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When we speak of the principles of causality, we do not mean that 
every event has a cause, but that every event must have a cause. Where 
do you get the “ must ” ? (Applause.) It seems to me to be implied 
in this question. Suppose the experience of various phenomena suggested 
the general idea of a cause, how come we by the previous thought that 
there should be a cause ? It was said that the word prior is understood, 
but there are two meanings in which you may take the word “ prior ” ; 
prior in time or prior in logic. You suppose that there is a notion 
of causality before a previous thought. Here, “ that there should be a cause,’’ 
means not previous in time but in logic, and that would bring out the point 
I was speaking of, namely, How do you get this notion of causality ? You 
cannot draw it out by empirical consciousness. It would seem to point to 
the higher consciousness of which I was speaking ; but, as I have said, my 
views are not yet matured upon that point. (Applause.) 
Dr. Edward Haugiiton.— May I ask if it is the intention of Dr. Irons in 
his second paper to take any notice of the philosophy of Dr. Hartley, who 
held similar views on necessity to those Dr. I,rons has referred to in the first 
part ? Dr. Hartley was a voluminous and an able writer, although he is 
now somewhat out of date, particularly in physiology, yet being a con- 
temporary of Locke, and holding, to a certain extent, a similarity of views, 
he received more or less support from Locke. It would, therefore, be very 
desirable if some notice could be taken of his system of philosophy, more 
especially as he was not a Pantheist but a religious and pious man. 
Mr. Reddie. — I think we should allow Dr. Irons to pursue his own course ; 
but perhaps Dr. Haughton would himself favour us with a paper upon the 
philosophy to which he has referred. 
Dr. Haughton. — I only asked for information. I am not aware whether 
he is referred to or not, but I trust he will not be overlooked or thought 
unworthy of notice, though I am far from holding his opinions. 
The Chairman. — The usual custom is for the Chairman to express his 
own views on the paper, and as it were in some degree to sum up the 
arguments before the writer replies, in order that he may have a full 
opportunity of replying to everything that has been said. I cannot venture 
to criticise in any way a paper in which I so thoroughly agree ; at the same 
time I think that we are very much indebted to Dr. Rigg for so powerfully 
putting forward his reasons for considering that Dr. Irons is out of date in 
his metaphysics. A great deal, however, may be said in his favour, and I 
cannot help feeling that one great merit among others of this paper is the 
mode in which Dr. Irons has treated the subject. There is a very vague 
idea — I call it a vague one, but it is an idea very prevalent, owing to the 
superficial thoughts of people in every branch of philosophy, — that there is 
a much more certain degree of evidence to be acquired in what is called 
physical philosophy (I mean phenomena and the causes of the phenomena of 
the material world) — that there is much surer and more certain demonstration 
to be obtained on such subjects, than upon such a question as Dr. Irons has 
brought before us, that of moral responsibility. I cannot but feel that Dr. 
