Q&A: Does knowing Good really make you good?

Plato and his teacher Socrates had the theory that a person who knows what good is, will always do good and never do evil.  At first the thought seems highly illogical for men such as these two foundations of Western philosophy.  Think about a situation where a single parent is struggling to feed his\her kids.  To help fill their stomachs, the parent steals bread from a local bakery.  Stealing is an evil thing to do, but nearly anyone wouldn't want the kids to starve, so is satisfying the kids' huger negate the evil act of thievery?  From my point of view I feel that is 'good' to steal under the circumstances.  I haven't a clue has to what kind of answer Plato might have.