In this commentary, we argue that Phillips et al.'s findings can be used to provide new important insights in the debate between externalists’ theories of cognition. In particular, we claim that the results presented in this target article may offer us the conceptual palette needed for a sustained defence of an extended account of cognition over an enactive one.

The microbiome is proving to be increasingly important for human brain functioning. A series of recent studies have shown that the microbiome influences the central nervous system in various ways, and consequently acts on the psychological well-being of the individual by mediating, among others, the reactions of stress and anxiety. From a specifically neuroethical point of view, according to some scholars, the particular composition of the microbiome—qua microbial community—can have consequences on the traditional idea of human individuality. Another neuroethical aspect concerns the reception of this new knowledge in relation to clinical applications. In fact, attention to the balance of the microbiome—which includes eating behavior, the use of psychobiotics and, in the treatment of certain diseases, the use of fecal microbiota transplantation—may be limited or even prevented by a biased negative attitude. This attitude derives from a prejudice related to everything that has to do with the organic processing of food and, in general, with the human stomach and intestine: the latter have traditionally been regarded as low, dirty, contaminated and opposed to what belongs to the mind and the brain. This biased attitude can lead one to fail to adequately consider the new anthropological conceptions related to the microbiome, resulting in a state of health, both physical and psychological, inferior to what one might have by paying the right attention to the knowledge available today. Shifting from the ubiquitous high-low metaphor (which is synonymous with superior-inferior) to an inside-outside metaphor can thus be a neuroethical strategy to achieve a new and unbiased reception of the discoveries related to the microbiome.