all intents and purposes is colourless, redundant and hackneyed. Almost any other expression would be an improvement. 'He is, to all intents and purposes, king of the island' {Mail on Sunday} would be instantly made better by changing the central phrase to 'in effect' or removing it altogether. If the phrase must be used at all, it can always be shorn of the last two words. 'To all intents' says as much as 'to all intents and purposes'.
( Bill Bryson )
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