Last year someone asked on Stackoverflow about using 'type=bool'.  My answer is at:

http://stackoverflow.com/questions/15008758/parsing-boolean-values-with-argparse/19233287#19233287

'type' is supposed to be a function that takes a string, and converts to a desired Python object (e.g. number), and in the process validates it.

The builtin 'bool()' is not a good choice for this. 'bool("")' returns False, all other strings return True, that includes strings like "false", "no", "False".  If you want those strings to be interpreted as boolean False, you need to write your own 'str2bool' function.

But normally boolean values are entered via 'store_true' and 'store_false' actions.