GENERAL VIEW OF NATURE AND SCOPE OF LOGIC. 19 



of things that we can arrive at scientific knowledge, and ultimately 

 at that higher unification of the special sciences which we call 

 philosophy. N ow this method by which we proceed to amass and 

 arrange our knowledge will be found to be twofold deductive or 

 synthetic, and inductive or analytic according to the side from 

 which we can best approach the subject-matter of any special in 

 vestigation. If the subject-matter can be best approached from 

 an intellectually abstract point of view, through the medium of a 

 few great, broad, general truths, as is strikingly the case in the 

 pure mathematical sciences, the deductive method w\\\ be employed ; 

 if on the contrary the subject-matter be presented to us through 

 our senses, in the shape of innumerable individual, concrete facts 

 or phenomena, as is obviously the case in the physical, experi 

 mental sciences, then the method used will be the inductive method. 

 Hence a fourth section of logic will deal with Method, Deductive 

 and Inductive. 



The various sections just outlined will analyse our thinking 

 processes with a view to the formulation of rules and laws, the 

 observance of which will secure correct thinking and safeguard 

 our rational investigations from error. As the aim of logic is to 

 teach us how to reach scientific knowledge with certitude we 

 must next inquire into the nature and requirements of science, 

 proof and explanation. Since, however, it is not always possible 

 to reach certain knowledge, we must analyse the nature and 

 conditions of probability. And since the snares and pitfalls to 

 which reason is naturally exposed are so numerous and so difficult 

 to avoid, it will add to the practical utility of logic to reconnoitre 

 again the ground already traversed, for the purpose of calling 

 explicit attention to all such dangers. Hence the closing section 

 on Certitude, Probability, Error and Fallacies. 



10. FORMAL VALIDITY OR CONSISTENCY, AND MATERIAL 

 VALIDITY OR TRUTH, OF THOUGHT : DIFFERENT VIEWS AS TO 

 SCOPE OF LOGIC. Let us next consider a little more fully what 

 people usually mean by correct or accurate and incorrect or inac 

 curate thinking, by valid and invalid thought, by true and false or 

 erroneous knowledge. About the meaning of terms true and false 

 (or erroneous] there can be hardly room for ambiguity. Know 

 ledge is commonly understood to be true if it is in conformity with 

 its object, with the thing or reality about which it is concerned ; to 

 be false if at variance with the facts, with the actual state of affairs, 

 with the thing or reality in question. We may let that clear and 



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