Traditionally, cognitive science has held the view that the human mind works through, or is at least best explained by, mental representations and computations (e.g., Chomsky 1965/2015; Fodor 1975; Marr 1982; Newell 1980). Radical enactivist accounts of cognition challenge this paradigm. According to them, the most basic forms of cognition do not to involve mental representations or mental content; representations (and content) exist only in minds that have access to linguistic and sociocultural truth-telling practices (Hutto and Myin 2013, 2017).
As presented by Hutto and Myin, radical enactivism is a general approach to the philosophy of cognition. It is partly from this generality that it gets much of its force and appeal. However, a general theory of cognition ultimately needs to be tested on particular cognitive phenomena. In my paper, I set out to do just that with regard to arithmetical cognition. I am not a radical enactivist, but neither am I antagonistic to the approach. My aim is to provide a dispassionate analysis based on the progress that has been made in the empirical study and philosophy of numerical cognition.
Arithmetical cognition is especially suited to test radical enactivism (Zahidi 2021). This is not because arithmetic itself suggests the existence of non-linguistic representations. In fact, since Dedekind and Peano presented an axiomatization for arithmetic, it became clear that the entire arithmetic of natural numbers can be presented in a very simple language with only a handful of rules (i.e., the axioms) (Dedekind 1888; Peano 1889).
It is not arithmetic as a mathematical theory that presents challenges for radical enactivism; it is rather the development of arithmetic. This development happens on two levels. First, at the level of individuals, we have the ontogenetic development of arithmetical cognition. Second, at the level of populations and cultures, we have the phylogenetic and cultural-historical development of arithmetic. In my paper I focus on the ontogenetic level, because it is at that level that radical enactivism faces its most serious challenge.
It is commonly accepted that, in learning arithmetical knowledge and skills, children apply their innate, evolutionarily-acquired proto-arithmetical abilities (Pantsar 2014, 2019). These abilities – sometimes also called “quantical” (Núñez 2017) – are already present in human infants, and we share them with many non-human animals.
According to the most common view, there are two main proto-arithmetical abilities (Knops 2020). The first is subitizing: the ability to determine the amount of objects in our field of vision without counting. Subitizing enables detecting exact quantities, but it stops working after three or four objects. For larger collections, there is an estimating ability. This ability is not limited to small quantities, but it gets increasingly inaccurate as the size of the observed collection increases.
For the present topic, the literature on subitizing and estimating presents interesting questions. Following the work of Elizabeth Spelke (2000) and Susan Carey (2009), it is commonplace to associate each ability with a special core cognitive system (Hyde 2011). Subitizing is associated with the object tracking system (OTS), which allows for the parallel observation of objects in the subitizing range, up to three or four. Estimating is associated with the approximate number system (ANS), which is thought to be a numerosity-specific system.
The problem for the radical enactivist is that, under most interpretations, both the OTS and ANS are based on non-linguistic representations. The OTS is based on the observed objects occupying mental object files, one file for one object (Beck 2017; Carey 2009). For example, when I see three apples, three object files are occupied, and we can understand this as a representation of the number of the apples.
The ANS, on the other hand, is usually interpreted as representing quantities on a mental number line (Dehaene 2011). This line is likely to be logarithmic, given that the estimating ability becomes less accurate as the quantities become larger. Studies on anumerical cultures in the Amazon provide further evidence of this; members of those cultures tend to place quantities on a (physical) number line in a logarithmic manner (Dehaene et al. 2008; but see Núñez 2011).
Therefore, we have good empirical evidence in support of the idea that proto-arithmetical abilities are to be interpreted in terms of non-linguistic representations. Now the question is: can radical enactivism provide an alternative explanation for proto-arithmetical abilities without evoking representations?
This proves to be difficult, because it requires answering what is perhaps the most fundamental question in the field: namely, what exactly is a mental representation? Should visual memories, for example, be considered representations? For the radical enactivist they should not, but little evidence or argumentation has been provided to support this denial. In the present context, we must ask: could the OTS and the ANS work without using representations? Radical enactivism says so, but there is little solid evidence in support of this view.
Nonetheless, it should also be noted that the object files and the mental number line as explanations of the functioning of the OTS and the ANS, respectively, are currently nothing more than theoretical postulations : neither object files nor a mental number line have been located in the brain at the neuronal level, although fMRI studies give us good clues on where to look (Nieder 2016).
To be sure, some monkey studies have detected the existence of number neurons: i.e., specific groups of neurons whose firing is connected to observing a particular (small) quantity of objects (Nieder 2016), and one could infer that such number neurons count as representations of quantities in the brain. But this inference is exactly the kind of inference that radical enactivists have warned us against. Radical enactivists agree that there is non-linguistic processing of information in the brain, but they deny that in such cases there is content, i.e., representations. In the words of Hutto and Myin, brains process non-linguistic information-as-covariance, but not information-as-content (Hutto and Myin 2013:67).
In conclusion, where do we stand? Is there a way forward in the debate on representations? I believe there is, but it would be spurious to claim that philosophers can find it on their own. Instead, we will need a better empirical understanding of the neuronal activity associated with the functioning of the OTS and the ANS. At the same time, it would also be misguided to expect empirical data alone to resolve the issue. We will not find groups of neurons that are unassailably non-linguistic representations, and philosophers will need to continue working with empirical researchers in an effort to gain more knowledge about the proto-arithmetical abilities.
Read the full article at https://journals.publishing.umich.edu/ergo/article/id/3120/.
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About the author
Markus Pantsar is a guest professor at the RWTH University in Aachen. He has the title of docent at University of Helsinki. Pantsar’s main research fields are philosophy of mathematics and artificial intelligence. His upcoming book “Numerical Cognition and the Epistemology of Arithmetic” (Cambridge University Press) will present a detailed, empirically-informed philosophical account of arithmetical knowledge.