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  predisposed ­
  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  physical ­
  separation  of  the  one  thing  from  the  other
is  not  feasible  ;  and  experience,  which  is  the
ultimate  test  of  the  correctness  of  all  laws,