Though both psychology and logic treat of the knowing aspect of the mind, yet the fields are not identical. The former deals with the _process_ of the knowing mind as a _whole_, while the latter is concerned mainly with the _product_ of the knowing mind when it _thinks_. To be specific: The mind knows when it becomes aware of anything, moreover, this condition of awareness appears in two ways: first, immediately or by _intuition_; second, after deliberation or by _thinking_. For example, one may know immediately or by intuition that the object in the hand is a lead pencil, but when requested to state the length of the pencil there is deliberation involving a comparison of the unknown length with a definite measure. It may now finally be asserted that the pencil is six inches long. When we know without hesitation the process involved is intuition, whereas when the knowledge comes after some sort of comparison the mental act is called thinking. It, therefore, becomes the business of psychology to deal with both intuition and thinking while logic devotes its attention to thinking only, and even in this field the work of logic is more or less indirect. The specific scope of logic is the product of thinking or thought.[1] What are the forms of thought? What are the laws of thought? Are the several thoughts true? These are the questions which logic is supposed to answer.
For the logician thought has two sources, his own mind and the mind of others. In the latter case thought becomes accessible through the medium of language. There is in consequence a close connection between logic, the science of thought, and grammar, the science of language. Because of this near relation logic is sometimes called the “grammar of thought.”
To study any science properly one must have thoughts and since logic is the science of all thought the subject may be regarded as the _science of sciences_.
“Logic is the science of thought.” This definition commonly given is too brief to be helpful. Should not a definition of any subject represent a working basis upon which one may build with some knowledge of what the structure is to be? The following, a little out of the ordinary, seems to supply this condition: _Logic as a science makes known the laws and forms of thought and as an art suggests conditions which must be fulfilled to think rightly._