Why does boserup suggest that population growth might be a good thing?

According to Malthusian theory, the size and growth of the population depends on the food supply and agricultural methods. In Boserup's theory agricultural methods depend on the size of the population. In the Malthusian view, in times when food is not sufficient for everyone, the excess population will die. However, Boserup argued that in those times of pressure, people will find ways to increase the production of food by increasing workforce, machinery, fertilizers, etc. This graph shows how the rate of food supply may vary but never reaches its carrying capacity because every time it is getting near, there is an invention or development that causes the food supply to increase.

Although Boserup is widely regarded as anti-Malthusian, both her insights and those of Malthus can be comfortably combined within the same general theoretical framework.[2]

She argued that when population density is low enough to allow it, land tends to be used intermittently, with heavy reliance on fire to clear fields and fallowing to restore fertility (often called slash and burn farming). Numerous studies have shown such methods to be favourable in total workload and also efficiency (output versus input). In Boserup's theory, it is only when rising population density curtails the use of fallowing (and therefore the use of fire) that fields are moved towards annual cultivation. Contending with insufficiently fallowed, less fertile plots, covered with grass or bushes rather than forest, mandates expanded efforts at fertilizing, field preparation, weed control, and irrigation. These changes often induce agricultural innovation, but increase marginal labour cost to the farmer as well: the higher the rural population density, the more hours the farmer must work for the same amount of produce. Therefore, workloads tend to rise while efficiency drops. This process of raising production at the cost of more work at lower efficiency is what Boserup describes as "agricultural intensification".

The theory has been instrumental in understanding agricultural patterns in developing countries, although it is highly simplified and generalized.