The Future Is Not What It Used to Be

On predictions, judgement, and the art of acting without certainty.

Friday, 13 November 2026 occupies a curious place in the history of science. In 1960, Heinz von Foerster and his colleagues published an article in Science identifying that very day as the moment when, according to their model, the world’s population would approach infinity.

This was a mathematical singularity, rather than a literal vision of infinitely many people. Yet the date gave the calculation a striking precision. An uncertain future had been given an appointment in the calendar.

On 8 October 2026, Science published Javier A. Birchenall’s retrospective on this prediction. There was still just over a month to go before the foretold day. We should therefore be precise: the date has not yet passed. Nevertheless, population trends have already diverged sharply from the trajectory described by the model. Birchenall estimates that the world’s population will be around 8.3 billion on the old doomsday date. It is still growing, but the rate of growth is declining.

The future is not what it used to be. Perhaps this says as much about our expectations as it does about the future itself.

It is tempting to use this story to laugh at scientists who got things wrong. We should resist that temptation. The model was neither arbitrary nor without value. It captured a real acceleration in population growth and described developments well for a time. The error arose when a historical pattern was given the status of a permanent law.

That distinction is crucial. Something can be true of a particular period without being true for all time.

In the middle of the twentieth century, rapid population growth could look like a movement that would only gather momentum. But human societies change. Patterns of childbearing, living conditions, and people’s choices are part of the developments that demographic models seek to describe. Eventually, the model lost its grip on reality.

What had appeared to be an inevitable future turned out to be the experience of a particular era.

This is where practical philosophy begins. It asks how we should live and act when our knowledge is limited. We cannot wait for complete certainty before choosing an education, having children, building a society, or taking responsibility for others. Life demands decisions long before all the facts are available.

In Aristotle, we find the concept of phronesis, usually translated as practical wisdom. It involves judging what a situation requires, with attention to experience, circumstances, and the good we hope to achieve. A rule or a calculation can help us, but it cannot take over our responsibility for making that judgement.

The history of the population model illustrates why. A calculation can be correctly performed and still provide a poor basis for action if its assumptions no longer hold. Practical wisdom therefore involves asking: What must remain true for this forecast to be useful? What suggests that the situation has changed?

Such questions also apply to our private lives. We may go through a difficult period and turn it into a prediction: this is how things will always be. We may succeed a few times and begin to take continued progress for granted. In both cases, we extend an experience into a future we do not yet know.

A moment becomes a destiny.

This does not mean that we should stop planning. It means that good plans need room for revision. Someone considering an education must take the labour market into account, but also ask which skills will remain valuable if the forecast proves wrong. Someone building a business needs expectations about demand and economic conditions, but also the ability to change course.

In practice, a decision can be wise even if the future turns out differently from what we expected. It can develop our abilities, preserve our freedom to act, and leave us better equipped to face several possible outcomes.

Birchenall also shows how easily the story can reverse. While earlier decades feared explosive population growth, many people now worry about low birth rates and population decline. If Japan’s current rate of decline is treated as an eternal law, it is possible to calculate a distant date when the country will be emptied of people. The article uses 5 May 3108 as an illustration.

The point is not that this date should be taken seriously as a forecast. The point is how easily we repeat the old mistake in the opposite direction. Once, the curve rose towards infinity. Now, it can be projected towards emptiness. In both cases, we allow today’s trends to have the final word on every tomorrow.

The dates make this particularly clear. The years 1960, 2026, and 3108 belong to very different time horizons, yet a precise calendar date can lend them an appearance of equal certainty. We must distinguish between the precision of a calculation and the certainty of its assumptions.

Still, the failure of a doomsday model does not mean that all warnings are exaggerated. Population pressure can create real problems without the population approaching infinity. Low birth rates can pose difficult challenges for society without a country becoming uninhabited. Criticising the endpoint of a prediction does not relieve us of the need to consider the problems along the way.

Taking uncertainty seriously therefore requires more than scepticism. We must weigh what we know, the possible consequences, and the costs of waiting. Some actions can be revised. Others have consequences that are difficult to undo. Practical wisdom takes this difference into account.

The errors of research into the future do not, then, teach us that knowledge is worthless. They remind us that knowledge must be used with judgement. We need models, but also the willingness to recognise when the world no longer follows them.

The future is not what it used to be. Nor is it simply what we now calculate it will become. It will contain events we have not foreseen and choices that have not yet been made.

We can meet it with firm convictions that remain open to questioning, plans that allow for change, and a sense of responsibility that does not depend on certainty. This may be one of the most important things practical philosophy can teach us: to act thoughtfully and with care, while remembering that we may be wrong.

Source: Javier A. Birchenall, “Demographic ‘doomsday’ misses the mark”, Science, 8 October 2026, pp. 173–174. This essay draws on the article; the philosophical reflections are independent.