Arguments from developmental order

One topic that I have thought about ever since writing my PhD thesis on concept learning is the role of developmental order in arguing for or against a given psychological (or philosophical, for that matter) claim. In this blog post, I will explain the problem of developmental order and I will introduce the two main positions one can adopt in response. I don’t have a clear position on the matter, but I hope to provoke some thoughts and a discussion about the issue in what follows.

Consider any given mental capacity M that has a developmental trajectory: the ways in which humans use M changes over their lifespan. At a given point in early childhood, the consensus is that children use process P1 to perform that specific task. 

Over the course of development, P1 gets replaced, or supported by, further processes P2, P3, and P4. The typical adult will use a given set of mental capacities, that might contain P3 and P4, or evolved forms of P1 and P4, just P4, or any given combination of these processes.

So, for the cognitive scientist, the question is: Which mental process is fundamental for understanding human cognition with regard to M? As an example domain, consider the structure of human concepts – so, M stands for conceptual thinking. I had discussed the issue with Edouard Machery during his 2012 visit to Edinburgh, where we held a Q&A on Machery’s book “Doing without concepts” (Machery 2009). 

One of the main claims Machery makes in his book is the Heterogeneity Hypothesis: there are multiple kinds of concepts – at least, prototypes, exemplars, and theories – independently at work in human cognition, and there are no good reasons to privilege any of them more than the others (i.e., there are no reasons to regard any one of them as more fundamental than the others).

There are two directions to argue in here: One could, first, argue that the developmentally early process P1 is indicative of how the mind works with regard to M. Theoretical accounts of M should, on that view, keep the initial state and the first processes for M at the centre of their models. 

Later developments do not replace these initial processes, one might say, because they might only be more elaborate versions of P1, or that P1 would be sufficient to perform the key role that P4 has in adult cognition. Without this starting point, the whole development of M might never have gotten off the ground, or it might have evolved into a very different mental capacity.

In our example, one might say: Developmental research can show us that one type of concept is the first one used in infancy. The initial stock of concepts an infant forms takes the form of prototypes, or exemplars, or maybe theories. All other kinds of concepts are later developments and thus cannot be part of the foundations of conceptual thinking.

One could, second, also argue that the developmentally late process P4 is fundamental for explaining M – P4 is the correct anchor for a theory of M. After all, it is the mature form of the process. It might have many advantages, such as a better integration with other mental processes; P1 could be a very simple form of associative thought, for instance, and P4 could be a reasoning heuristic that is integrated with a large store of background knowledge. 

Also, P4 appears to have the “normative force” on its side: It appears that this is how M is done right, ie, it’s the best that human cognition has come up with to solve the given problem, or perform the given task, and it should therefore be considered fundamental or central.

To return to the example of concepts: One can argue that developmental priority by itself wouldn’t be a good reason to privilege one type of concept over others, as the cognitive power that comes from having the diverse kinds of concepts at one’s disposal is a stronger reason for denying any one of them such priority.

In my own past and current research, I have been drawn to both versions of the argument, and I think there is an issue of methodological interest connected to it. Indeed, similar issues have been in the spotlight of developmental research for quite some time; one example is the question of the (dis)continuity in conceptual change (cf. Carey 2009 for a proponent of the discontinuity view, ie, that many concepts are radically different in meaning before and after an important step in conceptual development). 

Another related issue is whether giving an explanation of the developmental trajectory of a cognitive process is a special (or especially important) virtue of a theory. These are important questions at the intersection of psychology, philosophy of science, and philosophy of mind in general that could feed into a “philosophy of development” more generally. I would be very interested in discussing the issues I introduced above further, and to hear other examples and considerations.

References

Carey, S. (2009). The origin of concepts. Oxford University Press.

Machery, E. (2009). Doing without Concepts. Oxford University Press.