Example Essay 2

Name: Matthew

Student Number: 00000000000

Wordcount: 938

Passage

One of the longest standing arguments against the use of marijuana is that it gives users a “gateway” to harder or more illicit drug use. Bierson states in his article that “Marijuana is the seed from which the scourge of drug abuse grows. If we stop the marijuana, we will stop the rest of drug abuse”. I have several issues with this statement: first, the simple fact that many heroin and cocaine users used marijuana first does not conclude that the latter is the result of the first. Correlation is not causality. Bierson’s vehement argument against marijuana alone become suspect, as most of these heroin and cocaine abusers had also previously used alcohol and tobacco. According to government surveys, a conservative estimate of 80 million American have tried marijuana in their life, and 20 million admit to using it recently; if marijuana were truly a gateway drug, we would see a higher percentage of regular users. Instead we are seeing an even smaller percentage of abusers of cocaine or heroin. In fact, most people who use marijuana most often quit on their own before the age of 34. If anybody is still compelled to buy into the “gateway” theory, a real-life example is available for all to see: In Holland, marijuana has been partially decriminalized since the 1970’s. Reports show that the use of cocaine and heroin has significantly decreased, thus contradicting the hypothesis of marijuana as a gateway drug. Instead, these statistics appear to point to the conclusion that marijuana is more likely a substitute for harder drugs rather than a launching pad.

ARGUMENT FOR MAIN CONCLUSION 1

Standard Form

P1) Any argument that infers causation between two things solely on the basis of a correlation between those things is a bad argument

P2) Bierson’s argument that marijuana leads to harder drug use is based solely on the correlation between marijuana use and harder drug use

__________

C) Bierson’s argument that marijuana use leads to harder drug use is a bad argument

Argument Map

Assessment of Argument for Main Conclusion 1

The author is rejecting Bierson’s argument against marijuana use because it makes the post hoc fallacy – it infers a causal relationship from the fact that one thing comes before another thing. But this is insufficient to infer a causal relationship. The author’s argument is deductively valid.

I am not confident about P2, though. Confusing correlation with causality is a serious mistake, and not one a serious scientist would make easily. I would like the author to produce some evidence to support P1, and not just assume it as a starting premise. Without this evidence I am not confident the argument is sound, and so the argument is not giving me confidence that the main conclusion is true.

The author may be trying to use his conclusion that Bierson’s argument is unsound to reach the conclusion that marijuana use does not lead to harder drug use. As this argument would be invalid (because we cannot infer the falsity of a conclusion from the unsoundness of an argument for that conclusion), and I am not completely sure the author is reasoning in this way, I have reconstructed this argument as an independent argument.

ARGUMENTS FOR MAIN CONCLUSION 2

Standard Form

Argument 1

P1) If marijuana use leads to harder drug use, then there would be a higher percentage of marijuana users who go on to abuse cocaine or heroin

P2) There is a smaller percentage of marijuana users who go on to abuse cocaine or heroin

__________

C) Marijuana use does not lead to harder drug use

Argument 2

P1) The use of cocaine and heroin in Holland did not increase after marijuana use increased

P2) If marijuana use leads to harder drug use, then an increase in marijuana use would always lead to an increase in the use of cocaine and heroin

___________

C) Marijuana use does not lead to harder drug use

Argument Map

Assessment of Arguments for Main Conclusion 2

The author’s second main conclusion is that marijuana use does not lead to harder drug use. They have two independent arguments for this conclusion.

Argument (1) has a straightforwardly valid deductive structure, but I have problems with P1. Cocaine and heroin are hard drugs, but they are not the only hard drugs. There is morphine, crystal meth, LSD etc. So the antecedent of P1 could be true even if the consequent is false, if, for example, marijuana use causes morphine use but for some reason (availability, expense, the police etc.) does not cause cocaine or heroin use. For this reason, I actually think P1 is false.

Argument (2) is likewise deductive and valid, but I think P2 is false for the same reasons.

I think that the author themselves is unclear throughout the passage about whether they are talking about harder drugs (including LSD, morphine etc.) or just cocaine and heroine. I think that they want to conclude that marijuana use does not lead to any hard drug use, but the data they have is only for cocaine and heroin.

ARGUMENT FOR MAIN CONCLUSION 3

Standard Form

P1) The use of cocaine and heroin in Holland significantly decreased after marijuana use increased

P2) If the use of cocaine and heroin significantly decreases after marijuana use increases, then an increase in marijuana use leads to a decrease in the use of harder drugs

_________

C) Increase in marijuana use leads to a decrease in the use of harder drugs

Argument Map

Assessment of Argument for Main Conclusion 3

This argument is unconvincing because it is making the post hoc fallacy. The decrease in use of harder drugs after the increase in use of marijuana is insufficient to establish a causal relationship. There may be many other possible causes of this – for example, better policing and tougher sentencing for hard drug use could have caused this decrease.

The argument also has the same problem as the arguments for marijuana use not leading to harder drug use – switching between talking about cocaine and heroine use, and talking about harder drugs, as though they meant the same thing.

Conclusion

The author has three main conclusions: Bierson’s argument that marijuana use causes harder drug use is unsound; harder drug use is not caused by marijuana use; marijuana use can lead to a decrease in harder drug use. None of their arguments are convincing and do not give me any confidence in their conclusions.

The author’s rejection of Bierson’s argument on the basis that it makes the post hoc fallacy needs more support, and the author makes the same fallacy himself in arguing that marijuana use leads to a decrease in harder drug use. Furthermore, the rejection of Bierson’s argument does not give any support to the author’s other conclusions.

A persistent problem in the author’s arguments is their desire to draw a conclusion about harder drug use from facts about cocaine and heroin use. They are unable to do so, as the category of harder drugs is much wider than just cocaine and heroin. They should either limit their conclusions to talking about cocaine and heroin, or provide some evidence that cocaine and heroin use makes up the vast majority of harder drug use.