What we call the centre, and why it is hard to locate

In the first sense, the centre is a statistical point: the mean or median position of people on a given dimension. That centre always exists, but it shifts with the population measured and with the dimension chosen. It has no ideological substance of its own, since it is only a positional landmark.

A known consequence of this sense is the median voter reasoning, formalised by Anthony Downs: in a two-offer competition on a single dimension, the offers have an interest in moving towards the middle. The reasoning weakens as soon as dimensions are added, which is the real case.

It also weakens as soon as mobilisation is taken into account. Moving towards the middle may win over the undecided and lose convinced supporters, which changes the calculation: the optimal position is not the one that pleases the greatest number, but the one that maximises the votes actually cast.

In the second sense, being in the centre describes a preference for balance between competing values, or a distrust of single solutions. It is a position of content, which can be argued for and which is in no way an absence of position.

That centre is not necessarily in the middle of the scales. A person may be very clear-cut on several dimensions and claim a cautious method of arbitration, which produces a marked profile with a moderate discourse.

It has an intellectual coherence of its own: favouring reversibility, distrusting reforms that cannot be undone, preferring adjustments to ruptures. These are debatable principles, but they are indeed principles, and not the refusal to have any.

In the third sense, the centre is defined in relation to the other offers available: whoever stands between the others is in the centre, whatever their content. That centre therefore shifts when the others move, without its positions changing.

It is the sense most used in political commentary, and the most slippery. It allows the same position to be described as central in one period and off-centre in another, without any conviction having varied.

The same person may be at the statistical centre and reject the label, or claim the centre while holding positions far from the average. Commentaries announcing a majority centre generally rely on the first sense, those announcing it nowhere to be found on the third.

Distinguishing the three settles no debate, but it avoids discussing three things at once. It is the condition for the conversation to bear on positions and not on a word.

The useful question is not “am I in the centre” but “on which dimensions am I close to the average, and on which do I depart from it”. Almost nobody is in the middle everywhere, and a profile announcing as much deserves to be reread in the light of the speed at which it was filled in.

A person genuinely central on every dimension exists, but is rare, and above all is different from a person central on average: the second offsets clear-cut and opposite positions, the first has none.