That's an empirical question, and deserves an empirical treatment. I cannot do that in a comment. Luckily, this question has been thoroughly investigated for almost two centuries. If you want a serious treatment, you might look to:

http://www.jstor.org/stable/825483?seq=2 http://heinonline.org/HOL/Page?handle=hein.journals/uclr52&d...

But if you want a more casual treatment that explains it (and all the associated issues like why bonds and stocks and debt contracts even exist), I really recommend The Ascent of Money by Niall Ferguson.