  The paper analizes a set of issues related to analogy and analogical
reasoning, namely: 1) The problem of analogy and its duplicity; 2) The role of
analogy in demonstrative reasoning; 3) The role of analogy in non-demonstrative
reasoning; 4) The limits of analogy; 5) The convergence, particularly in
multiple analogical reasoning, of these two apparently distinct aspects and its
methodological and philosophical consequences. The paper, using example from
number theory, argues for an heuristc conception of analogy.
