Expressing values

So I was chatting to my brother Screwy over Christmas, and he asserted that making ethical consumer choices is just a way to express your values, it doesn't really help to bring about change. Now, Screwy is a philosopher and fond of making provocatively sweeping statements, and he's also way to the left of me politically. But when we were chewing over this one, I realized I couldn't entirely refute it. So I'm bringing it to DW, to see what my thinky interesting readers think.

( of course, I can never just make a statement without babbling about it )

Well, last time I talked about the philosophy behind my politics it went reasonably well, so let's see if this sets off some equally good discussion, even if I am not quite aligned with many of my readers in some ways.

ETA: My brother turned up to explain what he meant a bit more clearly than my summary: his clarification