Logic 101 – Marijuana

My logic 101 post got way more attention than I expected. Now I’m feeling a little pressure, but that’s probably a good thing. It will keep me from getting lazy. Since one of the commentors mentioned marijuana, that’s where I’ll start.
There are three types of argument that I consistently see and hear regarding legalizing marijuana.  The most common, as far as I can tell, is comparing marijuana with alcohol.  There are variations, but the basic argument runs like this:
P1. Alcohol is much worse that marijuana.
P2. Alcohol is legal.
Therefore
C. Marijuana should be legal.
There are two main problems with this argument.  The first is that the premises don’t lead to the conclusion.  You can just as easily read the premises and decide that alcohol should be made illegal.  There has to be a part of the argument that says that alcohol should be legal, and that is missing.  The second problem, is that it is a bad analogy.  Alcohol and marijuana do share some features.  However, those features are not really pertinent to their legality.  Alcohol has been an important part of our society for millennia in a way that marijuana is not.  Alcohol is present in our religious services, at our meals, at our celebrations, at our funerals, etc.  In our culture, marijuana is a recreational drug and that’s really about it.  Banning alcohol would be tantamount to asking people to change their entire way of life (whether or not that would be a good change is beside the point).  Marijuana just cannot be made legal on those grounds.
The second argument is usually stated something like this, “It’s natural, man.  It grows in the ground.”  That’s not really an argument, but applying the principle of charity, I think it goes something like this:
P1. Marijuana is natural.
P2. Natural things are good.
P3. Good things should not be illegal.
Therefore
C. Marijuana should not be illegal.
This is a perfectly valid argument, and therefore true if you accept the premises.  However, if you accept the premises, especially P2, you will run into a lot of problems.  There are many natural things that are not, in fact, good.  Small pox is natural, but you would have a hard time convincing anyone that they should try it.  There is a fairly convincing school of thought that says that rape, murder and war are natural, but that hardly makes them good.  So, the fact that marijuana is natural has no bearing on whether it should be legal.  If you want to use a variation on this argument, you need additional steps that show that marijuana is good.
The third common argument is that marijuana doesn’t cause any harm.  Basically, the argument goes like this:
P1. Marijuana does not harm other people.
P2. The government should not get involved in things that do not harm other people.
Therefore
C. The government should not be involved with marijuana.
Just like the second argument, this is a valid argument.  But, again, it is hard to accept the premises.  For P1, I can think of all kinds of ways marijuana can harm other people.  It can be a contributing factor  in car accidents, it can lead to work place accidents, it can lead to child neglect, etc.  I know that it does not necessarily lead to these things, but you cannot just make a statement that it doesn’t hurt anyone when there are plenty of examples of it hurting people.  And P2 also doesn’t stand up.  The government regulates all kinds of things that don’t harm other people.  I cannot just build any old addition on my house, even if I promise that I am not going to sell the house or if I promise that I will remove it before I sell the house.  I cannot drive without a seatbelt.  In many states I cannot ride a motorcycle without a helmet.  These are things that would only harm me, but the government prevents me from doing them.  This is a bit beyond this argument, but it can be argued that, living in a society, nothing can only harm me.  Or, to put it another way, anything that harms me necessarily harms others as well.  If I die in a car wreck, it necessarily burdens my family or the state to dispose of my remains.  If I lose my job because I got high, it necessarily burdens my family or the state because they won’t let me starve to death.
If you were to construct a good argument for legalizing marijuana, I believe that this third argument is the closest.  There are two ways it can be made better.  The first is to use a utilitarian argument and show that while marijuana does cause harm, the goods it provides outweigh those harms.  Or that the harms caused by the laws banning marijuana are greater than the harms of letting people use it (This is probably the way i would go).  I would imagine that this method of arguing is not often used because it requires real research which is time-consuming and expensive.  The second way should focus on the proper place of the state instead of focusing on harm.  How far into a person’s private life should the state’s coercive powers go?  I have not studied it, but I imagine this is not a common way of arguing it because it forces you to look beyond the issue at hand.  To really argue it right, you need a conception of society as a whole that allows for legal marijuana.  The libertarians do this.  Marijuana is not their cause, but it is a beneficiary of their cause.  I would imagine there are other possibilities, I just haven’t seen them