124 JOURNAL OF THE PLYMOUTH INSTITUTION. 
that such is the case ; it will then only warrant us in applying the 
results over the same ground as that covered by the experience 
from which it was collected. 
Mr. Mill does indeed admit as much, when, after saying {Logic, 
vol. ii. p. 103) " The law of cause and effect being thus certain, is 
capable of imparting its certainty to all other inductive pro- 
positions which can be deduced from it," he goes on to say (p. 
106), " It must at the same time be remarked, that the reasons for 
this reliance do not hold in circumstances unknown to us, and 
beyond the possible range of our experience. In distant parts of 
the stellar regions, where the phenomena may be entirely unlike 
those with which we are acquainted, it would be folly to affirm 
confidently that this general law prevails, any more than those 
special ones which we have found to hold universally on our own 
planet. The uniformity in the succession of events, otherwise 
called the law of causation, must be received not as a law of the 
universe, but of that portion of it only which is within the range 
of our means of sure observation, with a reasonable degree of 
extension to adjacent cases. To extend it further is to make a 
supposition without evidence, and to which, in the absence of any 
ground from experience for estimating its degree of probability, it 
would be idle to attempt to assign any." 
If then it be idle to apply the law of causation to regions which 
distance in space hides from our view, how are we warranted in 
applying it (except only as a probability) to those regions which 
time prevents us from examining — the events of the future and 
pre-historic past ? 
The fact indeed appears to be, that we are strictly warranted in 
claiming only a degree of probability for any knowledge that we 
possess of even the existence of the exterior world (as the supposed 
cause of our sensations), which has resulted from an experience as 
yet unfinished, and that we are even precluded from forming any 
estimate of what this degree of probability may be as related to 
certainty, which would be the result of an induction from an 
eternity of all experience past and future, and co-extensive with 
all space. Even the Law of Causation and the proposition which 
affirms the existence of matter can be only held as provisionally 
true, but are not capable of demonstration, as is a purely mathe- 
matical proposition. Still we can estimate the relative degrees of 
probability which such propositions possess among themselves ; and 
