In the present paper I attempt an interpretation of Martin Heidegger’s analysis of animality, developed in winter semester 1929/1930. My general purpose is to examine Heidegger’s analysis in the wider context of formal-indicative phenomenology as such. Thus I show that in order to develop a phenomenology of animality, Heidegger must tacitly renounce the re-enactment of animal experience in which the formal-indicative concepts of his analysis could gain concreteness, and he resorts instead to scientific concepts and concrete experiments in biology or (...) zoology. This is due to the fact that what I call the a-logical bursts into the field of the phenomenological regard when it is oriented toward animality. I therefore argue that the phenomenology of animality presents us with a paradigmatic case of a tension that is at work in any phenomenon, one between logos and a-logos, between hiddenness and unhiddenness—constituting a basic problem of future research in phenomenology and its approach to intersubjectivity and alterity. (shrink)