attr_accessor default values

Rails has attr_accessor_with_default so you could write

class Like
  attr_accessor_with_default :politics,false
end

i = Like.new
i.politics #=> false

and thats all

UPDATE

attr_accessor_with_default has been deprecated in Rails 3.2.. you could do this instead with pure Ruby

class Like
  attr_writer :politics

  def politics
    @politics || false
  end
end

i = Like.new
i.politics #=> false