Overidding default values of inherited tables

Please let me know how to overide the DEFAULT value in
inherited tables?
(using PG 7.0.2)

create table objects (
id serial,
type name DEFAULT 'object'
);

create table books (
title name,
-- type name DEFAULT 'book' <--- how to do?
) inherits(objects);

create table hats (
color name,
-- type name DEFAULT 'hat' <--- how to do?
) inherits(objects);

PG tells me I cannot redefine the attribute "type",
right, but how about redefining the default value...