Pot Logic: Affirming the Consequent

Canada is debating the decriminalization of the personal possession of small amounts of marijuana. I heard a representative of a police association on the CBC the other day make an argument that I recognized from my Practical Logic philosophy course.

Unfortunately, I don’t have a link to the original quote, but the argument was roughly this: 100% of heroin addicts in Canada started with marijuana. The implied premise here is this: therefore, smoking pot leads to heroin use.

This is called affirming the consequent. If A then B. B therefore, A. It’s wrong. All leprechauns drink Guinness. You drink Guinness, therefore you are a leprechaun.

I know this isn’t a new argument, in fact, it’s quite obvious. That’s exactly why I thought it was notable. It was so obviously a logical fallacy that I was amazed that it was stated so simply.

Perhaps we should be teaching the basics of arguments and fallacies in grade school.


18 thoughts on “Pot Logic: Affirming the Consequent

  1. I don’t agree with the report done for the house at all. The report says having 30 grams or less should not be me a criminal act.

    I don’t know about you guys, but i consider 30 grams of pot to be a lot. It’s between $450 – $500 worth of pot in street value, thats trafficking if you ask me.

    Having 3 grams or less on your person is nothing big and there for you should not be charged and have a record for your entire life.

    On another note, could any of you picture Binns being high? 😛

  2. This CBC News Sunday did an amusing demontration of how much 30 grams is. They rolled about 130 joints with 30 grams of Oregano.

    However, what really got me about this argument has nothing to do with drugs at all – it was the blatant use of a logical fallacy that fascinated me.

  3. Ah, Philosophy 101, Practical Logic.

    Andrew, I’m curious: you want it to be legal to carry around small ammounts of pot. But you think it should be illegal for a person to sell you this pot? I’ve never quite understood this end of the argument.

  4. Another good one I heard on CBC was from a police officer here in BC. He claimed that a high percentage of young kids have sampled pot, therefore, do we really want our children showing up stoned at school every morning if it’s decriminalized?

    Hmmm… Alcohol isn’t illegal, and lots of young kids have sampled it… do we want them showing up loaded at school every morning. How about Portugal or Switzerland where pot has been decriminalized? All those kids stoned at school!

  5. What kills me watching all these 35-45 year old cops is the idea that the widespread teen use of the demon weed is new. I clearly remember watching during high school late 70’s the doors of vans in the parking lot opening in plumes of smoke when the bell rang for the end of lunch. There is no doubt the same incredible amount of weed in the jacket pockets of teens now as there was 20 and 30 years ago. That is a fact that will not change no matter what the law says. The loonie thing is that 660,000 Canadians have criminal records for simple possession. Criminalizing 2 percent of the population [knowing that likely more than another 10% did not get caught] is just stupid and wasteful.

    3 grams?! Put it in corner stores and maybe 3 grams.

  6. Nick, legal is not the same as decriminalized. Underage drinking is illegal, but getting caught does not give you a criminal record. However if you were producing and selling alcohol you would end up with a criminal record.

  7. Newfie Premier Roger Grimes made the best and strongest point this past week: legalize it, regulate it and sell it through the Liquor Commission. That way, it can be sold at a reasonable approximation of market price, an age requirement can be enforced and tax dollars can go to hospitals rather than the local arsehole who profits now on selling to teens.

  8. I’m actually happy with the current laws in place… I have never owned my own little stash a pot. I have tried it, but it was always my friends who gave me a little to try. I however, don’t think it is fair that some one who has a very small amount can get stuck with a life record that could lead to them not getting certain jobs, or even losing the one they currently hold.

  9. Defiantly a very sensitive topic… I think every one has a view toward what should be done. Most Government members who agree with making it legal will never come forward with fear of being beaten up and ripped apart by the opposition.

  10. That’s why Mr. Binns stands so tall in the pantheon of great leaders of Canada…”I experimented”, he admitted last week…and where? “University.” Where do you think paddy boy got the perma-grin? Been locked on since those glory days of university experimentation. When things are bad and folks are giving him a heavy time, he can always fall into a reverie of recollection, the beads, the fringed leather jacket and his little science ZigZag wrapped projects…

  11. I wonder what percentage of of people not addicted to heroin smoked marijuana.

    I think the biggest hurdle for decriminalization in Canada is protest from the United States. They fear that easy access here will make drug traffic from Canada a huge problem for them. They would have to decriminalize too, and we all know that isn’t going to happen any time soon.

  12. Steven, you’ve oversimplified the original statement and then created a false analogy.

    Using the terms of your analogy, the policeman actually said, “All leprechauns became leprechauns after drinking Guinness.” The implication being that if we remove Guinness from the world, perhaps people will stop turning into leprechauns.

    He didn’t say that all pot users become herion users, just that all herion users started as pot users. A Venn diagram of this argument would be a large circle (pot users) with a smaller circle or herion users inside of it.

    If it is indeed true that 100% of herion users started with pot, then it is possible that increasing pot use will also increase herion use. And it’s possible that it won’t. I don’t think there’s ever been a controlled study to discover if pot use is truly a causal factor in the future use of other drugs.

    There’s plenty of anecdotal and circumstantial evidence that pot is a gateway drug, and this is what the anti-legalization arguements are typically based around.

  13. There are many other factors which are “gate-ways” to criminal activities which are not themselves criminalized: poverty, poor education, a heavy metal 1970’s record collection. Use of criminalization of a somewhat benign and popular activity to stop another activity which not popular and not benign is a dangerous and resource wasting activity. Beer would also be a “gate-way” as might be applying for unemployment insurance. In each instance a Venn diagram might be created but would the fact of the dependency of the crime on the somewhat beneign and popular activity be established? Consider a much more dangerous crime than herione use – drunk driving by adults. Adult access to alcohol is definitely a critical factor upon which the crime is based but one which is little regulated let alone criminalized. There is much more the boogieman and belief than good lawmaking and science at play in the resistence to change.

  14. Two logic posts in a row. Hmm, someone’s feeling mentally superior these days…

    and here in the US, we have three-time pot users serving life sentences, displacing first-time murders in our prisons (who then get paroled after five years). Three strikes and we’re screwed. We could use decriminalization, too. Hell, our President was a cocaine user for g*d’s sake.

  15. i don’t actually believe the majority of police officers are against legalisation. Most of the law enforcement officers that I’ve spoken with on the subject (an admittedly small sampling of half a dozen or so) don’t believe these offences should be considered a crime. I think the lack of support for the current proposed changes in the legislation comes from the police organizations and unions.
    The trouble with decriminalizing is the paperwork. All of a sudden the cop on the street is called upon to make a judgement call as to whether some one is trafficking or just using. I can’t imagine any officer wanted to have more “grey areas” so far as enforcing the law goes. That’s why we’ve got to legalise it! Common sense is losing out to the wild imaginings of worse-case scenarists… and bureaucrats who know how much work this would take.
    I’m so dissappointed with Pat Binns, who admits being a pot-“experimenter”, supporting the continued criminalization of that behavior. I’m also finding it hard to believe that we, as a generation of “pot-aware” people haven’t taken this opportunity to rise up and say… “Pat, dude, come on! i mean you know what i’m saying?”

  16. Dave has it right. Lets speak to Pat in the language of the boomers! He should talk to Roger in Newfoundland about full legalization and relax…relaaaax. It’ll all be spliffy if they just put on a little Grateful Dead, get out the old tie dye tees and think about the tourism opportunities. Hell, half of Vermont will move here for the summers once a little Maui wowwie pops up next to the mickies in the LC. Wow man…that would be greeaat…got any chips?

  17. `Come, we shall have some fun now!’ thought Alice. `I’m glad they’ve begun asking riddles.–I believe I can guess that,’ she added aloud.

    `Do you mean that you think you can find out the answer to it?’ said the March Hare.

    `Exactly so,’ said Alice.

    `Then you should say what you mean,’ the March Hare went on.

    ‘I do,’ Alice hastily replied; `at least–at least I mean what I say–that’s the same thing, you know.’

    `Not the same thing a bit!’ said the Hatter. `You might just as well say that “I see what I eat” is the same thing as “I eat what I see”!’

    `You might just as well say,’ added the March Hare, `that “I like what I get” is the same thing as “I get what I like”!’

    `You might just as well say,’ added the Dormouse, who seemed to be talking in his sleep, `that “I breathe when I sleep” is the same thing as “I sleep when I breathe”!’

    `It IS the same thing with you,’ said the Hatter, and here the conversation dropped, and the party sat silent for a minute, while Alice thought over all she could remember about ravens and writing-desks, which wasn’t much.

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