
To be clear, insanity is a legal term pertaining to a defendant's ability to determine right from wrong when a crime is committed. Here's the first sentence of law.com's lengthy definition:
Insanity. n. mental illness of such a severe nature that a person cannot distinguish fantasy from reality, cannot conduct her/his affairs due to psychosis, or is subject to uncontrollable impulsive behavior.
Insanity is a concept discussed in court to help distinguish guilt from innocence. It's informed by mental health professionals, but the term today is primarily legal, not psychological. There's no "insane" diagnosis listed in the DSM. There's no "nervous breakdown" either, but that's another blog.
Where did this saying come from? It's attributed to Albert Einstein (probably not), Benjamin Franklin (probably not), Mark Twain (probably not) and mystery writer Rita Mae Brown (probably so) who used it in her novel Sudden Death. It's not clear who said it first, but according to at least one blogger it's "the dumbest thing a smart person ever said." The catchy saying has gathered steam in the past few years (example I, II, III), and regardless of the source, it's gotten a lot of mileage.
I'm not in the habit of slamming cute sayings (with one exception), but I think there's a dark underbelly to this one. I've started hearing people use it in the service of avoidance, which is a defense mechanism. Rather than facing their fears, they grab on to this saying for protection against possible failure, pain or rejection. Some examples:
The definition of insanity doesn't have anything to do with jogging. It's important to keep grieving, jogging and asking people for dates because these are areas of life that require some repetition and are quite sane. As a therapist, when I hear these statements I can collude with the protective bubble of the socially accepted catch phrase or challenge it. When met with the examples above, I'll challenge.
I think the confusion behind this statement is best illustrated by these two words:
Perseveration: the pathological, persistent repetition of a word, gesture, or act.
Perseverance: steady persistence in a course of action in spite of difficulties, obstacles, or discouragement.
Some forms of dementia, traumatic brain injury, anxiety and OCD can cause people to perseverate. They repeat words and tasks or try repeatedly to solve problems, but are left frustrated and unsatisfied. They're not necessarily insane, but stuck in a non-productive pattern due to a glitch in brain function. Some medications or CBT tools may prove helpful.


So how do you tell the difference? Perseveration feels compulsive, hopeless, helpless, automatic and unsatisfying. There is a desire to stop, but stopping doesn't feel like an option. Perseverance feels like striving toward a noble goal, and whether or not it's reached it there is virtue in the effort.
Perseverance is a strong, valuable quality. Perseveration is a troubling issue needing clinical attention. Don't let a quaint saying blur this distinction.
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You're welcome to perseverate at my website or facebook page.
Links:
[1] http://www.psychologytoday.com/experts/ryan-howes-phd-abpp
[2] http://www.psychologytoday.com/blog/in-therapy