It is said that on a trip to the US in the 1920s a German sociologist was astonished at the domestic arrangements of his American colleagues. How can you get any serious work done, he asked, without servants? The duties of a spouse and parent apparently do not sit well with deep thought and research, unless eased by paid help.

This makes me wonder whether “parentism” might be a problem to consider alongside sexism, at least in certain branches of academia. The two often go together, but they need not. Consider the student parlour game of puzzling over who among the major philosophical thinkers had a conventional home life.

In the ancient Greek world, Socrates was married with children but never got round to writing anything down. Plato, as far as we know, never married. Aristotle did marry, and one of his major works, The Nicomachean Ethics, is named after his son. But in later centuries the record is astonishing.

One hypothesis is that domestic bliss dulls the philosophical edge

St Augustine (“grant me chastity, but not yet”) fathered an illegitimate child, but then became a celibate priest. Aquinas and the philosophers of the middle ages were all churchmen. In the 17th and 18th centuries, virtually all of the canonical figures were domestically unconventional. Hobbes, Locke, Hume, Adam Smith, Descartes, Spinoza, Leibniz, Kant and Bentham all went unmarried. Bishop Berkeley married late but had no children. Jean-Jacques Rousseau eventually married his lover Thérèse Levasseur, but abandoned all of his five children to foundling homes. This did not stop him writing a treatise, Emile, on the proper upbringing of children.

Closer to our own time, John Stuart Mill married late in life and had no children of his own. Schopenhauer, Kierkegaard, Nietzsche, Sartre and Wittgenstein were all unmarried and childless. Marx gave up philosophy, turning to economics and politics, when his children were still young.

There are exceptions. Hegel married and had children. And in the 20th century AJ Ayer and Betrand Russell brought up the averages by marrying lavishly, though reproducing modestly. But it is a remarkable tradition.

What about the major women philosophers? Of those who are widely known, Mary Wollstonecraft produced her major works before producing her children, and tragically died from complications after the birth of her second child, who would become Mary Shelley. Simone de Beauvoir, Hannah Arendt, Simone Weil and Iris Murdoch, were all childless.

What explains this extraordinary correlation? It could be pure coincidence, but other hypotheses press for consideration. One is that the sheer oddity of philosophers makes them unsuitable life partners. Another is that domestic bliss dulls the philosophical edge. A third is that the problem lies in the nature of the deepest, most fundamental, philosophical work. If genius is “the infinite capacity for taking pains”, it wouldn’t seem to leave much time for anything else.

Nevertheless, few are on the level of Spinoza or Kierkegaard. For ordinary mortals our research requires only a finite capacity for taking pains, which ought to be compatible with a normal home life. In fact, in a recent survey in my faculty, although many people report that they struggle to achieve an acceptable life-work balance, those caring for children seem to do better than those who are not. And this makes sense. If you are looking after your children it puts your academic work into perspective. Maybe it isn’t the most important thing in the world after all.

The trouble is that if you don’t think your research and writing are the most important thing, at least in your own world, you probably won’t do as much of it as you could. And this is how the academic careers of parents, especially mothers, can stall. Once upon a time, we would have said: “That’s the choice you make”. Now we know that there is such a thing as “indirect discrimination”. We need to define a new model of academic progression that is fair to everyone. And a start would be to make advancement dependent on what academics do during normal working hours, rather than in their evenings and weekends.

Jonathan Wolff is professor of philosophy at University College London and dean of arts and humanities