The summer before I started university, I was given a reading list. On this list was Richard Dawkins’ “The Blind Watchmaker”. It had a major impact on me. Prior to this point, I had implicitly accepted a concept known as ‘irreducible complexity’ which can be encapsulated by the question: What use is half an eye? Basically, proponents of irreducible complexity doubt whether something as complex as an eye could evolve through a series of infinitesimal steps, each of which confers a small but significant advantage on an organism in the way that Darwinian evolution suggests. Instead, these features must emerge fully-formed. In The Blind Watchmaker, Dawkin’s patiently describes each tiny step in the evolution of the eye; how a patch of light-sensitive cells confers an advantage over organisms which cannot sense light, how having these cells in a depression on the skin gives some sense of the direction of the light and how this is an advantage over just having the cells on the surface and so on. Dawkin’s proceeds to build to a whole eye in such steps. He even notes that eyes have evolved independently in a range of different organisms.Most of those who accept irreducible complexity are motivated by religion. It is a key argument put forward for pseudoscientific theories of intelligent design which reject evolution in favour of some form of creator. I had a more idiosyncratic view, holding that evolution did occur but must have proceeded via great bursts of mutations, probably caused by radiation from space. Whatever I had thought, Dawkins changed my mind.
However, I think that we can draws some useful parallels here for education. Consider an intervention, teaching method or innovative approach. Must it be adopted wholesale? Will implementing parts of it give some of the claimed advantages? Of course, it is entirely possible that there are interventions that are greater than the sum of their parts but if this is the case;
1. Why is this so? What mechanism causes it to work only if all components are present?
2. Is it really going to be possible to implement this intervention at scale if it’s only going to work if everyone adopts it faithfully?
The problem with accepting the irreducible complexity of a particular approach is that when and if it fails to produce results then proponents of the intervention can always claim that it wasn’t done properly. This can even approach the ‘no true Scotsman’ fallacy whereby the fact that it didn’t work proves it wasn’t implemented properly. In scientific terms, we have an unfalsifiable claim.
How can we be sure something is not irreducibly complex? If we examine Engelmann’s Direct Instruction then the different components of it should each confer some advantage over not having them in place; explicit instruction on concepts and procedures, immediate corrective feedback, practice, a systematic approach (over a serendipitous one) and scripted lessons. I think the evidence supports the first four of these, with some caveats around how and when feedback should be immediate. I am not so sure about the scripting of lessons because I know of few other examples where this is used. On balance, I am happy to conclude that such an approach does not display irreducible complexity and is therefore likely to work at scale.
Try applying this test to a different intervention.