Instinkt und Gewohnheit

"Lloyd Morgan's contribution was indeed so outstanding as to warrant our considering him as one of the founding fathers of both comparative psychology and ethology. He wrote fourteen substantial books and we can do little more here than indicate very briefly the variety of topics which he illuminated and advanced by his studies. First, he had valuable points to make on the relations between the subjective and the objective approach. In short, he indicates that both are essential to the scientific method (Introd. Comp. Psychol., 1894). Then he investigated the nature versus nurture problem, concluding (in opposition to Wundt) that from a biological point of view one should restrict the term 'instinctive' to what is, to a greater or lesser degree, congenitally determined.
In this he strongly supported the view that instinct is fundamentally species-specific behaviour (Habit and Instinct, 1896). As to the evolution of behaviour, his advice was 'stick to Observation and leave theorizing about the process of evolution to "armchair philosophers" ' (Life, Mind and Spirit, 1925). This was remarkable when we consider that his basic approach was that of a philosopher.
He stressed the need for operational definitions, that is, he emphasized the importance of stating definitions specifically, and if possible operationally, since lack of such care can lead to misinterpretation and misconception (Habit and Instinct, 1896).
He invented the term 'trial and error' as applied to learning, although for a while he spoke of 'trial and failure' and 'trial and practice'; he also made original observations on the behaviour of dogs and it was upon these that his conclusions, set out in Animal Behaviour (1900) and The Animal Mind (1930), were based."

From: Thorpe, W. H. (1979) "The origins and rise of ethology."