Actually, the question you should ask is 'where is your witness?' - the lender needs to have more than documentary proof of your debt.
Here's how the process plays out:
When you owe a debt what happens is the lender will contact you a few times and then, if you don't pay, they will sell the debt on to people who are in the collections business. And over the course of a year or two your debt will likely change hands multiple times, at incredible devaluation. (Listen to the This American Life episode, it's great in this regard.)
These companies will make all sorts of outlandish claims about what might happen if you don't pay. In reality, nothing at all will happen outside of the hit your credit rating will take if they take the issue that far. All things considered, that's a non-issue for most people facing debts they have no way of repaying.
In the not very likely event you are actually summoned to court, what will happen is that the lawyers working for the current owner of your debt will try to strong-arm you before you go before a judge. They'll say 'let's settle this now before things get serious in there' etc., and will offer to accept a fraction of what the paper says you owe.
That's when you ask, 'where is your witness?'. The chances of the 2nd or 3rd collection agency to purchase your packaged debt being able to haul into court the very same loan officer who witnessed you sign for a loan years ago approaches zero for cases involving less than seven figure sums.
Source: advice given to me by a debt counselor during my own business loan default 'issue'.
Update: the idea of bad debt ruining your credit score is a myth. I defaulted on a high-five-figure debt and two years later qualified for a six-figure mortgage with a mid-five-figure income. Most of the talk of 'this will go down on your permanent record' is FUD.