[Kath]

I agree with rutslegolas about Denethor's sending of Faramir and company to Osgiliath being pointless but at this point Denethor's mind was already in the final stages of being overthrown by despair. He had already lost the son he loved best and I think he was desperate to see something of Boromir in Faramir. He may have honestly believed that if Boromir were there he could have taken Osgiliath back and sort of guilt-tripped Faramir into going by promising love if he lived up to the legend of Boromir.

Denethor was pretty much insane by this point anyway so he may have just not had a clue what he was doing! But then, I'm not sure if I'm remembering this correctly it may be a film thing that has forced it's way into my mind, but didn't Denethor say something about fighting being pointless and they were all going to die anyway so decide how you want to? Because if the answer to all that rambling is yes then maybe he thought Faramir would prefer to die in battle - with honour.