Many teachers and students of philosophy today feel that the subject is under threat – not only from funding cuts, but from a more pervasive and less quantifiable cultural shift towards measuring value only in instrumental and monetary terms. But when we philosophers try to defend our discipline, the question of why philosophy is important sometimes gets entangled with our own self-importance. More to the point, perhaps, when we seek to protect philosophy we are also protecting our livelihood. There is an irony here, since philosophers often present themselves as thinkers who attain a supreme objectivity in relation to whatever issues they engage with.

I'm not suggesting that philosophers should give up insisting on the value of philosophy, or that our collective expertise in reasoning and in the history of philosophy isn't something to be proud of. But the question of our objectivity concerning the significance of philosophy gives us good reason to listen to Bertrand Russell's views on this subject. Russell was more than a philosopher: he was also a mathematician, a peace campaigner, an educator, a populariser of modern science and a cultural critic. The range and diversity of his work makes him well placed to comment on the value of philosophy, for he appreciated the relationship between philosophy and other kinds of inquiry. And Russell more than once showed himself to be committed to the pursuit of truth even when this jeopardised his professional life, or conflicted with his earlier work.

In his 1946 essay Philosophy for Laymen, Russell discusses the nature, purpose and importance of philosophy. He lists a set of questions that belong to philosophical inquiry: "Do we survive death in any sense, and if so, do we survive for a time or for ever? Can mind dominate matter, or does matter completely dominate mind, or has each, perhaps, a certain limited independence? Has the universe a purpose? Or is it driven by blind necessity? Or is it a mere chaos and jumble, in which the natural laws that we think we find are only a fantasy generated by our own love of order? If there is a cosmic scheme, has life more importance in it than astronomy would lead us to suppose, or is our emphasis upon life mere parochialism and self-importance?"

It is striking that Russell focuses here on the more "cosmic" questions of philosophy – questions that many would recognise as broadly religious as well as philosophical. Characteristically, Russell professes his agnosticism, stating that he cannot answer such questions and that he does not believe anyone else can answer them either. Nevertheless, he continues: "Human life would be impoverished if they were forgotten, or if definite answers were accepted without adequate evidence." One important purpose of philosophy, therefore, is to keep interest in these questions alive, and to scrutinise any answer that might be proposed.

Russell revives an ancient conception of philosophy as a way of life in insisting that questions of cosmic meaning and value have an existential, ethical and spiritual urgency. (Of course, what we might mean by such terms is another issue for philosophers to grapple with.) In the ancient Greek tradition, Russell reminds us, philosophy was not simply a theoretical exercise, and philosophers were not just – or not at all – professional thinkers. "Socrates and Plato were shocked by the sophists because they had no religious aims," he writes, and adds that many of the ancient Greek philosophers "founded fraternities which had a certain resemblance to the monastic orders of later times".

Socrates argues in the Republic that the philosopher's pursuit of truth involves reorienting his whole soul towards the good, as well as theoretical clarification of what the soul is and what its good consists in. Aristotle developed this idea through his virtue ethics, which shows how our characters can be formed, in practice, in accordance with what is good for us – our happiness and fulfilment as human beings. Russell stands in this tradition, arguing that "if philosophy is to play a serious part in the lives of men who are not specialists, it must not cease to advocate some way of life". He identifies key differences between philosophical and religious approaches to living well: philosophy refuses any appeal to the authority of a tradition or a sacred book, and the philosopher should not attempt to establish a church.

Russell evidently regarded authoritarianism as the essence of religion, and on this basis his philosophy is emphatically anti-religious. An ethically oriented scepticism lies at the heart of his own conception of a properly philosophical way of life. For Russell, philosophy should lead to peace – to personal serenity, and to peace in the world. "Dogmatism is an enemy to peace, and an insuperable barrier to democracy," he writes. Even minimal philosophical training, he argues, would teach us to see through the "bloodthirsty nonsense" preached in the name of nationalist, sectarian interests – and also, it should be added, in the name of democracy.

In his 1946 essay, Russell teaches his "laymen" readers to think more objectively about emotive issues: "When, in a sentence expressing political opinion, there are words that arouse powerful but different emotions in different readers, try replacing them by symbols, A, B, C, and so on and forgetting the particular significance of the symbols. Suppose A is England, B is Germany and C is Russia. So long as you remember what the letters mean, most of the things you will believe will depend upon whether you are English, German or Russian, which is logically irrelevant."

Of course, it is easier to master this kind of technique than to apply it in situations when it is most needed – at times of crisis, stress, or emotional turbulence. But this is precisely why philosophy is not just an intellectual exercise, but an existential task that – as Aristotle saw so clearly – requires patient practice. As Russell puts it: "To endure uncertainty is difficult, but so are most of the other virtues. For the learning of every virtue there is an appropriate discipline, and for the learning of suspended judgment the best discipline is philosophy."