President Biden walks off after speaking about the deteriorating situation in Afghanistan from the White House, Aug. 16.

Photo: Evan Vucci/Associated Press

As with many adventures in decolonization, the 1974 coup in Portugal that led to the independence of Angola and Mozambique worked out better for the colonizers than the colonized.

The Portuguese got an end to the Salazar dictatorship, a start down the road to democracy and modernity. Their African colonies got an exodus of most of their professional and technical experts, followed by an economic collapse and decades of violence and poverty.

Other colonial powers found at least somewhat less nakedly cynical ways of leaving. The British kept up Commonwealth ties with their ex-colonies; the French maintained many financial and institutional links. America’s departure from Afghanistan is a lot more like Portugal’s. However much Washington wants to see a failure of the Afghan state, the U.S. long ago became the state in Afghanistan. It supplied a social infrastructure Afghans were never likely to build on their own, pluralistic, wearing its Islam lightly.

True, 155 million Americans voted in 2020 for presidential candidates who favored withdrawal. Voters might or might not have felt differently if told a new truth. We weren’t just holding off terrorism. We had given half of Afghans (median age 18) the only order they ever knew. We had birthed an unlikely experiment in modernity that might prove useful in our long confrontation with militant Islam. Now we’ll never know.

President Biden at one time exhibited wisdom about a transitional presidency: “Look, I view myself as a bridge, not as anything else.” Then he discovered himself to be a transformative FDR-like president. He detected a sweeping mandate unseen by anyone except his White House toadies. (Perhaps it was tucked inside all those mail-in ballots.)

This week he’s back to being transitional, taking on himself the debacle of the Afghanistan withdrawal, which it was destined always to be, and relieving future presidents of this particular dilemma.

Mr. Biden willed this end. Give him this much credit at least. The shock at seeing on our television screens what his choice made inevitable would not be landing so hard, and prompting so many remembrances of an unflattering quote from former Defense Secretary Robert Gates, if Mr. Biden had not also incautiously guaranteed that America’s conspicuous surrender would somehow not translate into conspicuous chaos on the ground.

Was Mr. Biden running his mouth ill-advisedly, as his wont? The intelligence may have been bad. But even when throwing out excuses on Monday, he never pretended he wasn’t deliberately handing the country over to the Taliban, the inevitable consequence of his decision.

The unplanned debacle that came with this planned debacle goes to the continuing question of the strengths and limitations of Mr. Biden. If you want evidence of shrewdness, it’s not impossible to find. He gave himself an insurance policy in the 2024 nomination contest, sticking fellow Democrats with Kamala Harris as the likely alternative. Or take the White House’s ludicrous-seeming intervention in Hunter Biden’s painting career. Was this not a way of acknowledging the truth of the Hunter laptop without acknowledging it? By admitting the obvious, that everything the younger Biden does must be treated as an attempt to cash in on influence, his father made it safe for the mainstream media to continue covering up for him and his son. And so far the media has complied.

For millions of Americans, Mr. Biden was the closest thing to a conventional, confidence-inspiring authority figure in the 2020 race next to Bernie Sanders, Elizabeth Warren and Donald Trump. Sure, it was more a result of longevity and résumé than any personal qualities of a man who, when he started talking, once led a fellow senator named Barack Obama to pass a note to a colleague saying “shoot me now.”

Yet the torrent of criticism falling on him today is criticism for the inevitable and predictable consequences of a choice he made with eyes wide open. Mr. Biden knew the outcomes could only be bad. There’s a reason the U.S. kept at it for 20 years: The alternative always seemed worse, as events may prove (and soon if U.S. troops and the Taliban end up disputing for control of Kabul airport and evacuation flights).

But if being 78 years old is good for anything, it teaches that what’s a big deal today can be forgotten tomorrow. Mr. Biden was recently heard predicting a summer of freedom from Covid too. A wild card in his pocket is the apparent inability of the U.S. political system to throw up a candidate at the presidential level whom a broad swath of Americans can truly respect. Of course Mr. Biden would have to rethink everything if Donald Trump weren’t reliably spraying a blanket of herbicide over any worthwhile Republican field.

So a question sometimes asked about Mr. Biden doesn’t apply this time. When he consigned Afghanistan to its fate, he knew exactly what he was doing.

As thousands attempt to flee Taliban rule, Joe Biden tries to duck responsibility for his calamitous withdrawal from Afghanistan. Images: AP/Getty Images Composite: Mark Kelly The Wall Street Journal Interactive Edition