Concrete pad under brick pillar
I want to put two brick pillars at our front entrance with boxwoods. The bricklayer says all I need is to dig down 4" and pour a concrete pad using the soil as the form. Then he will build the pillar on top (about 40" tall, 2' square). My question, is this going to shift during the winters and crumble in a few years? Shouldn't we pour a 2' deep pad. Hope you all have experience with this one as we plan on doing this next week?