This paper takes a review of the central tenets of emergentist philosophies and a characterization of some varieties of emergentism as a starting point for treating one of the most controversial theses related to that philosophical doctrine, namely, the 'irreducibility' thesis. The main contention here is that the meaning of this thesis should be refined, if we wish to advance in the discussion about the senses in which one can say that emergent properties are 'irreducible'. Based on works by Stephan and colleagues, two modes of the irreducibility of emergent properties are distinguished, irreducibility as non-analisability and irreducibility as non-deducibility. A detailed analysis of the irreducibility concept leads to the following question: What does it mean to say that a given class of emergent properties is irreducible? We argue here that different classes of properties can be irreducible in different senses, and, thus, according to different modes of irreducibility. The paper discusses, in particular, the mode of irreducibility which holds in the case of properties of biological systems. We argue that emergent properties of biological systems are irreducible in the sense that it is not possible to deduce their instantiation in living systems of a certain class from knowledge about simpler living systems only. In other words, biological emergent properties are irreducible in terms of their non-deducibility, but they aren't irreducible in terms of their non-analisability. A clear understanding of the mode of irreducibility which holds in the case of biological properties makes it possible that the requisites for the demonstration of their emergent nature be more realistic, and the discussions about the prospects and limits of reductionism in biological sciences advance in a consistent manner.
Emergent properties; Irreducibility; Non-analisability; Non-deducibility; Reductionism; Emergentism
