I took the liberty to insert quite some of my own thoughts and remarks in the ‘reviews’ of the three books before, so I’ll keep this short for now.
After having spent ample time with Heinrich’s work, I’d like to credit him for the groundbreaking work he has done. Sure, I have read none of his contemporaries (if there are any) but in some things he was ahead of his time, just as in some other things his writings exactly reflect the spirit of the times. But in that respect he no doubt is like any other author. And like any piece of science, it should be taken, tested, refined and rejected, something we have seen that has been done. So even if we strip a lot of out-dated stuff from his work, he has left us some worthwhile principles (e.g. the Common Cause Hypothesis) and at least two brilliant metaphors (the dominos and the pyramid) that are easy to communicate even to safety novices.
What disappoints me with Heinrich’s work is that he in a way wasn’t consequent. It’s as if he hasn’t thought through things far enough. Why did he get stuck in his focus on direct causes? Why did he have this focus on unsafe acts? He mentions the concept of underlying causes, and he discusses at length other measures than human-directed ones, yet doesn’t make this his key message. Was it his insurance background, or maybe a deeply rooted belief and misunderstanding of psychological factors? Or did Heinrich work on the premises that if the environment was as it should, the last thing remaining was focus for the human acts? He doesn’t say this explicitly and anyway it wouldn’t entirely be so. Whatever it is, I don’t know the answer to these questions. But luckily we have the benefit of hindsight and 80 years of additional safety science to pick the valuable bits out of his work and do a god job.
As for Manuele… in The Netherlands there’s a saying: “De beste stuurlui staan aan wal”, meaning that those who think they know best and have most critical remarks don’t actually participate in solving the problem. That pretty much sums up much of my impression of Manuele’s booklet. He makes the job for himself very easy by attacking mostly things that are easy to ‘falsify’ (notably the numbers) but not coming with any sensible suggestions for improvement. Most of Manuele’s chapters leave me with a very unfinished feeling: he disproves something, but not quite: he often doesn’t finish the job and leaves arguments hanging in the air. Which also applies to critical remarks he makes underway, for example addressed to the entire Behaviour Based Safety movement. He just doesn’t work out his statement into something concrete.
And then the question why Manuele chooses to neglect the revised 1980 version of Heinrich’s book as well as all the updates of Heinrich’s models by people like Bird (who improved both the dominos and the pyramid and also the ‘hidden cost’ principle)… Highly questionable if you ask me.
At any rate - one of the most important skills of safety professionals is to be critical and question things all the time. Including their own scientific (or something ideological) basis. So for me this was a worthwhile exercise.
Now it’s your turn!
(Editor's note: the Heinrich articles were written in autumn 2011 and have not been revised since)