In the wake of a G20 protest that involved quite a bit of unfenestration, I felt moved to say briefly why this particular tactic leaves me decidedly uneasy. Note this is a question of strategy, not of legitimacy.
1) The whole point of the tactic, and of the movement it’s an expression of, is to re-draw lines of solidarity. Instead of “normal people+police+companies vs. freaks+loonies”, it should be “normal people+freaks+loonies vs. police+companies”. The idea is that breaking the windows of Starbucks or BMO is not ‘anti-social’ (hostile to everyone) but merely ‘anti-capital’ (hostile to one class, but friendly to everyone else).
2) It’s really difficult to convey the distinctions one is drawing. It happens quickly, without explanatory ‘why we just broke your windows’ leaflets, without announcement or publicity in advance. So all that’s visible is that some windows got broken and some didn’t, but not the rule according to which that was decided. Did that clothing store get hit because it’s a big multinational company, because of its advertising campaigns, because of its labor policies, or just because it’s a capitalist company?
3) There is no shortage of people out to reinforce the ‘common-sense’ lines of sympathy, to describe window-smashing as ‘violence’, as a threat to ‘the public’, etc.
Upshot: given the usual context, it’s really hard to carry out the sort of window-smashing that would make sense – namely, one in which ‘we’ (normal people+freaks+loonies) express our power over ‘their’ property, rather than ‘them’ (freaks+loonies) attacking ‘ours’.