Do I need to define these two? Yes, because they are not words that automatically come up in everyday conversation. Not even in technical conversations.
A qualitative approach to an argument deals with words, meanings, and experiences. Not so much opinions but defensible objective judgements based on best available information.
A quantitative approach to an argument deals with analysis, numbers and statistics. A scientific approach rooted in believable evidence that is reliable, repeatable, rational deduction.
In the aviation safety world, we use both. It’s my view that one is not subordinate to the other. However, the persuasiveness of one is greater than the other. At the end of the day, persuasiveness matters. If a key decision is to be predicated on an argument, then how it is constructed and presented matters a lot.
Many is the time when I have sat in a room listening to a person make a case in as elegant and enthusiastic a way that they can, but the results have been less than impressive. I’ve made the mistake myself. Coming prepared with a barrage load of sound evidence accompanied by a flaky presentation that misses the mark.
That is why the order needs to be thus. Establish a qualitative argument supported by quantitative information. Not the other way around.
In the field of aircraft system safety assessment this is vital. Probabilistic analysis is a powerful tool. Relating numbers to human experience is not so easy. So, detailed charts and logic diagrams sprinkled with numbers are unlikely to be enough on their own.
Stating an objective is met by handing over a pile of calculations is half the job. However impartial and truthful the numbers may be, arguments are not made until they are explained.
Many is the time when I have lifted a large report from my in-tray, studied it and concluded that there’s something missing in that gap between the QED and the statement of compliance.
Maybe this an element of safety regulatory psychology. It’s difficult to approve something if it becomes difficult to explain to others what’s been done. That evidence trail needs to be explainable. And easily explainable to a wide audience.
This doesn’t change with digitalisation. Replacing large piles of paper with large files of results puts the reader in the same position. Impenetrable evidence needs understandable explanation. Presenting a qualitative argument supported by quantitative information is a good way to go.
