Evolution of Concepts: From Causalism to Reactivity
Historically, two polarized schools of thought emerged in medicine. The first is causalism (from Latin causalis — causal). In the 19th century, Claude Bernard put forward the idea that every disease has a specific cause, but its manifestation requires certain objective conditions. Later, in the 1870s, amidst the rapid development of microbiology and Louis Pasteur's discoveries, monocausalism arose. Its core premise was that any disease has only one cause — a bacterium — while environmental conditions were considered secondary and insignificant.
However, monocausalism soon faced a severe crisis. It became clear that the mere presence of a microorganism in the body was insufficient for a disease to develop. The phenomena of bacterial carriage and dormant infection were discovered. It became evident that different people react completely differently to the same pathogen under identical conditions. This led to a crucial shift: scientists' attention turned to studying the reactivity of the organism, which ultimately launched the study of allergy.
Conditionalism and the Denial of Cause
As a reaction to the clear shortcomings of causalism, a second school of thought emerged — conditionalism (from Latin condicio — condition). Its founder was the 19th-to-20th-century German philosopher Max Verworn.
The essence of this theory was the complete denial of the very cause of diseases. Conditionalists recognized exclusively the conditions of their occurrence. Furthermore, this approach focused primarily on subjective conditions, while crucial socio-economic factors were often simply excluded from the analysis.
Verworn's main postulates stated that the concept of 'causality' should be entirely eliminated from scientific thinking and replaced with abstract mathematical concepts. Disease, in his view, is associated with a complex of various conditions. Verworn believed that a physician must know three basic things: the conditions of health (to maintain them) and the conditions for the development of diseases (to prevent or treat them).
Modern Concepts of Disease Onset
Modern medicine has found a balance, viewing disease as the result of a complex interaction between cause and conditions. The mechanism of pathological development is triggered when, under the influence of a cause and specific conditions, homeostasis—the body's equilibrium with the external environment—is disrupted. The core of this process lies in the inadequacy of the body's adaptability (adaptation) to environmental factors.
Living conditions influencing this process are divided into two groups:
- External environment: social, geographical, biological, and physical factors.
- Internal environment: conditions arising within the body itself (e.g., heredity and constitution).
Interestingly, in cases where the true cause of a disease remains unknown, modern medicine is forced to rely on conditionalism, focusing specifically on the conditions that foster the pathology's development.
Clinical Significance of Etiology
A key postulate of modern general pathology is: there can be no disease without a cause. The cause determines the specificity (qualitative features) of a specific disease. Causes can be external (environmental factors) and internal (genetic defects, congenital malformations).
To date, etiology is well understood for most infectious and endocrine diseases, as well as trauma. However, a vast array of diseases has an undetermined etiology: psychiatric disorders, malignant tumors, atherosclerosis, sepsis, and sarcoidosis.
Knowledge of etiology is critically important for clinical practice:
- Etiological treatment: aimed at the complete eradication of the cause. This is the most effective approach if the cause is known.
- Role of conditions: understanding conditions explains individual patient reactivity (why some fall ill under identical exposure while others do not).
- Treatment without knowing the cause: even if etiology is unknown, successful treatment is possible by targeting the mechanisms of development (pathogenesis). A prime example is appendicitis: its clinical presentation, course, and outcomes are well understood, and surgical treatment is standardized, yet the exact etiology remains unestablished.