You want positive interest for an investment (aka money put to work) and you want to provide disincentives for people who hold cash (aka idle money) which just sits there doing nothing useful.
That makes sense I guess. But under fractional reserve banking, any money that is "idly" sitting in a bank account earning interest will be loaned out by the bank to someone who will put it to good use. Similarly, if I buy an interest bearing corporate bond, the corporation that is paying me interest will put the money to good use. It seems to me that interest is a good mechanism for incentivizing those who have money to make it available to those who need it for some productive purpose.
I posted a stupid question a couple of weeks ago and got some good feedback.
@ChristianKl suggested that I start building a model of hypercapitalism for people to play with. I have the first one ready! It isn't quite to the point where people can start submitting bots to play in the economy, but I think it shows that the idea is worth more thought.
Analysis:
http://www.hypercapital.info/news/2015/4/19/a-published-model-of-hypercapitalism
Runnable Code - fork it and mess around with it:
http://runnable.com/VTBkszswv6lIdEFR/hypercapitalism-sample-economy-for-node-js-and-hello-world
I'd love some more feedback and opinions.
A couple of other things for context:
hypercapital.info - all about hypercapitalism
Overcoming bias about our money
Information Theory and the Economy