Connections, Counterfactuals, and the 5Rs

I absolutely love people who make the Herculean effort necessary to view well-known things from a distinctly different point of view. One person making that effort is Chiara Marletto. I was introduced to her work a few years and reminded of it again this week by the wonderful interview with her in Quanta Magazine. (I was ecstatic to learn that she has published a book about her work – The Science of Can and Can’t: A Physicist’s Journey through the Land of Counterfactuals – which is already loaded up in my Audible.)

Chiara is working on what is called Constructor Theory. The interview provides a wonderful introduction to the work, starting here:

The goal of constructor theory is to rewrite the laws of physics in terms of general principles that take the form of counterfactuals — statements, that is, about what’s possible and what’s impossible.

Amanda Gefter

I’ve been taken with counterfactuals since I went down the rabbit hole of causality a few years ago, starting with The Book of Why (which I enjoyed so much I gave copies to several people) and then graduating to other writing on counterfactuals and causal inference. I was happy to see counterfactuals pop up again in the context of constructor theory and thinking about the connection between these two has my mind spinning with possibilities.

What does all this have to do with the 5Rs, you ask? As you may recall, the 5Rs are:

  1. Retain – make, own, and control a copy of the resource (e.g., download and keep your own copy)
  2. Revise – edit, adapt, and modify your copy of the resource (e.g., translate into another language)
  3. Remix – combine your original or revised copy of the resource with other existing material to create something new (e.g., make a mashup)
  4. Reuse – use your original, revised, or remixed copy of the resource publicly (e.g., on a website, in a presentation, in a class)
  5. Redistribute – share copies of your original, revised, or remixed copy of the resource with others (e.g., post a copy online or give one to a friend)

The connection came as I was reading the FAQ on It reads, in part:

An unexpected bonus of switching to counterfactuals is that in constructor theory we can talk objectively about additional entities (such as knowledge or information) that traditionally are considered anthropocentric or subjective. This is because for example information is defined implicitly by the concept of information medium – a system with a set of states on which all permutations and also the copy-like task are possible. Likewise, knowledge is information that is capable of remaining embodied in physical systems. Nothing in these definitions appeals to an observer or a knowing subject. In this sense, constructor theory is superior to the traditional conception of physics because it can handle these concepts on objective grounds, while the traditional conception cannot. (emphasis added)

These definitions of information and knowledge map nicely into the 5Rs. (Information into the original 4Rs and knowledge into Retain, the 5th R.) This connection was totally unexpected and caused me to clap my hands in delight. I love learning new things and making new connections.