The absence of relevant experience is one thing, the continuing impact of inappropriate and unhelpful experience quite another. The fact that Trump's life has been dedicated to his own self-advancement leads to concern that he is not just lacking the necessary qualities but that he is actually handicapped as he takes office, by allowing his experience to have taught him the wrong lessons.
The early indications, even before his inauguration, are not encouraging. He has already been exposed, by some immediate and pressing issues, as being ill-prepared for the major responsibilities that will soon become his.
It was surely unwise, and unlikely to build confidence, to have parted ways so publicly with his providers of intelligence.
His rejection of the briefing he has been given by the FBI, and the breakdown of relations between them, means that the US no longer has an accepted and reliable source of information about the activities of hostile interests - and the fact that the rejected briefings involve President Putin and Russia can only increase anxieties about the role they may have played in Trump's election.
And his child-like susceptibility to flattery, so expertly exploited by Putin,
is far from desirable in the man to whom the free world entrusts its future.
The nature of the allegations made against him - that the Russians have "compromising" material of a sexual or financial nature or both that could be used to blackmail him - and his difficulty in shaking himself free of this story, show how much his public image has already been damaged by what he revealed about himself during his election campaign.
There can be few who have ascended to high office under such a cloud of their own making.
In domestic politics, too, he has already shown himself to be less than sure-footed.
He seems to have struggled to comprehend that running the country is different from running his own businesses and that the two must be separated - indeed, it isn't clear that he sees any difference between them.
There is also, of course, the persistent impression - not helped by his continued refusal to publish his tax returns - that those businesses are in trouble and that they owe vast sums of money.
His record in business does not help.
It is one marked by risky borrowing, followed by repeated bankruptcies, leaving the burden of unpaid debt to be borne by the lenders - hardly likely to inspire confidence if (as he advocates) the same practices are applied to the management of the public finances.
And, in the appointments he has made to some of the most important offices in his Administration, he seems to have followed the principle that the essential qualification is that the appointee has a record of opposition to the interests (such as climate change or an end to racial discrimination) to be overseen.
Most worryingly, Trump's life experience appears to have taught him that celebrity and headlines are all that matter and will cure all. It seems we are about to enter an era of government by Twitter.
A snap overnight response to some perceived slight is apparently to replace careful analysis and considered policy - and opponents and those who disagree with him are to be countered by insults and scant regard for the truth.
It is hard to see that such an impetuous and narcissistic approach to government can possibly succeed. It is even harder to discern the likely end point.
No American president, surely, has ever entered the White House so much behind the eight ball before he has even begun. Oh, American voters, what have you done?
