Denethor's madness.

[King of the North]

Right from the get go when u first meet Denethor (TTT EE) he is a bit crazy as he insists that Boromir goes to Rivendell and claims the One Ring for Gondor. By showing from the beginning that Denethor is mad, PJ did not create good character. And if you watch only the theatrical versions of the movies, Denethor is even less interesting.

Originally posted by Tuor of Gondolin
There was no character arch, which even movie Faramir had, to some extent.

Very true. Movie Denethor did not go through any journey and essentialy remained static throughout his entire role in the movies. The death of Boromir only contributed Denethor's insanity, but it did not start it because as I stated above, the Steward is somewhat insane from the very beginning. In the movie we never see the good leadership qualities that Denethor had in the book until he lost his mind to the Palantir.

[The Saucepan Man]

I am not really a fan of film Denethor (although I do think that John Noble plays the character as written superbly). But, realisitically speaking, there was not enough time within the last film to establish Denethor as the proud but noble character we meet initially in the book and then have him change into the suicidal and infanticidal character that he is at his death. The contrast would not have come across credibly within the time available to devote to him on screen. And so it made sense to have him as an unsympathetic character from the outset.

But I think that there is a change in his character, albeit subtle, throughout the film. As Boromir88 points out, he only becomes really psycho once he sees the size of the force approaching Minas Tirith and then is given to believe that his remaining son is dead.

As for the original question, I think that there is sufficient in the film to establish the credibility of his despair, even without the Palantir. He is fully aware that Minas Tirith cannot hope to hold out on its own against Sauron without having to be told as much by Sauron himself. Add to that the death of his favoured son and his conduct with regard to the defence of Minas Tirith and his attitude towards Gandalf (supplemented by his credible reluctance to give up his throne to a "usurper") seems believable to me. The reality of Sauron's assault on the White City and the death of his remaining son (or so he believes) is credibly sufficient to push him over the edge (if you'll excuse the pun ).

[Anguirel]

I'm being a Devil's Advocate here, but isn't it amusing that we criticised Faramir's "character development journey" but are now declaring that Denethor is too static?

At least everyone agrees they got Boromir right. Aside from the question of the hair.

[King of the North]

Originally posted by Anguirel
I'm being a Devil's Advocate here, but isn't it amusing that we criticised Faramir's "character development journey" but are now declaring that Denethor is too static?

I never criticized Faramir's character development.

[Eomer of the Rohirrim]

I will. It was illogical.

Anyway, that's for the Faramir thread. As for Denethor, he was basically just a jerk all the way throughout. A real shame I thought.

In the film, Denethor seemed to be in denial about Gondor's ridiculously low chances in the War. Then he sees Mordor's army, his eyes open up (literally) and he goes insane. I think that is as central an explanation as any, within the film's logic.