3. LOGIC DEFINED.
“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.
In justification of the latter definition it may be argued that it covers the topics usually treated by logicians. It is said that a science teaches us to know while an art teaches us to do. As a science logic teaches us to know certain laws which underlie right thinking. For example, the law of identity which makes possible all affirmative judgments, such as “Some men are wise,” “All metals areelements,” etc. Likewise as a science logic acquaints us with certain universal forms to which thought shapes itself, such as definitions, classifications, inductions, deductions. Further, logic lays down definite rules which lead to right thinking. To wit: Because it is true of a part of a class it should not be assumed that it is true of the whole of that class: or, in short, do not distribute an undistributed term.
A possible profit to the student may result from a study of certain authentic definitions herewith subjoined:
(1) “Logic is the science of the laws of thought.” Jevons.
(2) “Logic is the science which investigates the process of thinking.” Creighton.
(3) “Logic as a science aims to ascertain what are the laws of thought; as an art it aims to apply these laws to the detection of fallacies or for the determination of correct reasoning.” Hyslop.
(4) “Logic is the art of thinking.” Watts.
(5) “Logic is the science and also the art of thinking.” Whateley.
(6) “Logic is the science of the formal and necessary laws of thought.” Hamilton.
(7) “Logic is the science of the regulative laws of the human understanding.” Ueberweg.
(8) “Logic treats of the nature and of the laws of thought.” Hibben.
(9) “Logic may be defined as the science of the conditions on which correct thoughts depend, and the art of attaining to correct and avoiding incorrect thoughts.” Fowler.
(10) “Logic is the science of the operations of the understanding which are subservient to the estimation of evidence.” Mill.
(11) “Logic may be briefly described as a body of doctrines and rules having reference to truth.” Bain.
It would seem as if there were as many different definitions as there are books on the subject. This is due partly to the disposition of the older logicians to ignore the art of logic and partly to the difficulty of giving in a few words a satisfactory description of a broad subject. In the fundamentals of logical doctrine present-day authorities virtually agree.