When I was still in college, a friend of mine, Jeff, and I had several conversations about various topics, but he wouldn't let me use analogies to try to make my point. Whenever I tried to draw an analogy between two different things, he would say, "All analogies are by nature false." Of course, as I later learned all statements are by nature analogies. Consequently, my friend's logic, if laid out, would result in the following:
1. The phrase, "all analogies are by nature false," is a statement.
2. All statements are by nature analogies.
3. All analogies are by nature false.
Therefore, the phrase "all analogies are, by nature, false," is false.
Obviously, my friend's claim is self-referentially absurd. In fact, analogies are useful tools to help clarify points in an argument, and a blanket statement such as my friend's are simply means of trying to dismiss a point without considering it.
Now, in fairness to my friend, what he probably meant to say was that "no analogy is an identity." In other words, there are always going to be differences between the two analogs being compared in an analogy, because if they were exactly alike in every respect they would be the same thing, i.e., identical. This same point is made when reviewing the informal logical fallacy of weak analogy from Fallacy Files.org:
Analogies are neither true nor false, instead they come in degrees from near identity to extreme dissimilarity. Here are two important points about analogy:No analogy is perfect, that is, there is always some difference between analogs. Otherwise, they would not be two analogous objects, but only one, and the relation would be one of identity, not analogy.
There is always some similarity between any two objects, no matter how different. For example, Lewis Carroll once posed the following nonsense riddle:How is a raven like a writing desk?
The point of the riddle was that they're not; alike, that is. However, to Carroll's surprise, some of his readers came up with clever solutions to the supposedly unsolvable riddle, for instance:Because Poe wrote on both.
Some arguments from analogy are based on analogies that are so weak that the argument is too weak for the purpose to which it is put. How strong an argument needs to be depends upon the context in which it occurs, and the use that it is intended to serve. Thus, in the absence of other evidence, and as a guide to further research, even a very weak analogical argument may be strong enough. Therefore, while the strength of an argument from analogy depends upon the strength of the analogy in its premisses, it is not solely determined by that strength.
The language used at Fallacy Files makes two things clear about the way in which fallacies must be evaluated. First, look at the context in which the analogy occurs. In other words, what is the purpose of the analogy. What is the main point that the analogy is intended to make or illustrate? Once that purpose or point is identified, then the second step is to see whether the analogy differs in any substantive respect from the analog that would make the intended analogy inapplicable. Simply pointing out differences between the analog and the analogy that don't go to the point of the analogy is nothing more then pointing out that an analogy isn't an identity.
Likewise, when discussing Christiainty or some of the issues related to Christianity, analogies can be helpful tools. The mere fact that an analogy is used that is different in some respect from the analog doesn't mean that the analogy is flawed. The strength or weakness of the analogy depends upon the point that the writer or speaker is seeking to make. In some cases, the analogy fails because it is flawed in the very point of the analogy. In other cases, the analogy may be very different from the analog, but the analogy may still be spot on with the point the writer is seeking to make.
An example of the first is the illustration of the man as an analogy to show the Trinity. In the analogy, the man supposedly is an example of three in one -- he is a son to his father, a father to his son and a husband to his wife. Being father, son and husband yet only one man makes three in one, right? Well, not really. The anlogy fails because the point of the analogy is to show how one thing can be three separate things. In the analogy, the man isn't three separate things. This particular analogy is an example of the heresy of modalism because the man isn't really three things, but merely one thing presenting himself in three modes.
An example of the second is C.S. Lewis' analogy comparing God with the author of a play from Mere Christianity:
Another possible objection is this: Why is God landing in this enemy-occupied world in disguise and starting a sort of secret society to undermine the devil? Why is He not landing in force, invading it? Is it that He is not strong enough? Well, Christians think He is going to land in force. We do not know when. But we can guess why He is delaying. He wants to give us the chance of joining His side freely. I do not suppose you and I would have thought much of a Frenchman who waited until the allies were marching into Germany and then announced he was on our side. God will invade. But I wonder whether people who ask God to interfere openly and directly in our world quite realize what it will be like when He does. When that happens, it is the end of the world. When the author walks onto the stage, the play is over. God is going to invade all right. But what is the good of saying you are on His side then, when you see the whole natural universe, melting away like a dream, and something else, something it never entered your head to conceive comes crashing in. Something so beautiful to some of us and so terrible to others that none of us will have any choice left. For this time it will be God without disguise. Something so overwhelming, that it will strike either irresistible love or irresistible horror into every creature. It will be too late then to choose your side. There is no use saying you could choose to lie down when it is become impossible to stand up. That will not be the time for choosing. It will be the time when we discover which side we really have chosen. Whether we realized it before or not. Now, today, this moment is our chance to choose the right side.
In this case, Lewis is using the comparison for one point only -- to say that when the author comes onto the scene of the play, the play has ended just as when God (who is like the author of our universe) comes into the scene, the universe as we know it will end. Now, all kinds of arguments can be made (and have been made) about how God differs from the author of a play. But these type of arguments are red herrings because Lewis isn't using the analogy to argue that God is like an author in how the universe is created or being played out. He is doing so only to make the point that when Jesus enters the picture, the show is over. It is spot on with respect to that claim.
So, when arguing about the claims of Christianity -- or any claim, really -- when analyzing analogies that we make or that others make it's important to recognize two things: first, the purpose of the analogy, and second, whether the objection being made really impacts the purpose. Don't waste time tearing down points unrelated to the real purpose behind the analogy.