Redistributionist inclinations dominate contemporary democratic politics, and show no signs of weakening. Ostensibly, the reasons for this are a desire for fairness, while its critics, and there are very few, tend to suggest that such claims are a cloak for self-serving envy. However, such criticism is easily deflected, since it is not hard to show that many, perhaps most, of those who call for high levels of taxation and public spending do not stand to benefit directly from these measures, at least not more so than any other member of the general public. Further, they may often be much affected by the measures that they demand. I can think of several well-off friends who honestly express the desire to pay more in tax.

Yet the charge of envy persists, perhaps because it seems to describe some part of the tone rather than the content of redistributionist demands, however moderate or self-wounding. Perhaps, in spite of appearances, there is something in it.

It is certainly true that only the most saintly do not experience a brief shooting sensation of distress at the achievements and success of others, particularly those close to us, whether friends or blood relations. We learn to suppress the outward and even the inward evidence of such feelings, but the traces are present nonetheless, though much easier to observe in others than in ourselves. I suggest that this envy is the emotional correlate of an awareness that another person has some degree of comparative advantage over us. We find this distressing because success in any endeavour matters much less than comparative failure. In other words, in any competitive situation, if we cannot exceed the achievement of our competitor, we prefer to see them on a level with us, even if that entails an absolute reduction in our own level of welfare. This is not careless spite, pure and simple, where we may harm ourselves very badly in order to hurt another. It is calculated spite, where we aim to reduce the comparative advantage enjoyed by another, and will accept a reduction in our absolute wellbeing as the necessary price.

A fictional example may demonstrate the concept. Imagine two apes beneath a large fruit tree that they cannot climb because of thick thorns round its base. The branches are high above their heads, and loaded with fruit, but with an athletic jump it is possible to pick some of the fruit, and this occasionally shakes other pieces of fruit from the branches.

One ape can jump rather better than the other, and succeeds where the other fails, though his efforts sometimes dislodge fruit that falls to the ground where it is taken by the weaker ape. Both are better off, but the good jumper obviously has the pick of the fruit, gets more, and is now at an advantage.

Conscious of his relative failure, the weaker ape surreptitiously snaps a few of the thorns and scatters them on the ground, so what when his friend lands after one of his attempts to seize some fruit he injures his feet and can jump no more or cannot jump as high or as often.

The weaker ape feels that this is beneficial, since though both are now fruitless, the stronger creature has no relative advantage. In addition, although it cannot be picked at present the fruit remains available, so the weaker ape has preserved his option of obtaining better access to the fruit at some time in the future.

The analogy with human politics should be clear. Politicians and economists might urge tolerance of the financially successful, the high leaping ape, on the grounds that a system which creates opportunities for such wealth disparities also creates general wealth and a higher level of average wealth. But such urgings are in vain; the rich are nonetheless resented.

It is tempting to suggest that this is an irrational response, and that we should recognise that wealth disparities bring about an increase in our absolute wealth (or at least so it is argued). However, I suspect that the emotion of envy is the product or at least the accompaniment of an accurate intuition of comparative disadvantage, to which we are extremely sensitive since our psychologies have been shaped by biological evolution driven by differential reproductive success. We are here today because of the relative reproductive success of our ancestors, not reproduction beyond an absolute threshold.

There is, I recognise, no certainty that these evolved psychological intuitions still reflect our reproductive interests today; we may be maladapted to current circumstances. However, we appear to be well adapted in many other respects, and given this it is not unreasonable to assume that the resentment of comparative advantage is still an adaptive response. At any rate, it appears to be a real response, adaptive or not.

I propose that this, probably rational and adaptive, resentment of relative success accounts for the powerful pressure in even very rich societies, and perhaps particularly in such societies, for the redistribution of wealth, largely through taxes on the rich, and benefits and public spending in the common interest.

On this view, the value of such taxes to those who advocate them is not so much in the redistribution or in the public spending itself, though doubtless there are some who gain much from both, but rather that the process of taxation erodes wealth differentials. Indeed, the fact that critics of tax-and-spend policies find it so difficult to turn to political advantage the manifest waste, gross inefficiency, and lamentable ineffectiveness of public services, indicates, to me, that the utility of the policy is elsewhere and beyond the reach of these attacks. That is to say, benefits to the poor and public services are beside the point, which is the punitive effect of taxation and the consequent economic levelling.

This, then, is the explanation of the otherwise very surprising erosion of economic liberty in democracies, a hallmark of the last two centuries. When we have our will, and we largely do in the democratic West, we wish for more equal distribution of wealth even at the cost of absolute wealth, and we do this not out of altruism, however much we may pretend that this is so, but out of a powerful and probably rational abhorrence for being at a comparative disadvantage.

In non-democratic systems the effects are reversed; force is employed to secure comparative advantage over others, and the compliance of the subordinate agents of force is secured by the offer of a compensating and ever growing sense of advantage, sometimes real and sometimes merely honorific, over those further down in the hierarchy. Each tier is allowed to feel itself an increasingly big fish in its own little pond. But this is inherently unstable since it requires constant growth in the perceived differentiations. This dynamic process is itself dependent on economic growth or the acquisition of wealth by conquest, for honorific tokens of hierarchical superiority, titles and gongs, are not in themselves sufficient or sufficient for long; some advantage must be economically real. Furthermore, without economic growth the lowest tiers in the system will be at a significant absolute disadvantage, lack of food for example, and this may be sufficient to provoke rebellion.

Democratic systems, by contrast, can be fairly stable and economically free so long as they are relatively poor in the absolute sense, since differentials in wealth will be low. With economic growth wealth differentials will also grow, and so will a corrosive sense of relative disadvantage, and with that a growing demand for taxation even at the cost of greater absolute average individual and aggregate wealth.

Growth and punitive taxation are, on the view I am currently arguing, closely linked, one actually leading to the other, since growth results in greater disparities of wealth, and these are perceived, largely correctly I think, as being genuinely threatening to the interests of those at a relative disadvantage. Since taxation acts as a brake on economic growth, an equilibrium results, with low growth and creeping taxation in balance, as it is in the developed world today.

Such 'fairer' societies may well be happier, as Wilkinson and Pickett seem to suggest in their strikingly popular study The Spirit Level (2009). But this contentment is bought at the cost of overall absolute wealth and, thus, in spite of a more cohesive or co-operative population, at the cost of long term security. For in spite of appearances, the desire for a more equal society springs not from altruistic or collectivist inclinations, but from an individually selfish and entirely rational insistence on low wealth differentials that as an accidental byproduct reduce aggregate societal wealth and sophistication and thus makes that society both less effective in competition with other groups and less robust in the face of natural disasters.

It is difficult to see any politically viable way of resolving this problem.