From the foregoing discussions it must not be deduced that because of the specific nature and the difficulty of thinking that the power is given only to adults.  On the contrary, the power is rooted in the original equipment of the human race and develops gradually, just as all other original capacities do.  Children under three years of age manifest it.  True, the situations calling it out are very simple, and to the adult seem often trivial, as they most often occur in connection with the child’s play, but they none the less call for the adjustment of means to end, which is thinking.  A lost toy, the absence of a playmate, the breaking of a cup, a thunderstorm, these and hundreds of other events of daily life are occasions which may arouse thinking on the part of a little child.  It is not the type of situation, nor its dignity, that is the important thing in thinking, but the way in which it is dealt with.  The incorrectness of a child’s data, their incompleteness and lack of organization, often result in incorrect conclusions, and still his thinking may be absolutely sound.  The difference between the child and the adult in this power is a difference in degree—­both possess the power.  As Dewey says, “Only by making the most of the thought-factor, already active in the experience of childhood, is there any promise or warrant for the emergence of superior reflective power at adolescence, or at any later period."[7]

Thinking, then, is involved in any response which comes as a result of the conscious adaptation of means to end in a problematic situation.  Many of the processes of mental activity which have been given other names may involve this process.  Habit formation—­when the learner analyzes his progress or failure, when he tries to find a short cut, or when he seeks for an incentive to insure greater improvement—­may serve as a situation calling for thinking.  The process of apperceiving or of assimilation may involve it.  Studying and trying to remember may involve it.  Constructive imagination often calls for it.  Reasoning, always requires it.  In the older psychology reasoning and thinking were often used as synonyms, but more recently it has been accepted by most psychologists that reasoning is simply one type of thinking, the most advanced type, and the most demanding type, but not the only one.  Thinking may go on (as in the other processes just mentioned) without reasoning, but all reasoning must involve thinking.  It is this lack of differentiation between reasoning and thinking, the attempt to make of all thinking, reasoning, that has limited teachers in their attempts to develop thinking upon the part of their pupils.