This chapter focuses on what is arguably nineteenth-century Spain's greatest contribution to philosophical debate about wrongdoing, and to natural philosophy more broadly: the work of Dr Pedro Mata (1811–77), Chair of Legal Medicine in Madrid from 1843 to 1874. The essay centres on the intellectual implications of Mata's ways of thinking about the workings of the brain and what they tell us about our responsibility for our own actions. Mata's arguments amount to a series of bold claims. Rather than appealing to some governing, executive, conscious subject that would be accountable for our actions, Mata looks instead only to the multifarious interactions of different parts of the brain and body. He sees reasoning and decision-making as something involving much more than an intellectual process. He argues that study of our biology is sufficient to provide us with normative criteria for judging whether someone is responsible for their actions. He sets out an ethics within natural philosophy which combines universal applicability with an inevitable diversity in modes of thought. Mata's wide-ranging work and rich life, political as much as academic, have been studied in relation to the historical development of nineteenth-century Spanish society and culture. He figures in monographs on medical philosophers, for example (Carreras y Artau 1952 was a seminal study). His works have been usefully summarized in their immediate context, for instance in María Nieves López Fernández's account of his views on psychology (1993). Richard Cleminson and Francisco Vázquez García have made striking use of his work and influence in explicating how Spanish medical science understood sexual identity and related legal issues during the century (2009: 89–96). The emphasis of this present essay lies elsewhere: in exploring Mata's ideas in relation to ongoing debates, putting them into play with more recent philosophers. Above all, I seek to draw out here what specifically makes Mata's thought a compelling contribution to natural philosophy and to our understanding of moral and legal responsibility. At the heart of all this is Mata's understanding of states and functions of the brain.

Mata was a hugely influential individual in the development of thinking about wrongdoing and criminal responsibility in the Spain of his time. He founded his university's curriculum in legal medicine, and authored a standard Spanish textbook on medicine in law which ran to six editions by 1903, updated by other authors.