The Meaning of Psychology
The word psychology comes from two Greek words: psyche, meaning soul, mind, or self, and logos, meaning science, study, or investigation. Put together, psychology literally means the study of the soul or mind. In practical terms, psychology investigates mental processes and how they show up in the way people and animals relate to one another socially — which is why it’s often summarised as the science of soul.
The term itself is relatively recent as far as formal usage goes: it was first used in 1590 by Rudolf Gockel. Since then, psychology has taken on real importance precisely because it gives us insight into the human mind and the logic behind human behaviour in social settings.
How the Definition of Psychology Evolved
Psychology hasn’t always meant what it means today. As the field matured, thinkers kept redefining what psychology was actually the ‘science of’ — and each redefinition reflects a real shift in how seriously the discipline could be studied scientifically.
| Era / Definition | Key Figures | Core Idea |
| Science of the Soul | Plato, Aristotle (ancient Greek philosophers) | Psychology was treated as a branch of philosophy, studying the soul. But since soul is metaphysical, it cannot be seen, observed, or tested — so this definition couldn’t support real scientific experiments. |
| Science of the Mind | Immanuel Kant (German philosopher); William James (1892) | Kant defined psychology as the science of the mind. James later called it the science of mental processes. But ‘mind’ proved just as ambiguous as ‘soul’ — its nature and functions were unclear and disputed. |
| Science of Consciousness | James Sully (1884); Wilhelm Wundt (1892) | Modern psychologists redefined it as the science of consciousness. Sully called it the ‘science of the inner world’; Wundt described it as the study of ‘internal experiences’. This still ran into trouble, since consciousness itself has three levels — conscious, subconscious, and unconscious — so the definition wasn’t fully accepted either. |
| Science of Behaviour | J.B. Watson (popularised the term); William McDougall; W.B. Pillsbury | At the start of the 20th century, psychologists pushed to make the field a pure science, and redefined it as the science of behaviour — something that could actually be observed and measured, unlike soul, mind, or consciousness. |
R.S. Woodworth summed up this whole evolution memorably: psychology first lost its soul, then lost its mind, then lost its consciousness — but it still has behaviour, of a sort. That line captures exactly why ‘science of behaviour’ became the most workable definition: it’s the one thing about the mind that can actually be observed from the outside.
Formal Definitions Worth Knowing
Beyond the historical evolution, a few formal definitions are worth holding onto, since different psychologists emphasised different things:
| Definition | Proposed By |
| “Psychology is the science of behaviour and experience.” | B.F. Skinner |
| “Psychology is the study of human behaviour and human relationships.” | Crow and Crow |
| “Psychology is the scientific study of the behaviour of living creatures in their contact with the outer world.” | Kurt Koffka |
Notice the common thread: all three modern definitions anchor psychology to behaviour — something observable — rather than to soul, mind, or consciousness alone, which is exactly the shift the historical evolution above was building toward.
The Branches of Psychology
Psychology today is broad enough that it splits into many specialised branches. Each branch looks at human thought and behaviour from a different angle, but all of them share the same underlying goal: understanding and explaining why people think, feel, and act the way they do.
| Branch | What It Studies |
| Abnormal Psychology | Psychopathology and abnormal behaviour; assessing, diagnosing, and treating psychological disorders such as anxiety and depression. Counsellors, clinical psychologists, and psychotherapists work directly in this field. |
| Behavioral Psychology | Also called behaviourism — the theory that all behaviours are acquired through conditioning. It dominated psychology in the early 20th century and, although less central after the 1950s, its techniques remain a mainstay in therapy and education. |
| Biopsychology | How the brain, neurons, and nervous system influence thoughts, feelings, and behaviours; draws on biology, physiology, cognitive psychology, and neuroscience. |
| Clinical Psychology | Assessment and treatment of mental illness, abnormal behaviour, and psychiatric disorders; clinicians work in private practice, community centres, and universities. |
| Cognitive Psychology | Internal mental states — how people think, learn, and remember. This branch has grown continuously since it emerged in the 1960s. |
| Comparative Psychology | The study of animal behaviour, used to build a deeper and broader understanding of human psychology by comparison. |
| Counseling Psychology | One of the largest subfields; centred on treating clients experiencing mental distress and a wide variety of psychological symptoms. |
| Developmental Psychology | How people change and grow throughout life — physical growth, intellectual development, emotional change, social growth, and perceptual change across the lifespan. |
| Educational Psychology | Schools, teaching, educational issues, and student concerns; educational psychologists study how students learn and work directly with students, parents, teachers, and administrators. |
| Forensic Psychology | Issues at the intersection of psychology and the law — applying psychological principles to legal issues, criminal behaviour, and treatment, sometimes working directly within the court system. |
