The wealth of a country is more than the sum of the wealth of the individuals in it. When times get hard, the wealth of a person may be important but general societal infrastructure, housing, clean water, and the health and social safety net are particularly important. All these factors are linked to the wealth of the country, the distribution of wealth and the investment in a social safety net. It is clear that the health impact of the wealth of the individual is constrained by the wealth of the country - unless they are super rich or super poor. It is also clear that individual wealth is a very different animal from the wealth of a country. They are governed by different rules and indeed they have different names - an individual cannot have a gross domestic product.

Social capital is similar. There are good arguments for considering it at an ecological or an individual level. Just like the wealth of a country or an individual, the concepts of ecological and individual social capital are very different, and using the same name is confusing.

Mr Webber, Professor Huxley and I agree that social capital is the embedded resources of a society such as civic institutions. This is social capital at an ecological level. We would agree that different individuals in the same geographical area may have differential access to this social capital by way of their places in society or social relations. The sum total of social capital that they have access to is limited not only by their ability to get it, but also by the total amount that is available in that area. In addition, differential ability to get social capital is partly a function of the individual but is significantly constrained by the structure of the society that the individual lives in.

The challenge to those who consider social capital at an individual level is to answer the question: what is the added value of conceptualising and renaming social networks as social capital (Reference McKenzieMcKenzie, 2003)? They also have to consider whether they are measuring what social capital is or measuring how it is acquired.

It is confusing to define social capital both as the amount of resources potentially available to anyone in society and as an individual's ability to access such resources. Moreover, linking ecological and individual variables is fraught with difficulty - classically, the ecological and atomistic fallacies.

Although I argue that another term should be used for individual social capital, I think that these arguments take energy away from what should be the focus of the endeavour which is to improve our ability to describe our social worlds.

I have used the term social capitals previously to describe different types of ecological social capital in an area (Reference McKenzie, Whitley and WeichMcKenzie et al, 2002). Using the plural underlines the fact that there are different dimensions of social capital in an area and that the linear scales that some use, so as to label an area high or low in social capital, do not reflect the complex nature of social capital. Areas are better considered dimensionally along the lines of their different social capitals, such as bonding, bridging, vertical, cognitive, structural or social efficacy or cohesion. Such a taxonomy of social capitals could be expanded to include varieties of individual social capital as long as the caveats above have been taken into account.

I do not suggest that the variables that some researchers call individual social capital not be measured. I have, however, suggested that they should be accurately described and named. Perhaps the way forward is to clearly state what is being measured in studies and why, rather than making a further leap to say that proxy measurements reflect social capital which is, of course, a theory that is still in development.