2.  A  synthetical  proposition,  on  the  other  hand,  is
one  in  which  the  predicate  is  not  contained  in  the
subject,  but  adds  to  it  some  fresh  quality,  or  attri-
bute, which  an  analysis,  however  minute,  could
never  have  discovered  in  it.  Such  propositions  are
sometimes  called  ampliative,  because  they  enlarge
our  stock  of  knowledge.  When,  for  instance,  I  say
that  Canvas-backed  ducks  are  found  in  Maryland,  or
that  Fools  are  known  by  the  multitude  of  their  words,
I  am  adding  to  the  ideas  of  canvas-backed  ducks
and  fools  what  no  mere  analysis  could  have  revealed
in  them.  They  convey  into  my  mind  fresh  know-
ledge from  outside,  requiring  experience  and  obser-
vation. These  propositions  are  called  synthetical,
because  they  synthesize,  or  put  together,  the  inde-
pendent ideas  contained  in  the  subject  and  predicate
respectively.  They  proceed  from  the  simple  to  the
composite.  They  do  not  make  use  of  materials
existing  within  our  minds,  but  they  introduce
fresh  materials  which  no  amount  of  thinking  could
have  thought  out  from  the  stock  of  knowledge
already  possessed.  They  cannot  be  reduced  to
the  primary  law  given  above,  but  are  regulated  by
another  code  of  law  belonging  to  material  logic.
They  may  be  universally  true,  but  their  universality
does  not  depend  on  any  primary  law  of  thought.
Thus  the  proposition,  All  men  are  mortal,  is  a
synthetical  proposition,  because  the  idea  of  humanity
does  not  contain  the  idea  of  mortality.  As  a  matter
of  fact,  all  men  are  subject  to  death,  but  it  is


THE  FOUNDATIONS   OF  LOGIC.
quite  conceivable  that  some  healing  remedy  might
have  been  provided  which  would  have  averted  death
until  the  time  of  their  probation  was  over,  and  that
then  they  would  have  passed  into  a  different  state  of
existence,  where  death  is  unknown  and  impossible.
