One
is not allowed to put money into a business venture where he shares in
profits but not in losses, or even where his proportionate share of
profits is greater than that of his losses. The guaranteed part of the
investment is then a loan, and the profit on it is a form of interest
prohibited by the Sages.
However, one is allowed to invest the money of orphans where they stand to gain more than to lose, by a court appointee.
One
is allowed to loan on interest to a non-Jew. In fact, there is nothing
wrong with charging interest, but the Torah wants all Jews to behave
like members of a family.
