In Social Limits of Growth (1977), Hirsch suggests that, as societies become richer, many of the extra goods, services and facilities sought by consumers cannot be acquired or used by all, without spoiling them for each other: ‘what each of us can achieve, all cannot’. Thus as pointed out by Mishan (1967): ‘The tourist in search of something different, inevitably erodes and destroys that difference by his enjoyment of it.‘According to Hirsch, ‘our existing concept of economic output is appropriate only for truly private goods, having no element of interdependence between consumption by different individuals’. Many of the environmental issues – problems of congestion, pollution, etc. – which increasingly arise in modern industrial societies, involve positionality in Hirsch's sense. The need for a distributional morality to support a limit to growth is emphasized by Hirsch. This view contrasts with the technocratic optimism usually associated with economist's theories of economic growth. see also PUBLIC GOODS.