Apologies in advance, I've rewritten this post three times now trying to shorten it. Sadly, each attempt has caused it to grow by at least a paragraph. Just be thankful that I cut out the detour through the historic origins of debt and money.
Bitcoin and ripple are both attempts to make new electronic systems that more closely approach the abstract ideal of "money", but they do so in totally different ways.
Certain things have properties that make them more or less useful as money, but in the abstract sense, money is a means of splitting a barter transaction into two parts that can happen at different times, in different places, and between different people.
Essentially, if you buy a product or service from someone, you are getting wealth from them, and in return you give them money, which is (again, in the abstract sense) an IOU for wealth of similar value in the future. They can then take that IOU and give it to someone else in exchange for a product or service. In effect, they are performing a barter where they exchange one thing of value for another thing of value, with the money just as an intermediate step. In the time that they are holding the money, they have given, but not yet received; they are owed a debt, not by one particular person, but by society in general.
Ripple is an attempt to transfer this abstract debt relationship into the electronic world, making something closer to the abstract ideal of "money" than the ledger and paper/coin system we use now. The ripple system just helps turn your personal IOU that you give as payment into a general IOU, which is the same job that money does in a transaction. In the end, both systems require a functional society willing and able to pay back those IOUs, and both systems can be open ended and (more or less) eternal.
All money, including bitcoin, ripple, dollars and even gold, are based on debt. Holding gold means (more or less) that you have done something worth that gold's value, and you hope that in the future you'll be able to exchange that gold for something of similar value. Dollars and ripple are the same, with a couple of subtle differences. In dollars, certain players can create new debt (new dollars) at will, limited only by the willingness of people to accept them. When you get a bank loan (or a credit card or whatever) that bank has created new dollars out of thin air by magic, limited only by their assessment of your ability to repay. In ripple, everyone is a bank, and everyone can create money through magic, just by finding someone willing to accept it.
Gold and bitcoin, though based on debt/hope just dollars and ripple, have the advantage that no one can conjure them at will. Gold and bitcoin are both past-looking, where holding gold or bitcoin is prima facie evidence that a party has already in the past done something of value for society. Dollars and ripple are more forward looking, where one party has received something of value, and the other party is hoping that they will do something of similar value in the future to redeem that particular debt.
The forward looking version of money didn't grow up by accident. It is a good system, and it works. It has produced the amazing world we all live in today. But it has also brought us horrifying tragedy, with new horrors brewing on the not-so-distant horizon. I think that we are perched on a turning point in world history. We will pick either the advantages and disadvantages of future-oriented systems like dollars and ripple, or we will pick the advantages and disadvantages of past-oriented systems like gold and bitcoin. It isn't a one-sided choice, we are both gaining and losing either way.
But I suspect that the brewing storm will steer the next few centuries towards bitcoin (or something like it).
Very well said, kjj. I agree with most of the points you make. However, instead of past-looking and forward looking time vector of monetary systems, I prefer to use trust and distrust based money. If you have gold, silver, or bitcoin you have the ultimate proof that you have already done something useful in the past. This is why there is no need for trust/hope since you already have the proof in place. While money based on debt, like current fiat and ripple, they are based entirely on trust/hope that you will do something useful in future.
The problem with trust based money is that very often this trust is abused. Very complicated systems are used to backup such a trust with something material like real estate. Very often the price of the collateral is changing and needs to be marked to market, inflicting further changes to the reasonable level of trust.
Distrust based money is almost perfect, but almost... The problem is that they are just too expensive to maintain and use every day. They are relatively expensive to trust based monetary systems in a normal economy.
I don't think we are on the verge of making a choice between trust or distrust based money. This is a simple question of efficiency! Economy doesn't care about principles but efficiency. A well balanced monetary system will make use of both trust and distrust based money and will be based on a dynamic trade off. For every day use people will use trust based money since they are cheaper to use and from time to time outstanding credit balances will have to be cleared through distrust based money like gold, silver, or bitcoin that are firmly anchored in the real or digital world.