All the time I hear some public figure saying that if we ban or allow X, then logically we have to ban or allow Y, even though there are obvious practical reasons for X and obvious practical reasons against Y.

No, we don’t.

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79 Responses to Logic

  1. Cloudswrest says:

    A more logical argument is, If you allow them to ban X, it makes it easier for them, and/or more likely, to ban Y in the future, since Y is now an unprincipled exception.

    • gcochran9 says:

      If you let one foot-in-the-door argument push you into doing something stupid, you’ll end up with completely nutty national polices in jig time.

    • The Z Blog says:

      Proportionalism is part of the prevailing orthodoxy so if there can be a case made for an exception, then an exception is made. Race is the most obvious example. We carved out massive exceptions to the principle of free association based on the argument that racial equity was more important. Freedom of speech is going through a similar treatment. Within the next decade, fines for being mean will be common here.

  2. wolf says:

    conservatives frequently used the slippery slope argument during the debate about gay marriage.

    • Sandington says:

      Completely failing to realise that they were already at the bottom of it.

    • Garr says:

      We’ve obviously been sliding down very slippery feminist, homosexualist, and NAMist slopes for at least a century, and the slopes seem to get steeper toward the bottom.

      • Frank says:

        And (in your opinion) what real problems have arisen from those slippery slopes? I’m actually just curious.

        • Gabriel M says:

          Ummm, the last great outbreak of plague in the western world.

          But apart from that, I guess it’s pretty subjective.

          • Frank says:

            Not a very convincing argument. I don’t think feminism had a whole lot to do with that one.

            HIV doesn’t really kill that many people in “The Western World” anymore, and I don’t think many drug manufacturers or their stock holders will be complaining anytime soon.

            Also, scientific funding would be pretty low without cancer and HIV hiding around every corner.

            • AppSocRes says:

              Would you use the same argument for the spread of other MDR STDs such as syphilis and gonorrhea, which seem to have incubated and become endemic within homoisexual populations?

            • So you moved the goalposts when a real example threw your premise to the ground. Then you changed the subject to whether there were some benefits to some people because of the research into solving the “plague.” So at minimum, you actually weren’t “just curious” after all, were you? I have seem that ruse enough times on the internet to officially add it to my list, in honor of you. When someone says they are “just curious,” they aren’t.

              • Frank says:


                I was just curious, and thought there might actually be a reasonable response.

                Instead, the response given prompted me to make a new comment. What’s wrong with that?

                I bet your list is super awesome.

            • Difference maker says:

              That’s a lot of money spent on AIDS

              Also ugly and middling girls are more insufferable than ever. My sympathies to regular joes

              And wasted life on school curricula

            • Gabriel M says:

              This really cuts to the nub of the issue. Sure, doing liberal stuff like legalising homosexuality leads to outbreaks of plague, but we’re already super rich so we just fix it. No biggy. Similarly, thanks to massive advances in crime-fighting technology we don’t need to worry that large swathes of the more, emm, diverse members of urban areas are sub-civilized because they can’t touch us.

              This graph really says it all.

              Long term, the trend is clearly for things to get better. Big advances for liberalism make things worse, but in a few decades that gets wiped out by the long term trend.

    • Ursiform says:

      Like the argument that if we let guys marry other guys we’ll end up with guys marrying sheep? Because you clearly can’t have one without the other?

    • gregor says:

      Not really.

      Conservatives said marriage was about procreation, and the liberals countered that because some couples are infertile yet not prevented from marrying that we must therefore allow categorically infertile gays to marry. THAT is actually more the style of argumentation I think Greg is referring to. We do X therefore we must do Y for consistency. This is a normative statement. Slippery slope is a little different. It says if Y happens then Z will be more likely (prediction, not a normative statement). It’s actually the natural counter to if we do X, then we must do Y. It merely notes that the logic that demands Y also demands Z. The conservatives weren’t calling for Z, merely using that as a secondary reason to oppose the jump to Y.

  3. Franky says:

    Sometimes obvious practical reasons are not so obvious to everyone.

    We need to do X because Arg1.
    Arg1’s logic also applies to Y, but we don’t do Y. So either it must be the case that we also need do Y, or Arg1 is not sufficient to justify doing X.

    • Thos. says:

      Or: there’s a counter-argument against doing Y that doesn’t apply to doing X.

      If X and Y are different, then an argument for one (even if it happens to be applicable because of their similarity) isn’t always going to be SUFFICIENT for the other (because — at the risk of belaboring what should be obvious — they are different).

      It should not need a dictionary to make clear that “similar” does not mean “the same.”

  4. Maciano says:

    I’m all for banning Salafism and all things associated with it. Make these people feel as unwelcome as they are. And, yes, I also think we should be more accomodating to Christianity (& Judaism), because they’re “ours”.

    Universalism & tolerance seem to guide us into policies that will end up making life unnecessary difficult for decent people and unnecessary soft for the worst elements in our society.

  5. AppSocRes says:

    Professor Cochrane: I may be wrong but I think you are describing “slipperry slope” arguments. Please feel free to delete this comment if I am incorrect.

    Offhand, I can think of at least four “slippery slopes” in US politics over the last 75 years or so. These have all led from actions that seemed benign but whose current consequences would probably appall the original decision makers.

    (1) The “slope” that led from Griswold v. Connecticut in 1965 through Solomon v Texas through Lawrence v. Texas in 2003, to the current situation.

    (2) The “slope” that led from early feminist rhetoric and laws against sex-based discrimination in the late 1950s and early 1960s up through to the present where: (a) Title IX has given federal bureaucrats near absolute control over college and university policies regarding athletic programs, campus disciplinary procedures, and other matters and (b) there’s a push for female participation in all military activities including combat and special forces ground opertations.

    (3) The “slope” that led from Roe v. Wade in 1973 to the present where abortion on demand seems to have become a constitutional right. The documented intent of the Justice’s handing down this decision seems to have been two-fold: (a) to grant some limited right to an abortion and (b) via this means remove from the table further political divisions resulting from debates over the legality of abortion!

    (4) The “slope” that led from the Voting Rights Act of 1965 to serious erosions of the rights to free association and free expression in the present.

    One may argue about whether these “slopes” will ultimately prove to be descents into social dysfunction and disaster or ascents to a better society but the “slopes” themselves are real. The persons setting into motion the original changes would most likely not have done so had they seen the outcome. That the frog has not yet boiled to death is not firm evidence that he never will.

      • Space Ghost says:

        Responses like this are why I keep coming back to this blog.

      • AppSocRes says:

        Please delete me then. But would you provide some further explication of your point. I’m not being snarky. I really would like clarification or an example of what you are thinking about.

        • et.cetera says:

          Think about various arguments used for/against the legalisation of various drugs. E.g. “how come marijuana is illegal but tobacco isn’t.”

          • AppSocRes says:

            Believe it or not, I’ve been working on and off in the area of substance use, abuse and treatment policy at various levels from federal to state and local for the last twenty five years. Perhaps I failed to see what was right under my nose. But quite honestly, my perception is that an equally good case can be made for not banning any intoxicating substances or banning them all; for no restrictions or for absolute prohibition. Insurmountable problems first seem to arise when incrementalism is introduced. The end of Prohibition saw a vast increase in alcohol abuse and dependence and the deaths associated with these conditions. Attempts at removing restrictions on marijuana use are already causing serious problems in states that have taken this route. Unfortunately my black-white-equally-acceptable position on these issues is heresy and not something I’d advocate for in any official role, even though I could defend it given sufficient space.

            • Frank says:

              Unfortunately, you can ban all the drugs, but people will still use them.

              Unless your country is a little island and you watch over everyone all the time.

              • Ursiform says:

                You’d have to watch over them very carefully. There is a big drug problem on California’s death row, which is supposed to be pretty secure.

              • TWS says:

                That’s due to visits or staff. You can control for drug smuggling if you control the quality of the staff and who and how you allow access during visits.

            • Jim says:

              I believe that there is evidence that Prohibition decreased accident rates and work absences. About 50% of accidental deaths are alcohol related. I don’t know if anybody has done a careful economic study of the benefits vs. costs of Prohibition.

              • Mark F. says:

                Well, it may have decreased consumption — at least for a while. But crime went way up during the 1920s. But be careful about correlation proving causation.

  6. The Z Blog says:

    One of the many reasons I have a dim view of libertarians is they prefer to deal in absolutes. Banning the sale of heroin has a different set of trade offs than banning alcohol. Public policy should be about debating those trade offs, but that’s rarely the case anymore.

    • another fred says:

      Most people, especially those who feel passionate about something, argue from the extremes. It is as though they refuse to acknowledge that trade-offs exist.

      Thoughtful people know there is a balance between protecting the individual and maintaining social order (and that said order protects and benefits individuals).

      The chaotic pendulum swings as the varying costs of disorder increases relative to the cost of repression.

      • albatross says:

        I think partly this reflects the difference between being an advocate for one side and trying to actually find a sensible policy. The advocates have little incentive to talk about trade offs or messy inconvenient details to their preferred policy. That’s true whether you’re talking about legalizing drugs or invading Iraq or eliminating the minimum wage or tightening immigration enforcement.

        So if you’re really trying to decide whether we should legalize drugs, you need to think about how many additional addicts we will have, or what happens when the next crack shows up; if you’re just advocating for it, you’ll probably avoid those issues.

        FWIW, I support legalizing most drugs, but there is no way that’s a costless, painless policy.

    • Mark F. says:

      But surely you believe in some absolutes. Should we be debating the trade offs in allowing slavery? As for heroin: Is it really as bad as people think? People just seem to assume it is somehow the worst drug ever. You know, like people used to assume homosexuals were evil perverts and destroyers of civilization who should be persecuted. What are the facts?

      • another fred says:

        “Should we be debating the trade offs in allowing slavery?”

        In the days before there were government “safety nets” people often placed themselves in bondage to get shelter and food. Were they wrong? Will it be wrong if the “safety nets” unravel?

      • The Z Blog says:

        I suspect your post is mostly virtue signally, but why would you not want to debate the trade offs slavery? If you really think slavery is bad, then you would embrace a factual argument over the trade offs of slavery.

        And yes, heroin is bad, but I suspect you are a libertarian, which means none of this makes any sense to you.

      • dearieme says:

        I know almost nothing about heroin, which is – to put it mildly – a black mark for those who warn against it, because it means that over the decades they have told me virtually nothing factual about it.

        • Thos. says:

          Because there is no source of information you could access on your own? Or, because it is their job to make sure you are educated?

        • Garr says:

          Everything I know about it comes from Velvet Underground and Rolling Stones songs. Except for brief chats with four former users and a student’s casual assertion after class that he’d done it in the bathroom during break.

  7. cloudswrest says:

    Often the target really is “Y”, but the proponents can’t get there in one step, and the opponents are too stupid to not surrender “X”.

  8. Political arguments are inherently illogical and until the Cochrans’ of this world out number the dumbshits’ of this world that is the way it is going to stay. You will hurt your brain trying to reason with a political ideologue because they love the world to be just as simple as their thinking. We think we have the worst candidates saying the worst things ever about each other. We need to read history to keep things in perspective. Thomas Jefferson versus John Adams was the birth of negative campaigning and perhaps has never been lower since. Jefferson had hatchet men label Adams “a hideous hermaphroditical character” and challenged Adams to drop his pants and prove he had just male private parts. Adams said Jefferson was the son of squaw whore and a mulatto father. Of course the slander continued until they finally hit upon the truth. Jefferson had to deny that he had a black mistress, Sally Hemmings, and that they had children together for the rest of his life.

  9. IC says:

    slippery slope fallacy

    • Garr says:

      It may be a logical fallacy, but it’s certainly not a psychological or sociological fallacy. We slide down slippery slopes frequently in our private lives (e.g. collapse of a marriage), and societies obviously slide down slippery slopes (e.g. feminism).

  10. Philip Neal says:

    Note also the phrase “the logic of X”: for instance “the logic of open borders”, “the logic of European integration”, “the logic of the single currency”, “the logic of harmonisation”. It is a particular favourite of EU federalists and serves to create the impression that some development is inevitable when it is not.

  11. Schrodinger says:

    For example, X country is a country of immigrants => every kind of immigration is baking X country better.

  12. EugineNier@gmail.com says:

    You may want to read this by Yvain that covers various ways slippery slopes do in fact happen.

  13. I may be missing the point, but there are contexts where slippery-slope arguments make sense. This is something that people in game theory, like Thomas Schelling, have written about.

    The argument doesn’t make sense if A (the other player) and I share the same objective function, if we agree on what’s best for the community, or just for the two of us. Then we can just agree that (say) allowing X and banning Y is fine.

    But suppose we have different objectives. I want to allow a lot of things, including X and Y, and A wants to forbid a lot of things, including X and Y. The status quo has been that X and Y are off the table, and A has been adamant about keeping it that way. A throws a temper tantrum and starts talking about sacred values and threatening the nuclear option when there’s any talk of changing things. But now A starts to waver. Maybe A would be willing to allow X after all. But Y? NEVER! OVER MY DEAD BODY! However, after making a concession on X, A’s commitment to keeping Y banned is less credible. If A isn’t willing to take a stand on X (however silly X may seem), then A may be vulnerable to salami tactics, where any one piece of salami is not worth fighting over, so A ends up losing the whole thing.

    Human relations (territorial disputes between nations, public policy disputes between Left and Right, relations between men and women) are full of situations like this. Even people who haven’t studied game theory often have an intuitive sense that X may be worth fighting over for this reason, even if making concessions on X would entail little cost, or even some benefit.

    Of course part of negotiating is framing: trying to convince A that she’s being irrational in making a slippery slope argument (“It’s called the slippery slope FALLACY for a reason. You can Google it. Would I lie to you?”), and that once I get my way on X, I would never, ever dream of asking for Y as well.

    Schelling’s book, The Strategy of Conflict:


  14. dearieme says:

    The “slippery slope fallacy” seems to me to be a propaganda name. The “slippery slope” is not a point of logic, it is an allusion to common human behaviour in a social setting.

  15. RCB says:

    Didn’t your English teacher ever tell you to be concrete?

  16. Investors Anonymous says:

    What’s your opinion on Elon Musk’s ventures?

  17. Are you sniping at Curtis Yarvin again, Greg?

  18. st says:

    I think Greg meant “we do X because of Z; now, Z is no more so we do not have to do anything, but instead of doing nothing, we do Y or advocate doing Y since we already did X anyway.” Which is wrong.

  19. Henk says:

    In order to enforce a ban on X but not on Y, you must be able to distinguish X from Y followed by differential enforcement on X but not on Y.

    If this is physically or legally impossible, while an indiscriminate ban on both is physically and legally possible, the logic holds.

    If you allow marriage for heterosexual pairs you logically must allow marriage for homosexual pairs because you can’t legally discriminate based on sexual orientation. Your constitution has been found to be implicitly very specific about this.

    • gcochran9 says:

      I’m sure that Madison would be surprised.

      • Jim says:

        Yes, I don’t know of any evidence that any of the founding fathers ever even thought of the issue of homosexual marriage. The idea that they intended to forbid discrimination based on sexual orientation is preposterous.

        • Fourth doorman of the apocalypse says:

          Indeed. They may well have considered the idea of homosexual marriage so preposterous that it did not merit a mention in the constitution.

        • Henk says:

          I had to look up the following names because admittedly it’s not a list I’ve committed to memory. So… Roberts, Kennedy, Thomas, Ginsburg, Breyer, Alito, Sotomayor, Kagan.

          Madison? Who is Madison?

          With zero names on the list, dead white men seem underrepresented relative to their share in combined past and present populations. That sounds kind of deeply unfair!

          On the other hand, maybe we’ve stumbled upon a phenomenon that needs a name. Say, “the history buff’s trap”. That’s when history comes alive for you so vividly and convincingly, you forget the dead really do have some trouble fighting for your cause.

  20. Fourth doorman of the apocalypse says:

    Since we allow male circumcision, what grounds can we have for not allowing that other form, in all its variants?

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