Weak Analogy?

We should beat children to not do that mistake again because when a thief gets beaten he doesn't steal things after beating, therefore we should beat children to not make these mistakes.

It's an opinion (we should normalise corporal punishment) backed up by a questionable claim ("when a thief gets beaten, they stop stealing").

Firstly - this is not necessarily true. A thief may steal out of necessity (because they are hungry), for money (stealing goods to sell), or for pleasure. In any case, thieves do not intend to get caught, so it is possible that the threat of being beaten will not be enough to deter the act - especially if they are desperate enough to turn to stealing in the first place. 

However, let's assume beating someone is a deterrent. Does that follow we should beat them? In the context of an argument, you could say this is jumping to conclusions because there are other important considerations - such as the morality of inflicting physical pain upon someone for a wrongdoing (either in terms of proportionality, or the act itself), the need for the infliction of such pain (do we have to beat our children, or is there any other way of handling them?) and other ethical considerations.

You think it might be a weak analogy because children are not like thieves (presumed to be adults in this case), and the 'mistakes' that children make are not comparable to theft, for instance, which is another somewhat defensible take, though I think the above concepts are more relevant.

Week Analogy. Opinion. An assumption. I would ask the person to prove it.