President Biden’s poor performance at the debate is only the latest in a series of gaffes and blunders, both physical and mental, that have many scratching their heads when thinking about his brain.

There have been calls both within and without the Democratic Party for Biden to step aside; some fear that even if he wins the election, he might be in no condition to finish what he set out to do. Some declare him “too old,” and others are preoccupied with the likelihood of his having specific diseases that might explain his performance. Many have asked the president to reassure the public by taking a cognitive test, something he refuses to do.

While spin doctors are unethically diagnosing at a distance on cable news outlets, respectable experts must remain silent, forbidden by the Goldwater Rule, a provision of the American Psychiatric Association’s Principles of Medical Ethics, which restricts clinicians who have not personally evaluated a candidate from rendering public medical opinions.

Health literacy might be useful, then, for civic education.

The American people are asking if he is safe, or will be safe, to perform his duties as executive in chief. It’s a question that is as much about competency (our assessment of performance) as it is about competence (a legal standing to make decisions on behalf of himself or others).

Consider a similar scenario in which Sen. Diane Feinstein’s competency was in question when she was confused at a budget vote and instructed by handlers to just say “aye,” versus her competence in her own legal and financial affairs when her daughter activated power of attorney (over a sitting senator). Can someone who cannot govern themselves govern a nation? This same question is now core to the concerns challenging President Biden’s campaign.

To understand the situation, it’s important to realize that someone’s diagnosis doesn’t necessarily predict anything about a person’s function at any given moment – or for any given activity. Defenders of Biden are correct when they offer platitudes like “age is just a number.” Yes, age is just a number. Biology, however, is more than that.

Maine has the oldest population by median age, but our people are built tough – just consider Virginia Oliver, of Rockland, the 104-year-old lobster lady.

In medical practice, we often remark on whether or not a patient “looks their stated age,” because it tells us if their body is keeping up with them, or if time is outpacing their body. Those features of function are really what people are trying to ascertain about our president.

We need to separate questions of what is going on (disease) from how well things are going on (function). The latter is what the president and his medical team should be addressing clearly and openly; it’s the nearest we might get to an official statement about his competence and competency to carry out his duties. It is important to know in what ways, if any, he is compensating for impairments. So far, White House spokespeople have been cagey on just such information.

Let me explain why disease and function are related but not always congruent domains, and why we should be demanding for more information about the latter.

For example, the overaccumulation of two key proteins clumping together in the brain, with signs of shrinkage and damage in a particular pattern, are the criteria we use to diagnose a person with Alzheimer’s disease. Alzheimer’s disease is very common – about 1 in 9 people aged 65 years old or older has it (keep in mind the average age of the U.S. Senate is just shy of 65). A person may be diagnosed with Alzheimer’s, but the range of functional impairment initially varies widely, as can rate of decline and activities most affected. Diagnoses like Alzheimer’s and Parkinson’s disease are categorical definitions (you have it or you don’t). They tell you what is going on, but they don’t tell you how a person is getting along.

To evaluate performance, a different spectrum is used by doctors to grade a person’s dysfunction – regardless of the source of that dysfunction.

Subjective cognitive impairment means a person experiences cognitive difficulties noticeable to them (difficulties that have not caused them to give up specific activities of daily living like cooking, cleaning, driving, bill-paying and medication monitoring) but a doctor cannot find any evidence of impairment in cognitive tests.

Mild cognitive impairment is when patients experience difficulties that also do not result in the suspension of any such activities, but doctors do find deficiencies on cognitive testing.

And dementia is when there are difficulties that result in loss of one or more activities, and a doctor can find evidence of deficiencies on cognitive testing, too. That means a person can have Alzheimer’s disease but not have dementia. It is true that some diseases of cognition, like Alzheimer’s, do eventually progress to dementia, but the pace, duration and pattern of impairments can vary.

So that’s the first lesson to consider when approaching a candidate’s cognition. The cognitive testing that pundits are clamoring for – and no one has clearly specified what kind of cognitive testing is being sought – might at most put the president in a functional category in the broadest sense. It still wouldn’t automatically tell us anything about his function in specific tasks and domains.

The kind of judgment call we’re looking for is a judgment not about competence but of competency. No one is yet claiming the president is in such a state that he cannot govern his own affairs. He is competent in the medical-legal sense. However, there are certain self-determinations about one’s performance that are competence-related with medical-legal consequences that doctors can directly determine, like the revocation of a driving license in those judged to be cognitively impaired drivers.

Perhaps this is the closest metaphor for what the public is trying to get a sense of. Is President Biden safe to steer the country? His medical team may be the people best poised to alleviate or confirm the public’s concerns and keep the country safe. It seems that is the exact information we are not getting any time soon – except indirectly.

Biden and his medical team should work to produce a transparent and comprehensive articulation of his abilities as it pertains to the key tasks of the job he is pursuing and whether he can do those with or without occupational limitations. That is no different than what we would do for anyone “returning to work” or “needing to sign off” in the workplace when concerns about their health or function are raised.

There will be naysayers who will look for anything – from these doctors’ political contributions to their medical schools – to discredit a positive or negative assessment.

We don’t need to know categorical diagnoses or functional classifications; those are private matters. We especially don’t need raw results from cognitive tests. What will the public or pundits ever do with that?

What we need addressed is competency – and a medical opinion of occupational limitations, if any.

If Biden and his team refuse to lay the case out to a concerned American electorate, it’s like a patient who refuses to take a driving test despite his family’s concerns. The patient shows he has good judgment by giving up driving voluntarily – or proves his bad judgment with his refusal.