This post was inspired by a discussion on Common Sense Atheism this week, in which Luke Muehlhauser examines a longstanding debate between me and Massimo about morality. There are several aspects of Massimo's position that I disagree with, but as Luke astutely notes, one of the main ones results from what I consider a fundamentally misguided way of using definitions. I've been wanting to highlight this issue for a while, because it keeps coming up in other debates we've had on other topics – so, taking Luke's post as an invitation, I'll do so now.
But you have to be careful when you establish that definition, the SYMBOL = CONCEPT relationship, that you're not implicitly thinking of the symbol as having another, hidden concept inside it already. Because if you are, then what you're doing is actually equating one concept with another, different concept. That's not a definition, that's a claim, and it can be incorrect.