How do we know if what we know is true?

John Goldie is a retired GP and medical educator

As GPs, our professional journey is defined by continuous learning, not only gaining knowledge and skills but also in shaping our attitudes and beliefs.

Professional practice requires the integrated use of several types of knowledge. Eraut conceptualizes the knowledge base of a profession as including three main types:^1,2

1. Codified Knowledge: This is formal, propositional knowledge, typically found in books and journals.
2. Cultural Knowledge: Acquired informally through participation in professional practices, this knowledge is often unwritten and operates beneath conscious awareness, yet it significantly influences behaviour.
3. Personal Knowledge: This encompasses what individuals bring to situations, including codified knowledge ready for use, knowledge gained through enculturation, experience, social interaction, reflection, skills developed through practice, and self-knowledge such as attitudes, values, and emotions.

The RCGP curriculum reflects all three types but emphasizes personal knowledge and capability as most crucial for effective practice. They define capability as a doctor’s ability to practice safely and effectively, demonstrating the necessary skills, knowledge, and professional attitudes.³ 

A critical but often overlooked question is: how do we justify what we know? Codified knowledge is typically justified using academic standards of truth, but practitioners are often more concerned with practical relevance. From an epistemological perspective, medical knowledge is seen as a practical science, consisting of hypotheses and rules where truth is often ‘system-relative’ and not always philosophically verifiable.³ Evidence-based medicine (EBM) tries to provide research-based guidelines, but only about 20% of medical decisions are covered by the highest level of evidence (meta-analyses of randomized controlled trials).⁴  This limitation is unsurprising, as such standards are often unsuitable for the complexity and uncertainty inherent in general practice.

The extent to which cultural knowledge is amenable to codification is open to debate. Whereas codified cultural knowledge is often discussed in terms of its truth and validity, uncodified cultural knowledge is often discussed in terms of ownership, location, and history.

Justifying personal knowledge differs again. Personal knowing is rooted in lived experience and produces understandings and actions that are perceptual and often imprecise. Aristotle referred to this as phronesis—practical wisdom developed through being, relating, and acting,⁵ that we might apply within the context of general practice. This type of knowledge involves considering both individual and social perspectives, recognizing that individuals both shape and are shaped by the knowledge of others, often within contexts influenced by power dynamics.

When justifying personal knowledge, several issues must be considered:

• Reliability: Does the knowledge consistently lead to true beliefs or effective actions?
• Transferability: Can aspects of this knowledge be shared or taught, even if it requires making tacit knowledge explicit?
• Improvement: Are we able to critically examine and recognize the limitations of our personal understanding?
• Credibility: Can we provide plausible explanations for our knowledge and actions to others?

Justification of personal knowledge involves both internal and external factors:

• Experience and Practice: Success and effectiveness in practice can justify personal knowledge, especially when it consistently leads to desired outcomes across diverse situations.
• Reflective Practice: Introspection and reflection help find patterns and principles underlying personal knowledge. Feedback, both internal and external, refines and strengthens it.
• Coherence and Consistency: Personal knowledge should be internally consistent and narratively coherent, meaning we can explain how we got it and why it works.
• Social and Interpersonal Justification: Testimony, consensus, and peer recognition can confirm personal knowledge, as can mentorship and apprenticeship, which help the transfer and justification of tacit knowledge.
• Connection to Explicit Knowledge: Personal knowledge can sometimes be justified by linking it to established theories or explicit knowledge, and efforts to articulate it can further strengthen its justification.

Developing the capacity to justify personal knowledge requires self-awareness, cultural awareness, recognition of bias, and the ability to make research-informed decisions. While formal teaching plays a role, this capacity evolves through guided reflection. Reflective processes should include reflexivity, which helps elucidate implicit cultural values.⁶

A practical method is to use guided reflection on cases and events from practice to analyse existing knowledge and skills, find gaps, and set learning goals. This process should include reviewing both successful and uncertain cases, using internal and external justification factors. Activities such as seeking peer recognition and consensus can further support justification. Evaluation occurs on review of performance when similar cases and situations are faced in future practice. Reviewing and documenting the process, for example in a reflective journal, promotes coherence and can be used for accreditation purposes.

The justification of knowledge in general practice is a complex, ongoing process that integrates codified, cultural, and personal knowledge. It relies on reflective practice, social validation, and the ability to connect personal insights to broader professional standards.

References

1. Eraut M. Developing Professional Knowledge and Competence. Third Edition Routledge Falmer, Oxon. 2006
2. Eraut, M. Developing knowledge for qualified professionals. In M. Jones, O. McNamara, & J. Murray (Eds.), Workplace learning in teacher education (pp. 47–72). Dordrecht: Springer
3. https://www.rcgp.org.uk/mrcgp-exams/gp-curriculum [accessed 19/10/25]
4. Sadegh-Zadeh, K. The Semantics and Pragmatics of Medical Knowledge in Handbook of analytic philosophy of medicine. 479-550, Second Edition. Dordrecht:  Springer, 2015.
5. Eraut, M. (2000), Non-formal learning and tacit knowledge in professional work. British Journal of Educational Psychology, 70: 113-136. https://doi.org/10.1348/000709900158001
6. The Nicomachean ethics. Books I-X. London: Oxford University Press. 1975.
7. Goldie J. Do training and CPD foster truly reflective GPs? Br J Gen Pract. 2017 Feb;67(655):83. doi: 10.3399/bjgp17X689305. PMID: 28126878; PMCID: PMC5308112. https://bjgp.org/content/67/655/83.long [accessed 19/10/25]

Featured Photo by Kenny Eliason on Unsplash