Constructor Theory: David Deutsch et al.'s new (information) theory of everything

In the current issue (24 May 2014) of New Scientist is another opinion piece from David Deutsch and Chiara Marietto on their 'Constructor Theory'.

WHEN we consider some of the most striking phenomena permitted by the laws of physics – from human reasoning to computer technologies and the replication of genes – we find that information plays a central role. But, on the face of it, information is profoundly different from the basic entities that physical sciences use to describe reality. Neither quantum mechanics nor general relativity, the most fundamental theories in physics, provide a meaning for information or even a way of measuring it. And it has a "counterfactual" character: a message cannot carry information unless a different message is also possible.

Statements about information were therefore long regarded in physics as second-class, non-fundamental approximations. Information itself was considered an a priori abstraction, like Euclid's perfect triangles and circles, whose physical instantiations are inevitably approximate. [...]

[Constructor theory] makes knowledge creators, such as people, central to fundamental physics for the first time since Copernicus debunked the geocentric model of the solar system.

Reconstructing physics: The universe is information

A good place to find more about constructor theory is a video interview (with transcript) that Deutsch did a couple of years back: here CONSTRUCTOR THEORY. A Conversation with David Deutsch

It's 47 minutes long and covers a lot ground, both introducing the theory and talking extensively about why he's doing it and more general thoughts on science and philosophy. For my own present concerns, there's a couple things I'll pick out.

Firtly, his speculation that cybernetics was a precursor of constructor theory:

I'm not very familiar with the very popular idea of cybernetics that came about a few decades ago, but I wouldn't be surprised if those ideas that proved at the time not to lead anywhere were actually an early avatar of constructor theory. If so, we'll only be able to see that with hindsight, because some of the ideas of constructor theory are really impossible to have until you have a conceptual framework that is post quantum theory of computation, i.e., after the theory of computation has been explicitly incorporated into physics, not just philosophically. That's what the quantum theory of computation did.

Secondly, the scope he is claiming for the significance of the theory. He is claiming that the theory delivers 'optimism', with the specific claim that it shows that "all problems and all evils are caused by lack of knowledge, and the converse of that is that all evils are soluble given the right knowledge".

[T]here is one big thing that I'm pretty sure the constructor theoretic way of looking at physics has to offer our worldview in terms of everyday life: and that is optimism. Optimism in my terminology doesn't mean expecting that things will turn out well all the time. It's this very specific thing that I think captures the historical, philosophical trend of what optimism has meant if you remove the nonsense. Namely, the optimistic view is not that problems will not occur, but that all problems and all evils are caused by lack of knowledge, and the converse of that is that all evils are soluble given the right knowledge.