Because of the neurological research coming out over the last decade or two, psychiatry is increasingly making a distinction between denial and unawareness. Some of the research is being done up at Dartmouth MS by folks I admire and used to work with, so I keep up with this more than other areas.
Everything has been in the "denial" category since Freud, or before: the idea that mentally ill people really do know, at some level, what reality is, but hide it from themselves. Therapy was a way of developing insight, and having the courage to accept the unpleasant.
Unawareness, in contrast, is the idea that certain brain dysfunctions make the owners of those brains unable to see their illness, no more than a blind person can see, or even more exactly, than a color-blind person can distinguish colors. Like an amputee who feels a phantom limb, or like Oliver Sacks, losing the sense of ownership of a limb after injury, they cannot perceive their illness, regardless of the evidence submitted. Dr. Flashman gave the example of the patients who believed he had implanted chips in their brain, shown their chipless MRI's. The responses were varied - my sort of chip doesn't show up...that's not my MRI...you doctored the photo... but none were able to muster even a 0.1% acceptance of the no-chip idea. Not evn in theory. Not even as a "what if" scenario.
We are moving more and more lack of insight from the "denial" pile into the "unawareness" pile, for psychotic disorders certainly, but even for mood disorders when they are untreated. How far will this go? Will it turn out that no depressed people ever respond to any offered advice or insight, but only to the intervention of attention, of exercise, of medication, of practicing agency? Lincoln's comment that people are about as happy as they make up their minds to be might turn out to be completely untrue, and useful only for the reminding the folks outside the depression that nothing, absolutely nothing they advise is going to have the slightest effect.
I am increasingly convinced of this for many illnesses, and it makes me feel shame at the conversations I have had over the years with patients, attributing (usually, but not always, unconsciously) their lack of insight to some stubbornness or cowardice on their part - a refusal to engage reality rather than a biological inability to perceive it. It's not just a waste of time. It's thirty-plus years of unnecessary cruelty.
If you absorb this, you will see that it makes things both better and worse. If the patient is not going to be convinced, whether you explain for two seconds or two hours, why bother to give any explanation at all? Or if you listening to her for two hours will make no more difference than listening for two seconds, why listen at all? Isn't it just a waste of time and ultimately cruel, pretending to a patient that her opinion makes the slightest difference when if fact it doesn't? So let's just ignore everything she says until we get a guardian then, and hold her down and give her medicine and be done with it. Why any charade?
I don't think it takes much imagination to see that as a chilling scenario, and an enormously bad precedent to set.
But is badgering a deaf person because they can't hear any better? Because even if the mental health practitioner is speaking in the kindest tones, is really rooting for the patient to "get it," and has the best intentions, if we really think that underneath it all they are denying reality, that some trick or intervention on our part will help them turn the corner and begin to see, then badgering is what we are actually doing.
It gets worse. It may apply to a high percentage of all beliefs, not only to mental illness.
Update: Roper's comment reminds me that I have at least a half-dozen professionals reading here, so I should provide some links. Xavier Amador looks like he'd be pop psych, but he is not. His books cover a fair bit of the brain research.