Page:Philosophical Transactions - Volume 053.djvu/441

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Mr. Bayes has thought fit to begin his work with a brief demonſtration of the general laws of chance. His reaſon for doing this, as he ſays in his introduction, was not merely that his reader might not have the trouble of ſearching elſewhere for the principles on which he has argued, but becauſe he did not know whither to refer him for a clear demonſtration of them. He has alſo made an apology for the peculiar definition he has given of the word chance or probability. His deſign herein was to cut off all diſpute about the meaning of the word, which in common language is uſed in different ſenſes by perſons of different opinions, and according as it is applied to paſt or future facts. But whatever different ſenſes it may have, all (he obſerves) will allow that an expectation depending on the truth of any paſt fact, or the happening of any future event, ought to be eſtimated ſo much the more valuable as the fact is more likely to be true, or the event more likely to happen. Inſtead therefore, of the proper ſenſe of the word probability, he has given that which all will allow to be its proper meaſure in every caſe where the word is uſed. But it is time to conclude this letter. Experimental philoſophy is indebted to you for ſeveral diſcoveries and improvements; and, therefore, I cannot help thinking that there is a peculiar propriety in directing to you the following eſſay and appendix. That your enquiries may be rewarded with many further ſucceſſes, and that you may enjoy every every valuable bleſſing, is the ſincere wiſh of, Sir,

your very humble ſervant,

Newington-Green, Nov. 10, 1763.
Richard Price.