Philosophy of biology is that branch of philosophy dealing with the major issues arising from biological sciences, such as the proper understanding of evolutionary processes, the demarcation between living and non-living entities, the nature of species and – more generally – of biological taxa. This variety of topics renders philosophy of biology a highly interdisciplinary terrain of research, at the intersections with the life sciences, metaphysics, or bioethics. Philosophy of biology emerged as a fertile and independent field of research only in the second half of last century. To date, some hundreds of scholars around the world work on issues in the field.
What Is Life?
What tells apart living from non-living entities? This has been a central question throughout the entire philosophical Western tradition. According to vitalists, living entities are made out of some substance that is not present in non-living entities: they called it "vis viva," literally "life force." Reductionists, on the other hand, claimed that living and non-living entities are not different in constitution, but only in internal organization.
The reductionist view gained plausibility in the 1930s, as biochemistry was being developed. Till then, it was clear that living entities do things that non-living ones do not: for example, they self-reproduce, self-regulate, and metabolize. But this evidence was invoked also by vitalists to show that life required a specific category of elements. It was in 1943 that the plausibility of reductionism started seeming apparent to the most: that is the year in which the Austrian physicist Erwin Schrödinger delivered seven lectures at University College, Dublin. The following year, the lectures were turned into a short volume: What Is Life? In an accessible text, Schrödinger knitted one of the most fascinating works in the recent history of science, which had a tremendous impact on the impressing development of life sciences.
Succinctly, Schrödinger’s main thesis is that "The most essential part of a living cell, the chromosome fibre, may suitably be called an aperiodic crystal. In physics we have dealt hitherto only with periodic crystals." (Chapter 1) That is, amidst several other witty remarks, Schrödinger conjectured that what sets apart living entities is the structure of the gene, which is aperiodic. He was right. And, ten years later, two scientists that were converted to biochemistry by Schrödinger’s work, showed that DNA is composed of the same elements composing non-living entities; also their findings showed that DNA has an aperiodic structure, as conjectured by the Austrian physicist.
So, the difference between living and non living entities may very well lie in a geometric property of the chemical structure of DNA: aperiodicity.
Understanding Evolution
Most publications and courses in the philosophy of biology deal with the proper understanding of evolutionary process. What is the role of chance in evolution? Who are the protagonists of processes of selection: species, populations, individuals, or genes? How do we know that a trait was specifically selected, rather than being accidentally linked to a trait that was selected? What is the origin of life? Can every trait be accounted for in evolutionary terms? These are some of the typical questions that philosophers of biology debate alongside with life scientists.
Kinds and Classifications
Aristotle already disserted at length over the correct classification of individuals into species. The contemporary system of classification was ideated by the Swedish naturalist Carolus Linneus (1707-1778) in his Systema Naturae. But it is with the affirmation of evolutionary theory that species became the protagonists of biology: if species evolve, how to we draw boundaries between them? Several thousands of scholarly publications have been in some way devoted this question over the past fifty years. From them depends our understanding of evolutionary history and biodiversity, for example.
The problem of classification expands well beyond species. Are higher biological taxa real or conventional? Or, think about the difficulties of classifying fruits and plants, plant varieties (e.g. the varieties of apples), animal breeds, and human races.
Further Topics
In a short time, Schrödinger’s suggestions lead to amazing results. By 1960 the different varieties of RNA had been detected. In 1961, Crick understood that amino acids are coded in triplets. In 1973, the first GMO was created. In 1980, the first patent on a GMO was issued. In 1983 Tom Cech and Sidney Altman showed, independently, that RNA can exist autonomously from DNA. In 2010 Craig Venter announced the existence of the first genetically engineered living entity (an entity whose DNA was artificially produced.)
The genetic revolution poses some of the most difficult dilemmas with management of science for governments and societies. Should we feed ourselves GMOs? Should we patent GMOs? Should we allow genetic engineering to be applied to humans? To what degree should researchers in life sciences have a vested interest in biotechnological companies?
Philosophers of biology have also worked on several other momentous issues such as the nature of races, the relationship between sex and gender, or the tie between nature and nurture.
The relevance of those questions to the general public at least partially explains the success that philosophy of biology has earned of the last few decades.
