214 MYSTICISM AND LOGIC 



Among universals I include all objects of which no par- 

 ticular is a constituent. Thus the disjunction " universal- 

 particular " includes all objects. We might also call it the 

 disjunction ** abstract-concrete." It is not quite parallel 

 with the opposition " concept-percept," because things 

 remembered or imagined belong with particulars, but can 

 hardly be called percepts. (On the other hand, universals 

 with which we are acquainted may be identified with 

 concepts.) 



It will be seen that among the objects with which we 

 are acquainted are not included physical objects (as 

 opposed to sense-data), nor other people's minds. These 

 things are known to us by what I call " knowledge by 

 description," which we must now consider. 



By a " description " I mean any phrase of the form " a 

 so-and-so " or "the so-and-so." A phrase of the form 

 "a so-and-so " I shall call an " ambiguous "description ; 

 a phrase of the form " the so-and-so " (in the singular) I 

 shall call a " definite " description. Thus " a man " is 

 an ambiguous description, and *' the man with the iron 

 mask " is a definite description. There are various 

 problems connected with ambiguous descriptions, but I 

 pass them by, since they do not directly concern the matter 

 I wish to discuss. What I wish to discuss is the nature of 

 our knowledge concerning objects in cases where we know 

 that there is an object answering to a definite description, 

 though we are not acquainted with any such object. This 

 is a matter which is concerned exclusively with definite 

 descriptions. I shall, therefore, in the sequel, speak 

 simply of ** descriptions " when I mean " definite descrip- 

 tions." Thus a description will mean any phrase of the 

 form " the so-and-so " in the singular. 



I shall say that an object is " known by description " 

 when we know that it is " the so-and-so," i.e. when we 



