Why Process Safety Professionals Disagree on Risk, Hazard and Safety Definitions

The Myth of Absolute Safety

Absolute safety and security are a fantasy, as has been known for quite some time now by anyone who gave the matter any serious thought.

There is no safety for honest men, but by believing all possible evil of evil men, and by acting with promptitude, decision, and steadiness on that belief.”

Edmund Burke (1791)

Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure, or nothing.”

Helen Keller, The Open Door (1957)

So, there is only relative safety, but both “safety” and many of the key terms underpinning the approach to safety followed in chemical engineering are vague and their meanings contested:

Many of the central terms in safety research are in need of clarification, such as “risk”…“precaution”…“safety factor”…“inherent safety”…“substitution” and “(safety) barrier”.

Sven Ove Hansson, Safety is an inherently inconsistent concept (2012)

Risk and Hazard: Too Many Definitions, Too Little Agreement

I define a few of these terms in my dictionary, where I noted that “Risk” had 40 different definitions according to ISO alone. My own dictionary definition of risk goes like this: “… most commonly held to be the probability of an adverse effect or hazard occurring, multiplied by the severity of outcome if it occurs. It is however a highly contested term”

I also felt compelled to discuss the term as follows:

“At its broadest, it is used to mean the effect of uncertainty, and is most commonly held to mean “the probability of an adverse effect or hazard occurring”.

However, it is also used to mean the possibility of an effect (not quantified as with a probability), the severity of the effect, or the product of the probability and the severity. I would differentiate risk from hazard in that where a hazard is a potential harm, risk is the likelihood of it happening, but, whilst this is a commonly held view, it clashes with other formal definitions of both hazard and risk.

In fact, virtually every part of my “most commonly held” definition is disputed: whether it involves possibility or probability of an effect, whether it only refers to adverse effects, whether the effect constitutes a hazard are all up for grabs – even in formal definitions from reputable international standards organisations…

…Most significantly, the ISO definitions cannot agree about what a risk is; what or who it affects; whether it is always adverse; whether it is the probability of something, the outcome of something, the product of these two, the sum of them, both together or each separately; or simply the effect of uncertainty…my discussions about risk with fellow practitioners have shown me that even the most highly qualified risk specialists do not agree with each other about the definition of the subject of their specialism…”

Why Safety Professionals Argue (Even in Public)

Which brings me to the thing I really wanted to discuss. Why are safety specialists so often to be found having very public, often ill-tempered arguments about the basics of their specialisation on LinkedIn? Is it something to do with their apparently not having agreed a common language?

My working hypothesis is that a number of factors are working together to stop them from doing so. It seems implausible that the profession simply just hasn’t got around to defining its most fundamental terms yet. Most scholars think that “safety engineering” started with the Industrial Revolution, which was a while back now. Something is stopping them from agreeing on definitions.

The Fragmented Backgrounds Behind the Safety Role

My primary suspect is that it is something to do with the fact that “safety specialists” come from a wide range of backgrounds. There are graduate engineers, scientists, psychologists, an assortment of management/business studies types, even social workers. There are also quite a lot of non-graduates, often time-served, who may have moved into safety via NEBOSH-type qualifications.

This means that “safety specialists” are not one thing at all. They have different levels of education, ranging from around A level to PhD. Their disciplines have different rules for determining the truth of an argument, and different degrees of mathematical and linguistic skill are required of practitioners. Some of them love a bit of beard-stroking philosophising, some of them want to make the world a nicer, fairer place, but many just want to get the boxes ticked on the form so that the job can go ahead.

Why There’s Still No Agreed Safety Lexicon

So, it would appear that the reason why there is no lexicon of “safety” is that there is no such thing as a safety specialist. Each discipline within the field (especially the more numerate ones) could probably agree a lexicon if left to themselves, but the existence of the other – seemingly equivalent – disciplines muddies the waters.

What This Means for Safety Practice and Public Perception

The least numerate disciplines generate junk research which makes it possible to cite “scientific references” for wrong-headed views. Some from the more numerate disciplines might then latch on to this, both because verbal reasoning is not their strength, and because they have a personal preference for whatever it is that the humanities / business / management studies types are peddling.

I can understand the basic feeling of resentment that many working in safety have. All too often, no-one likes them, or takes them seriously. They are widely seen as at best a necessary evil, as the annoying little externally imposed jobsworth with a clipboard, getting in the way of the job getting done. It must be awful being that person, but don’t squabble amongst yourselves on LinkedIn about stuff no-one else cares about. It’s just playing to the stereotype.

FAQs: Why Safety Professionals Disagree on Definitions

Why do safety professionals disagree on the definition of risk?
Because “risk” has over 40 different definitions in international standards, including ISO. Professionals from different disciplines (engineering, management, psychology, etc.) use different frameworks, making consensus difficult—even within the same organisation.

Is there a universal definition of safety or risk?
No. Both “safety” and “risk” are contested terms. Some define risk as probability × severity; others as the possibility of harm; others still as the “effect of uncertainty.” Even among experts, definitions vary widely.

What is the difference between risk and hazard?
A commonly accepted distinction is that a hazard is a potential source of harm, while risk is the likelihood or probability of that harm occurring. However, even this basic separation is debated in formal safety literature and standards.

Why is there no agreed lexicon for safety terminology?
Because “safety professionals” come from a wide range of educational and disciplinary backgrounds. Each group—engineers, psychologists, compliance officers—brings its own methods and definitions, making a shared safety language difficult to establish.

What are some of the most contested terms in safety science?
Terms like risk, precaution, inherent safety, barrier, safety factor, and substitution are commonly used but often mean different things depending on the context or the discipline using them.

Why do safety discussions often become public arguments online?
Disagreements over fundamental terms and professional identities often surface on platforms like LinkedIn. Without a shared language, even highly qualified experts clash over what should be basic principles.

Does this disagreement undermine the safety profession?
It can. Public disputes over terminology can reinforce negative stereotypes—that safety professionals are obstructive or inconsistent. Clearer internal alignment would strengthen the profession's credibility.