Poverty is not just the absence of sufficient income or a level of consumption that is below a minimum threshold. Poverty is multidimensional: it also means bad health, high mortality rates, illiteracy etc. And these different elements of poverty tend to have a negative effect on each other (the so-called poverty trap). Being deprived of literacy or education is usually seen as an obstacle to material wellbeing.
The absence of material wellbeing – whether expressed in terms of income, consumption, health, mortality etc. – is often viewed as an isolated evil. However, it’s possible to make the case that it can also have psychological effects that harm people’s mental wellbeing. If this is true, and I think it is, then poverty does more harm than we usually think it does.
I believe it’s widely accepted that poverty does some psychological damage, such as stress, depression, loss of self-esteem and of the feeling of control, loss of ambition and aspirations etc. Although usually people assume – correctly or not – that this type of damage is less severe or less urgent than the physical damage that results from poverty (such as bad health, mortality, hunger etc.). Some even argue that there’s a tendency to overemphasize the link between material deprivation and (the perception of) subjective wellbeing, and that psychological problems which may seem to be caused by material deprivation have in fact other causes (genetics, upbringing, personality etc.).
However, I think the tendency is rather to underestimate the effects on mental wellbeing. A recognition of the psychological effects of poverty would also open the possibility of a more positive evaluation of notions such as poverty as vulnerability and relative poverty. Vulnerability, or a high level of risk of poverty, can perhaps produce the same amount of stress as actual poverty. And one’s self-esteem can suffer as much from actual deprivation (including illiteracy) as from comparative (or relative) deprivation (e.g. comparatively low levels of education or income).