Part of the problem is that the pro-marijuana and anti-marijuana groups are both making decisions based on uneducated opinions (although the anti-marijuana groups are increasingly off-base). With that said, let's put down some very simple ideas:
1) Marijuana funding terrorism, violence, etc. - This is the best reason to legalize and regulate it: take the drug market out of the hands of gangs and violent organizations. In the Middle East in particular, they make a good profit off of hash (which is generally what they're growing the marijuana for), but the violent organizations prefer pushing heroin...better margins.
2) Marijuana being a gate-way to other things - First of all, everything you do is a choice, and you can construct an argument that suggest any variable A is a gateway to variable B. Studies have demonstrated that cigarette smoking is more likely to lead to hard drug use than marijuana smoking is. Further, many legal pills are highly addictive and have much the same effect; the only difference is that they have lobbyists and the money to pay for toxicology reports.
There are two legitimate arguments here: First, research from the John Hopkins Medical University suggested that a possible reason for graduation from marijuana to harder drugs is because a marijuana user loses faith in the drug education they've received once they find out that marijuana is nowhere near what it is made out to be by the DEA. The second argument is that someone who smokes marijuana must buy from a drug dealer, who has a strong incentive to sell the buyer something harder with greater addiction rates and greater profit margins. Once again, taking the drugs out of the dealers hands is the best solution.
3) Marijuana will make you stupid - Again, real scientific research calls this into question. THC has been shown to promote the growth of new neurons. It is also known that short-term memory loss (one of the common concerns of the anti-marijuana groups) is only a problem when the cannabinoid receptors are over-stimulated; in other words, small frequent use is not particularly problematic. Further, cognitive testing from Columbia University demonstrated that accuracy on cognitive tests was not affected by marijuana use.
4) Marijuana damages your lungs - Thorax found that there was no positive association between marijuana smoking and emphysema. The most important part though is that marijuana is not damaging to your lungs when vapourized, according to the journals Clinical Pharmacology & Therapeutics and Journal of Pharmaceutical Sciences.
5) Marijuana will cause lung cancer - The UCLA Medical Center found that there was no association between marijuana smoking and lung cancer; the lead administrator of the testing even suggested that there may be a protective effect from the THC.
6) Driving after smoking marijuana is dangerous - I think driving when unfocused, regardless of the cause, is bad. Still, testing from Britain's Transport Research Laboratory showed that marijuana was less detrimental to reaction times than alcohol or even text messaging.
That is just the tip of the ice-berg. Obviously there are detriments to marijuana, in the same way that there are detriments to eating a 10 oz steak. If you look at the science, you would see that not only is it doubtful that marijuana is harmful enough to warrant being illegal, you'll also see that there are a number of positive reasons that suggest it should be recommended for a variety of conditions (Alzheimer's Disease, for example).
As long as people ignore the science that is done, the argument will continue. Even worse, the US and the DEA have reach into almost every country's drug policy and the result is that the marijuana testing that is required (ie. toxicology, THC profiles, etc.) is nearly impossible to do, and extremely cost-prohibitive. Not only are they preventing marijuana from being used, they are trying to prevent scientists from knowing more about it. That hardly seems like a wise approach to any substance on this planet.
Instead, they choose to lock people up and destroy lives for something they do not even understand. Not only is the approach illogical, it is also damaging to the lives of good people.
Every person in this thread, including those who enjoy marijuana, should make sure they understand the real attributes of this plant and the effect it has on people. Arguments like "You stupid stoner" followed by "You stupid conservative" do nothing to enlighten those who don't follow the political situation closely.
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