The idea of a different mode of explanation is a difficult meta level concept to grasp. I find the historical context of evolution helpful here: An evolutionary mode of explanation is quite different than an intelligently designed solution. To understand evolution is to embrace this different mode of explanation.

Deutsch argues that great advances and discoveries are enabled by and contingent on the discovery of new modes of explanation. Constructor theory is a great example of how Deutsch practices what he preaches. The difficulty and importance of the creativity problem in AI suggests that a new mode of explanation is needed here, as well.

Deutsch highlighted this aspect as the central point of disagreement with Wolfram:

Wolfram seems to share a fundamental mistake with the majority of mathematicians and computer scientists, namely the belief that “simplicity” can be defined independently of the laws of physics. This tempts one to see computer programs “underlying” physical processes instead of vice-versa, and so to misconstrue the relationship between computation and physics…

Hence my first impression is that the book’s central thesis is false: I do not think that the sciences (and beyond) will be revolutionised by reinterpreting nature in terms of simple computational rules rather than simple equations. It’s an interesting perspective, and may become valuable. But I see no revolutionary change in scientific theory or methodology in prospect here — no whole new kind of science.