What is individuality: why care?

Biology seems like a prime example of how the conception of individuality - the choice of how to draw boundaries around an agent and its environment - is less straightforward, and more riddled with puzzles than appears to be the case at first sight. For example, we might start out with a naive conception that, obviously, biological individuality is one organism - an elephant, a monkey or a tree. Those are the units of replication (evolutionary theory) as well as the units of metabolism (biochemistry, ecology). However, it doesn’t take long until we run into trouble. Consider the relationship between an ant and an ant colony. A worker ant is not the unit of replication, and yet it lays a critical role in how an ant population propagates. Or consider fungus. What looks to us like “the fungus” is really only a small part of the entire, largely subterrestrial fungus web (called the mycorrhizal network). [more examples] This is to illustrate, the question of what makes for an individual is much deeper and more intricate than one might assume. 

Not so fast… sure, different biological organisms come in lots of different shapes and modes of organization. But is this entire talk of individuality not just a substance-less philosophical debate disguised behind smart-sounding semantics? I think not, but I will need some space to explain why. 

First, it can be useful to notice the sheer ubiquity of the use of (different) notions of individuality in scientific theory across basically any field of study. In particular, the usage of the notion of individuality - or, more pragmatically, decisions about how to draw boundaries between agents and their environments - often play load-bearing roles in those theories. For example, individual agents (be that in biology, psychology or economics) usually represent the unit of analysis. The theory wants to say something about their agents, thus decisions about what counts as “agent” and what not are likely to have important implications on the claims produced by that theory. 

Second, we can notice how a number of other interesting concepts (or, our understanding of them) are tied up with our understanding of individuality. For example, any notion of agency is based on a respective notion of “an agent” and agentic or goal-directed behavior is characterized with respect to the actions and goals of some agent (in contrast to the environment). More generally, any theory or functional account of agent behavior in a given situation or circumstance (e.g. behaviorism, rational actor models, bayesian epistemology or game theory) implies some ways of drawing agent-environment boundaries. 

Similarly, normative frameworks as we know them for examples from practical and political philosophy, too, tend to rely on certain notions of individuality. Do not cause harm. Is it better to have more, happy people (adding additional people who are happy) or more happy people (making existing people more happy)? If justice has to do with distribution (of wealth, opportunity, capability, etc.), what or who are we distributing things in between? If a juste state fosters feedoms, whose or what freedom do we have in mind?

But even if “individual agents” (whatever that is) are not the central subject of a theory in question, choices about where we draw boundaries around individuals may still affect how our theory cashes out (what predictions it makes) or at least how we interpret it. In evolutionary theory, different notions of individuality come into play. Richard Dawkins affected a field-internal move towards considering the gene itself as the relevant level of analysis when considering the game theory of evolution. At the same time, we should remember that the phenotype distribution of a population is exhibited at a different level, usually what we would classically consider an individual organism. Controversies in discussions about levels of selection highlight how it may even be that some selection pressure is being executed at the level of kin groups. (See e.g. Okasha 2006, Evolution and the Levels of Selection)

This should go some way to motivate deeper inquiry into the notion of individuality, albeit more is (and will later) be said about it.