24 
POLITICAL ECONOMY 
experience, and is bound to lead to error 
—so it is alleged. It is no less mistaken 
than to think of the brain as related to the 
lungs and heart as one stone is related to 
another in a heap by the road-side. The 
only possible social law, it is asserted, must 
be of such a form as to connect the whole 
state of society at one time with its whole 
state at another time. 
This line of argument is so plausible and 
embodies so much truth that those who are 
converted by it may well be excused. But 
the more persistent of those who are predis 
posed to believe that a rationalistic account 
—which may not be the whole account— 
of all experience is possible will more closely 
scrutinise what is supposed to block their path. 
On doing so they will detect first that the 
arguments opposed to them prove too much. 
If they are through and through sound all 
the biological sciences are in a quandary ; 
but we know they have been successful in 
framing convincing generalisations relating to 
the facts of life. The reason for their success 
is that the mental abstraction of one thing 
from another is possible even when the phy 
sical separation of the one thing from the other 
is not feasible ; and experience, which is the 
ultimate test of the correctness of all laws,