We've all heard that the main character in a book should want something (and ideally, that the other characters should want something, too). But some critique feedback I got recently made me ponder the question: Do we have to know why the character wants it?
I threw out the question on Twitter and, although that's hardly a scientific poll, the responses I got were overwhelmingly YES. There were qualifications, caveats, and exceptions: We may not need to be told outright, but we should be able to figure it out. If the goal is something obvious like self-preservation, we may not need an explanation. But even in cases where the goal might seem obvious (fabulous wealth, for example), we probably do need to understand the character's motives.
After all, most of us would probably like to be wealthy or at least comfortable, but where do we draw the line on what we might do to reach that goal? Work 80 hours a week? Work at a job we hate? Break the law? Kill someone? And then there's the question of what wealth means to a given character. Is it the ability to buy lots of jewelry, or a dream house, or pay off medical bills? The ability to never have to worry about where the next meal is coming from? The ability to have political power? In other words, does the character equate wealth with safety, or power, or revenge, or attention, or love?
For every external goal a character has, there is often an underlying psychological motive. The more deeply rooted that motive is, the more we are likely to care about the character's quest, no matter what it is.