PREFACE TO THIRD EDITION 



?HE present edition has been revised throughout, and in fact 



written. Three chapters are new, viz. the fifth (On the 

 onception of Randomness) and the eighteenth and nine- 



ienth (On the nature, and on the employment, of Averages), 

 he eighth, tenth, eleventh, and fifteenth chapters have been 



icast, and much new matter added, and numerous altera- 

 Lons made in the remaining portions 1 . On the other hand 

 hree chapters of the last edition have been nearly or 

 ntirely omitted. 



These alterations do not imply any appreciable change of 

 lew on my part as to the foundations and province of 

 robability. Some of them are of course due to the necessary 

 Ganges involved in the attempt to write up to date upon a 

 ibject which has not been stationary during the last eleven 

 ra. For instance the greatly increased interest now 

 iken in what may be called the Theory of Statistics has 



ndered it desirable to go much more fully into the Nature 

 ad treatment of Laws of Error. The omissions are mainly 



1 I have indicated the new chapters and sections by printing them in 

 lies in the Table of Contents. 



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