. He had to take action. You could say that Voldemort planned this sequence of events as Dumbledore/Snape predicted. It's why they pushed Harry into Occlumency. In a strange way, Harry, perhaps through the wand, was allured by the connection to Voldemort. Which sadly, ultimately, led to Sirius passing into the veil.