If you were an engineer who was operating under a misconception about the laws of physics or the properties of different materials then your bridges would fall down. It wouldn’t matter whether you appealed to authenticity, excellence, creativity, inclusivity or anything else for that matter, the fact that your bridges fell down would be a problem. Your failure would be obvious and apparent to all. In the ancient world, you might have suffered a grisly fate and so I think it is no coincidence that columns and arches were understood pretty early in our history.
Medicine offers a more complex picture. On the one hand, a surgeon who kills his patients is going to run into trouble. However, if the alternative to surgery is certain death then even poor-quality, insanitary surgery might persist until something better comes along. In the case of illness, patients will often recover of their own accord. If this recovery coincides with a physician bleeding the patient or applying a patent medicine then these treatments gain credibility. Couple this with the complexity of the human body compared to the simplicity of a bridge and you can see why the advent of the scientific method was required before we could start to sort fact from fiction in medical research.
Education is also complex. It is hard to predict results at an individual level and so interventions need to be trialled across large numbers of students; a difficult and costly process. And just as patients will often recover of their own accord, students will often learn things on their own. The research question is therefore whether they learn relatively more this way or through some kind of instruction. We might also question whether a self-learning method will enable students to learn all of the things we think it is important for them to learn or only the stuff they find immediately appealing.
Regardless, I suspect most people would agree that children should learn to read. You might therefore think that the teaching of reading, at least, would be a bastion of evidence-based practice. Yet it is not. We know that a systematic, synthetic phonics (SSP) approach is the most effective method for teaching students to read and yet, in practice, phonics is often an incidental. As I have mentioned before, an Australian ‘best practice’ video treats phonics as a little old-fashioned and something of a last resort. You might find this astonishing.
It is not astonishing when you realise that SSP has only a relative advantage over other approaches. If it was the only way that children could learn to read then we would have a situation similar to the engineer and the bridge. Instead, there are lots of less efficient ways of teaching reading that still sort-of work. Many students will discover the alphabetic code for themselves, for instance. Directly teaching phonics does these students no harm and probably ensures that their knowledge is more systematic, whilst students who wouldn’t discover the principles for themselves will also learn. However, if you decide not to directly teach phonics then those students who fail to discover it may end-up labelled as having a learning difficulty. This then shifts the responsibility away from the teacher and his or her instruction. With these conditions and forces at play, a less effective strategy for teaching reading can survive and even thrive.
So mediocre, misconceived teaching persists because the harm it causes is relative and not immediately apparent.