The analogical argument is the arthritis of society. It keeps us from going where we should be going, being what we should be being, and living where we should be living. It has brought many discussions to a stand still. The opposition to this argument is now swayed for they know there is something wrong with it, yet there seems no way to argue with what is said. My hope is to show that it is arguable. The argument goes as follows:
Is proposition A wrong (or legal, proper, elegant, ethical, etc.)?
A is like B.
B is wrong (or ...).
.: A is wrong (or ...).
In this form it is not difficult to see how this tactic side-steps logic. When used, though, it is slightly less obvious.
One use I've noted of this style of argument is on the war against marijuana. The argument went as follows: ‘Pot is a drug, it has ruined families, it makes criminals rich, it changes how a person behaves and feels, and all of this goes for cocaine too. Surely you don't endorse the legalization of cocaine.' What must be noted in such situations it that marijuana is NOT cocaine, and the differences have the ‘pot'ential to justify legalization. In fact, in order to make that a truly formal argument, the illegalization of cocaine would have to be argued, then there would be a chance of a solid argument. But in the interest of efficiency, the arguer could simply argue the illegalization of marijuana.
Similarly, a popular defense for the retention of the right to bare arms is that it would lead to a Big Brother scenario, i.e. absolute governmental control. Consider that this is in fact the first step. Society would still have to take a multitude of other steps in order for BB to be at the door. The NRA argues that since society is willing to surrender this right, they will then surrender, surrender until He does come to the door. To rephrase, step A is like step B, step B is wrong, .: step A is wrong.
Step A must be argued as step A in order for logic to be preserved. Mind you analogies are useful in that complex ideas can be made digestible for the ignorant masses. Calling the beginning of universe the Big Bang is a drastic simplification; sophisticated scientists studying it don't assume the cosmic genesis is the same as sticking a pin in a balloon. The name only compares the violent explosion. So although comparisons are useful, in order to be logical the point of contention in either case must be virtually indistinguishable. There can be differences, but they must not be related to that being argued.
But this style of argument is not only used in the arms race, or in the drug war. It is used in the fight over abortion, senior driving tests, voting age, cloning, pornography, etc. Realizing this lack of logic could bring a conclusion to many of these issues.
The analogical argument is a heuristic, a short-cut. Heuristics and logic go together like cats and blenders- the result is fascinating but messy.