The most important equilibrium in research isn’t chemical, it’s psychological. It’s the one that governs the oscillation between confidence and doubt.

Confidence, and doubt. The two essential but utterly antagonistic poles of the scientist’s mind. To have one without the other is to be doomed to underachievement, and possibly failure. But to live with both means to be forever pulled in two directions.

Consider the first. The advantages of confidence are obvious. With confidence in yourself, it’s easier to step outside your comfort zone, take risks, and defend a position in the face of criticism. With confidence, it’s easier to find the courage to make bold proposals, and to strike out into the unknown.

But to have only confidence is to become Macbeth*. Overconfidence is as much of a confidence problem as having no confidence at all. It is to be so sure of yourself that you blind yourself to alternative interpretations – and sooner or later, Birnam Wood and Macduff will come knocking at your door. Confidence alone can carry you a long way, but its very surety – in scientific terms – is a handicap in itself.

Overconfidence need not only hamper us at the bench. Coriolanus**, another of Shakespeare’s tragic heroes, offers the parable of political overconfidence. For all its desire for objectivity, science remains a human activity carried out by human beings, and even a genius-level intellect will come undone if its faith in itself translates into hubris towards those around it.

Consider the second. It is doubt, not confidence, that truly defines the scientist. In the priesthood, to entertain doubt is to court heresy; in science, it is doubt that makes you orthodox. To be a scientist is to question everything around you, including the oldest and most cherished dogmas. It is to question yourself. It is to swim, perpetually, in oceans of doubt.

But to have doubt only is to drown. That essential scepticism, directed unremittingly at the self, can sink the strongest vessel. Concern over data quality, over interpretation, over the right to continue, over one’s own self-worth – such is the outcome of doubt expressed without any counteracting force.

These, then, are the two opposing forces that must struggle in the scientist’s mind. Pretty much all of us are familiar with the emotional rollercoaster that is entailed by a life in research – the effervescent highs when confidence is firm and doubt vanquished, and the crippling lows when doubt rules and success seems impossible. It is a painful truth that this very rollercoaster is the defining feature of a creative occupation, common not just to scientists but writers, directors, actors, and more. To exist in science is to place oneself forever in the middle of that equilibrium, and to struggle to stay there.

*Macbeth receives a series of enticing prophecies from a trio of witches and uses them to justify a bloody usurpation of power. Every prophecy is true, but Macbeth consistently misinterprets their real meaning and ends up damning himself.

**Coriolanus is a Roman general whose successes on the battlefield create a sense of entitlement in the political arena. He refuses to treat his peers humbly, and is cast out.