1. To the degree or extent that; insofar as. We might as well have been educated by dogs for all the good their teaching did! For all I know, she could be living in Timbuktu by now!
2. In spite of; notwithstanding. For all our efforts to stop the bill, it still cleared both the House and the Senate with ease.
See also: all
1 in spite of...: For all his qualifications, he isn’t really very good at the job. ♢ For all her claims to be efficient, she is a very slow worker.
2 used for saying that the thing you mention does not matter or make any difference: He can do what he wants, for all I care (= I don’t care what he does). ♢ ‘Where’s Peter?’ ‘For all I know, he may be dead.’