The reason for these medical sounding terms is that they follow similar principals - you need to understand the underlying cause of something to be able to put it right. Building Pathology is a relatively new concept in terms of Building Surveying, and it is now a separate competency within the RICS Assessment of Professional Competence. To qualify as a Chartered Surveyor, you need to be able to prove to a panel of experts that you can - and have - successfully identified the underlying cause of existing defects.
The reason this is important? It is very easy to fix the symptom of a problem without removing its cause - a bit like giving painkillers for a bad back. While the pain killers help for a short time, what you need is to have the problem with your back addressed so that you will be fine and not need any pain killers.
For example: just because paint is blistering on your wall just above the skirting board doesn’t necessarily mean that it’s ‘rising damp’. If you inject a waterproof chemical and re-plaster it may seem like you’ve solved the problem.
And maybe you have - for a while.
But the issue may be water coming from elsewhere - and it may even be historic water damage. So you may have actually paid twice to fix something that was already resolved! Or you might have put nice fresh plaster back onto a wall which will remain damp - and this will take a few years to show back through.