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“Modern economics, by which I mean the style of economics taught and practised in today's leading universities, likes to start the enquiries from the ground up: from individuals, through the household, village, district, state, country, to the whole world. In various degrees, the millions of individual decisions shape the eventualities people face; as both theory, common sense, and evidence tell us that there are enormous numbers of consequences of what we all do. Some of these consequences have been intended, but many are unintended. There is, however, a feedback, in that those consequences in turn go to shape what people subsequently can do and choose to do. When Becky's family drive their cars or use electricity, or when Desta's family create compost or burn wood for cooking, they add to global carbon emissions. Their contributions are no doubt negligible, but the millions of such tiny contributions sum to a sizeable amount, having consequences that people everywhere are likely to experience in different ways. It can be that the feedbacks are positive, so that the whole contribution is greater than the sum of the parts. Strikingly, unintended consequences can include emergent features, such as market prices, at which the demand for goods more or less equals their supply.

Earlier, I gave a description of Becky's and Desta's lives. Understanding their lives involves a lot more; it requires analysis, which usually calls for further description. To conduct an analysis, we need first of all to identify the material prospects the girls' households face - now and in the future, under uncertain contingencies. Second, we need to uncover the character of their choices and the pathways by which the choices made by millions of households like Becky's and Desta's go to produce the prospects they all face. Third, and relatedly, we need to uncover the pathways by which the families came to inherit their current circumstances.

These amount to a tall, even forbidding, order. Moreover, there is a thought that can haunt us: since everything probably affects everything else, how can we ever make sense of the social world? If we are weighed down by that worry, though, we won't ever make progress. Every discipline that I am familiar with draws caricatures of the world in order to make sense of it. The modern economist does this by building models, which are deliberately stripped down representations of the phenomena out there. When I say 'stripped down', I really mean stripped down. It isn't uncommon among us economists to focus on one or two causal factors, exclude everything else, hoping that this will enable us to understand how just those aspects of reality work and interact. The economist John Maynard Keynes described our subject thus: 'Economics is a science of thinking in terms of models joined to the art of choosing models which are relevant to the contemporary world.”
― Partha Dasgupta, Economics: A Very Short Introduction