The uncertain definition of "competence"

The excellent entries continue on "The New Old Age." Here is the discussion on mental competence, the legal way of determining whether someone has the cognitive ability to make decisions for oneself, usually meaning signing documents. Often, that determination varies even by the type of decision to be made: for example, voting, making a will, or entering into marriage may all have different thresholds for "competence."

The entry in "The New Old Age" considers competence in the context of non-deceased wealthy philanthropist Brooke Astor's later years when she had Alzheimer's disease. Here's a bit of the entry:

. . . Alzheimer’s sufferers may experience days of comparative lucidity alternating with days of bewilderment. Cognitive ability “may even vary throughout the day,” said Dr. Ronald C. Petersen, a neurologist at the Mayo Clinic who chairs the medical and scientific advisory board of the Alzheimer’s Association. “A person might be
relatively sharp in the morning and by evening be quite confused.”

Caregivers are familiar with the late-day agitation called “sundowning.” Medications, disrupted sleep, social stimulation and even a minor cold can affect these diurnal cycles. Though a variety of doctors are expected to testify during the two-month trial, they may shed little light on whether Mrs. Astor had, in legalspeak, “testamentary capacity” on a particular January afternoon in 2004, when she altered her will.

. . .

The bar for establishing testamentary capacity is set fairly low. The person in question needs to have a general understanding of her assets, know to whom bequests are normally left, and be able to state what she wants to do and explain why.