It is not difficult to see why the application of evolutionary theory to the processes of social change was attractive to people in the last half of the nineteenth century. Faith in science as a guarantor of social progress was widespread, and here was a scientific theory which seemed to confirm that belief. Auguste Comte, Herbert Spencer and to some extent Darwin himself all held that human society, like Nature, was inevitably advancing in a positive direction. The nineteenth century in Spain was marked by political and social instability; the process of industrialisation there lagged far behind that of Spain's European neighbours, as did the levels of infrastructure. It was therefore not surprising that the painful processes of change endured by the nation came to be viewed as part of the country's evolution into a prosperous and modern European state. Some people from modest backgrounds were creating their own wealth and the nature of Spanish social classes inevitably changed as well. As elsewhere, the newly moneyed classes in particular were keen to embrace the concept of evolution, as it seemed to validate their financial and social advancement, even if the process did not did not favour everyone. Peter J. Bowler confirms that the European bourgeoisie were in general only too happy to adopt social Darwinian ethics:

Spencer merely naturalized the moral values that the middle class had at first tried to justify by religion. Nature now became God's agent for rewarding the liberal virtues of thrift and enterprise.

Although this brand of social theory is commonly termed ‘Darwinian’, it really owes more to the work of Lamarck, as his theories were more open to this line of interpretation by social theorists. L. J. Jordanova comments,

Lamarck offered psychologists and social theorists ways of linking the physiological, mental, and cultural aspects of evolution, as he had done for Spencer. The notion of habit Lamarck employed could provide a biological account of the processes the nascent social sciences were seeking to explain, such as the progress of civilisation or the development of the human races.