What Does it Mean to Be an Expert?
As it turns out, capturing what it means to be an expert is quite challenging. Here, I offer a brief survey of the philosophical literature concerned with defining the concept of “expert”.
We go to the doctor when we’re sick, call the plumber to fix faulty pipes and rely on scientific experts to advise governments on complex public issues. Experts play central roles in our lives. But what is expertise, and when can we say someone is an expert? Some philosophers are occupied with precisely these questions. Here, I explore the academic (i.e., social-epistemological) debates on “expertise” and provide a succinct overview of key discussions on the topic for a broader audience. As we shall see, capturing what it means to be an expert is difficult, but turning to the standards we apply to judge whether someone is an expert may help build a shared understanding.1
According to Malcolm Gladwell’s book Outliers, one needs to practice for at least 10,000 hours to gain expertise in a particular area. But how plausible is this? And why 10,000 hours exactly? What happens to a person when he or she goes from 9,999 hours of practice to 10,000?2 In short, what does it mean to be an expert?
The etymology of “expert” teaches us that this word stems from the Latin experīrī, which means to try or experience. So, Gladwell’s focus on practice seems to be on the right track.
Types of Expertise
Lionel Messi is an expert at keeping the ball at his feet, a dendrologist is an expert on trees, Janine Jansen is an expert violinist and some fighter pilots (“aces”) are experts in air combat – the aces in the Luftwaffe were referred to as Experten. In short, there are many different types of expertise out there.
What especially Messi and Jansen have in common is that their expertise concerns mostly a “know-how”, a particular skill set that others do not possess.
Identifying whether someone has these particular skills seems relatively easy for laypeople. Sure, discussions remain on whether Cristiano Ronaldo or Messi is better in certain activities and whether the violinist is performing “well”, but it seems that we all can verify, most of the time, whether a plumber is “good” by observing that the faulty plumbing is fixed even though we don’t possess the same skills (or technê). As Aristotle said,
[…] the arts whose products can be understood even by those who do not possess any skill in the art. A house, for instance, is something which can be understood by others besides the builder: indeed the user of a house […] will judge it even better than he does. In the same way […] the diner, not the cook, will be the best judge of a feast.
However, can we laypeople also identify an expert plumber? Is that different from a “good plumber”?
More interesting for philosophers is the focus on cognitive experts, who possess “know-that”. This is also called propositional knowledge – e.g., an entomologist knows that ants can be found virtually everywhere on Earth except in Antarctica and some other island nations.3 I will be focusing on cognitive expertise here.
Yet, the distinction between “know-how” and “know-that” is not clear-cut. A plumber doesn’t merely possess relevant skills but also theoretical knowledge (or epistêmê). Another example is a brain surgeon, who must not only know how the brain functions but must also possess the relevant skills to operate successfully.
Identifying Cognitive Experts
In general, it is tricky for laypeople to identify genuine cognitive experts – especially if experts are those who are right (see below). How can I verify that the Pinus longaeva doesn’t exhibit senescence as measured in the xylem and phloem, which are important parameters for the cambium function?4
Now, there might be ways to discern “real” from “fake” experts by looking, for instance, at whether the predictions of experts have come true (i.e., evaluating their track record), but not all scientific disciplines are characterised by making predictions. Also, the credentials of a putative expert might be a good heuristic, such as a PhD. Yet, someone with a PhD could still say something of which she has no knowledge (e.g., discussing topics outside her field), or she can be (accidentally or maliciously) wrong. Discussions about “fake experts” are especially prevalent in today’s political climate. But these discussions focus more on how laypeople can identify experts or who we should trust and not on what is expertise proper (see this academic paper for more about these discussions).
Objective or Subjective Abilities?
The main discussions in the literature on cognitive expertise relate to objective and subjective expert abilities. That is, objectivists would say that someone is an expert independent of others saying that she is, whereas subjectivists would say that someone is an expert only if a relevant group says that she is. Below, I dive into some of the main elements of these approaches.
Domain-Related Expertise
A point on which little disagreement exists, though, is that someone is an expert in a particular domain. Nevertheless, with the hyper-specialisation and interdisciplinary works of science, becoming, for instance, an expert in physics tout court seems impossible, considering the various sub-fields, such as cosmology and nuclear physics.
In public administration, the distinction between “tame” and “wicked” problems is often made to mark the nature of domain-related questions. Tame problems are well-defined problems with clear goals and available knowledge, like installing traffic lights at a T-intersection. Cognitive experts, however, often deal with wicked problems which involve great uncertainty and value judgments, such as scientists advising governments about whether and which schools should be closed during the COVID-19 pandemic.
Experts Are Right
Arguably, the most influential objectivist account comes from Goldman (2001): ‘people who have (or claim to have) a superior quantity or level of knowledge in some domain and an ability to generate new knowledge in answer to questions within the domain’ (p. 91).
According to this definition, experts know facts relevant to their field – i.e., they are right or possess true beliefs – more so than non-experts, and they are able to generate new knowledge in a particular domain.
However, possessing true beliefs – i.e., knowing facts – is not sufficient for being an expert. For instance, I can just memorise many facts. Take Nigel Richard, for instance, who allegedly became the French Scrabble champion by memorising the entire French dictionary without being able to speak French. This is impressive, but is he an expert French speaker or an expert in the French language?5
In addition, a novice might have only a few beliefs related to a particular domain, but these may all be true. An expert, on the other hand, may possess fewer true beliefs than a novice because the expert is occupied with many unresolved issues within that domain.
Furthermore, Goldman introduces a threshold of possessing true beliefs (“superior quantity”), but this gives rise to tensions when we consider experts in the past: For example, Ignaz Semmelweis, who can be considered an expert physician, advocated for handwashing among obstetricians, thereby reducing the transmission of puerperal fever, cutting mortality rates by over 90%. However, his justification for this belief was false (see Watson, 2018). Still, it seems fair to call him an expert.
Facts, or what we take to be facts, can change when science progresses. Therefore, it could be that those we regard as experts today – because we think they possess more “true beliefs” than others – may very well no longer be experts in just a few years.6
Concerning the condition that an expert should be able to generate new knowledge, David Coady (2012) argues convincingly that someone who holds true beliefs in a domain but loses their ability to generate new knowledge in that domain due to cognitive impairment can still be considered an expert.
Similar to Goldman’s approach, I came across a quote online attributed to the physicist Niels Bohr:
An expert is a man who has made all the mistakes that can be made in a very narrow field.
First, the use of “man” is clearly outdated. More importantly, how can we know when someone has made all the possible mistakes in a given field? Does this also mean that the expert will not repeat those same (and, therefore, all) mistakes? This seems too demanding and unlikely to be used as a condition for being an expert.
However, if experts do not need to be right, then could we also speak of experts in pseudo-scientific fields, such as astrology?
Being and Becoming an Expert
Objectivist accounts do not necessarily have to reject social factors, but they must separate someone’s being and becoming an expert as well as their display of expertise.
When a doctor goes to a town where no one knows her, she is an expert due to her abilities, independent of others thinking she is a doctor (Goldman, 2018). Indeed, the doctor is an expert independent of her reputation. However, as with other professions with protected titles, her being a doctor is dependent on social factors (e.g., board certification).
Doctor or Expert?
Imagine a doctor, Lisa, who on the day of official retirement, still possesses more true beliefs than most others in the health domain (perhaps even more true beliefs if she gained new knowledge right after officially retiring) and is still capable of generating new knowledge. An objectivist would separate her profession (being a doctor) from her expertise in medicine, which remains even if she is no longer officially recognised as a doctor and, thus, prohibited from displaying “doctor abilities”. Yet, once a retired doctor, when does Lisa stop being an expert?
Concerning becoming an expert, one does not often become an expert independently of others. For instance, you must learn from other experts. Yet, sometimes one could learn autodidactically through reading books (or reliable Substack newsletters) or watching videos online.
Yet, again, once an expert, one’s abilities exist independently of any display of expert abilities. Indeed, displaying expert abilities is insufficient for being an expert. Think of the following case:
Expert coder?
Barry impresses a company during a job interview by displaying exceptional coding skills, subsequently getting hired and outperforming colleagues. Yet, Barry has been paying someone to write his codes and to give an explanation that Barry just repeats when asked to elaborate.
Expert Reputation
Subjectivists would say that someone is an expert merely because others say he or she is. One particular approach is called the “service account”: someone is an expert when this person competently offers a service to people. This pertains to a particular role that someone has. An expert private equity investor, for instance, might not always be right, but he still generates a lot of money for his clients.
It also points to a more flexible understanding of expertise: someone acts as an expert within that role. When the expert investor retires, he could say that he worked as an expert investor for his clients. A colleague of mine once told me that her father “was a doctor” and quickly added that “he is not dead, he just retired”. Perhaps it was best for her to say that her father worked as a doctor (or as an expert in human health).
Moreover, these views often emphasise that part of being an expert includes acting responsibly. This can mean that experts must act according to good ethical conduct, be liable to sanctions, own up to mistakes, etc. Take doctor Gregory House, he always seems to be right, but the way he gets to the truth and how he treats his patients is often far from responsible…
Expert responsibility might also include the willingness to explain their knowledge. In this regard, Semmelweis appears to have fallen short: ‘The calls for proof by [Semmelweis’] colleagues were interpreted as a personal insult. He responded by being rude to them and this made the situation worse’ (Best & Neuhauser, 2004, p. 234).
Yet, expert explanations might not always be possible due to time constraints, and the level of explanation resulting in understanding differs per audience.
On the whole, the main problem with these reputational views is that they can quickly turn into relativism: this group’s expert is another group’s fraud.
Ubiquitous and Lay Expertise
A final type of expertise provokes thoughts on a democratised understanding of who is an expert. Gaining more popularity in academic debates is the oxymoronic term “lay expertise”. This can refer to the local knowledge someone, who isn’t a credentialed scientist, possesses about his or her own situation.7
A patient knows more than the doctor what the pain feels like and an expert witness to a crime knows a lot about the crime, certainly more than most others in the courtroom (with, perhaps, the exception of the perpetrator and victim). Others have said that these people are not experts but “authorities” regarding their situation.
Sociologist Harry Collins has spoken of “ubiquitous expertise”, denoting how expertise is not only esoteric (e.g., experts in nuclear physics) but also more common, such as expert English speakers. According to Collins, experts are “socialised” in a group and have to pass a sort of Turing test to be considered an expert in that field – native English speakers, for instance, could tell me whether I am an “expert English speaker”.
Still, some worry about deflating the term “expert” and giving room to uninformed opinion when including virtually everyone, or a large group of people, in being an expert or possessing expertise.
Conclusion
It seems to me that the tendency to focus on necessary and sufficient conditions in understanding our world – and in this case, the concepts of “expert” and “expertise” – often limits our ability to draw from a range of viable perspectives and to expand our heuristics. How many hours of practice are enough? How many “facts” should one know? How many people must agree for someone to be an expert? All these “tipping points” seem arbitrary.
The discussions above represent only a small fraction of the academic literature. There are many promising approaches out there. However, with the rise of artificial intelligence and especially large language models, new questions arise about how we define and refer to experts and expertise.
In my view, turning to the standards we should apply to judge whether someone is an expert is promising in building a shared understanding of what it means to be an expert.
Lucas Dijker
For an excellent and more comprehensive overview of the philosophical debates in an academic paper, see Baghramian & Croce (2024).
Psychologist K. Anders Ericsson’s work has been cited as the basis for a simplified, popularised view that achieving a sufficient number of practice hours in a domain guarantees expertise. However, Ericsson has rejected this attribution. Note also that these studies focus on elite sports athletes, not on cognitive experts.
Trying to be epistemically responsible, I want to add that I am not an entomologist, and I am not 100% sure if this is correct… But the example is for illustrative purposes anyway.
That is, according to this study the Great Basin bristlecone pine – a tree found, for instance, in parts of California – does not exhibit significant signs of ageing (some are reported to be older than 4,000 years).
Richards recently also won the Spanish World Scrabble Championship without speaking Spanish… He must be an expert in memorisation. But how many “facts” (or words, in this case) must one memorise to be an expert in memorising?
A potential way out of this is to consider someone an expert who possesses more true beliefs than others at a given time t.
There are several examples in the academic literature about lay expertise. Brian Wynne’s case on Cumbrian sheep farmers is widely taken to be an example of this type of expertise – also check out this post about this case.