I have always thought that Catherine Morland has received a bad rap, not only from the characters in the novel, but readers over the years have misinterpreted her, in my opinion. Catherine was able to understand the monstrously realistic nature of General Tilney (in other words not a monster, but just as bad as one) through her own imaginative deductions. This relates to Derrida when he writes: "By orienting and organizing the coherence of the system, the center of a structure permits the play of its elements inside the total form."
Catherine may have been creating stories inside her own head of what was fantastical and simply untrue (as Henry Tilney points out), but I do think her technique was to reframe what was indeed happening through this sense of seeing the signs and putting them into play, almost lessening its extreme impact in anticipation of informing Henry. His reception of the information was initially to say that Catherine was being unrealistic with her accusations, thus not taking them seriously and to heart. As the narrative progresses, however, both he and the reader come to find out that yes, she was right, but not exactly, and not in they way they all presumed.
Austen's focus on negation to me signals her disproof of things empirically (We can only disprove something. We can never indesputably prove something). As Derrida writes, "Nevertheless, the center also closes off the play which it opens up and makes possible." So, Catherine's centering actually opens up the possibilites rather than creates a situation where she is seen as being irrational. When she opens the cabinet in the light of the morning and realizes how absurd her thoughts had been (seeing a basic laundry list inside, instead of the bones of the dead wife as she expected or whatever else she could have imagined), this moment opens up the possibility that there could be more to the story of the Abbey. Catherine is creating and pinpointing the center, and Austen is, through her narrative techniques, disproving the possibilities, thus honing the options down considerably: down to one possibility, in fact.
Catherine ultimately excels at creating these structures, and I would argue that the other characters don't exactly understand or comprehend how to make them, especially Henry, who is such a know it all. What is also interesting? This all takes place in an old abbey which represents the old guard, the past, the old structure that had existed before the abbey was converted and its meaning was lost through history. This reminded me, of course, of Burke's Reflections on theRevolution in France, and his defense of tradition, the monarchy, and the clergy in the face of violent reform.
In Austen's work, Catherine mediates between the forgotten , Gothic past and the progressive future. When she enters the Abbey, she brings her own interpretation of the signs that she is presented with, and so she serves as the character who will solve the ultimate crime of improvement amidst the Gothic ruins. General Tilney's intention to "improve" the future of his family line results in an innocent single female to be placed in a truly dangerous situation without consent of her parents or chaperone. General Tilney should have been protecting her as the fortification of the Abbey had protected the inhabitants in the past, yet he didn't. He placed improvement above traditional chivalry and protection.