hi I'm dr. Johnson Hoss and welcome to earth parts a logical fallacy is a mistake in a logical argument it is where the logic is broken in some way someone has done an end run around logic and has jumped to a conclusion and logical fallacies basically describe specific ways in which that can happen particular ways that are that are uniquely recognizable as repeated mistakes that people make in bad arguments a lot of these have Latin names and if you took a logic class you would get an exhaustive treatment of this and I can't do that here but I'm gonna introduce a few that tend to crop up a lot when discussing science specifically something like climate science or the history of life on Earth or any other form of science that becomes culturally controversial you'll see these a lot and you'll see these a lot in advertisements in political ads in politics in all walks of life really so let's start with a common enough one there applies to many forms of environmental science and in medicine the naturalistic fallacy this assumes that anything that occurs naturally is safe if it's natural if it's all-natural that means it's safe whereas conversely everything produced through technology or through manipulation of science is somehow dangerous or morally suspect or even inferior to the natural version and there are instances where natural may be better and synthetic may be better but the general fallacy is to assume that natural is always better and one wonders does does that include if you wanted to say I prefer to use only natural products because they are healthier if you say that do you really apply that also to things like the heavy metal mercury arsenic cyanide what about cobra venom botulinum toxin there are lots of things in nature that are very very dangerous and are deadly nature is full of hazards just because it's natural doesn't mean it's good for you conversely just because it's technological doesn't mean there's anything wrong with it for years now there's been an ongoing contra see over genetically-modified foods where one side claims that this is completely safe and is the next wave of technology to save the world the other side says no this is all cancer-causing frankenfood in reality the people who've looked at this have come to the conclusions over and over again that in fact there's not really anything apparently wrong with genetically modified food they works it's not dangerous it doesn't hurt anyone but the ideology that natural is better has prevented in some cases developing nations from accepting donations of food because it's genetically modified grain where they would prefer people to starve than to be fed things that were designed partially in a laboratory and that's sad because there's no real evidence that any part of genetically modified food is in any way harmful at all so the naturalistic fallacy can cost lives the laws of physics and chemistry are not different for things that humans build versus things that occurred naturally the argument from Authority I've touched on this already elsewhere in this lecture but this is essentially basing an argument on some authority figure instead of the evidence instead of the actual evidence supporting or not supporting the argument it's assigning sources as more important than what the source says ancient texts people who individually we might revere as cultural heroes these all might be things that have value but can't really be treated as authorities where it's the be-all end-all if you said for example Isaac Newton didn't believe in evolution you think you're smarter than Newton no it's just that Newton lived before the evolution was discovered and Newton was a human being am i smarter than Newton no but he was a person he was a human being he contributed for example a lot to science but he also believed in alchemy because people did then it was a thing it doesn't mean anything else that he discovered that can be verified as true is untrue because of that it's because it was right and it worked it doesn't have to do with the person you can't say you don't like evolutionary theory because of Darwin any more than you can I don't like nuclear power plants because I don't like Madame Curie there's just no connection there the ancient scrolls of truth tell us the moon is hollow trust the scrolls that would be an argument from Authority because it's saying the scrolls tell us everything we need to know well I look further and if the scroll says it the scroll must be right well no it doesn't Scrolls are written by people people can be wrong and ancient peoples believed all sorts of things most of which is mutually irreconcilable with each other and with the real world as we know it now authority is not something to trust expertise is a different thing where a person is telling you how they came to their conclusion and showing you the steps and saying here you want to take a course in it I'm offering it next fall an authority is someone who proclaims on high this is truth and you must obey me and proclamations like that rarely have any value to any sentient person a curious opposite form of the argument from Authority has emerged in the Internet era and bears mentioning I don't know what you call it officially but let's just call the argument from lack of authority the idea that your lack of expertise makes you independent or a maverick outsider and therefore your ideas should be cherished and the ideas of stuff the establishment types should be ignored this is a social argument based upon discomfort with people who know things that you don't the fallacy here is arguing that the lack of expertise in a subject is compelling evidence that I am correct about that subject this is an obvious fallacy when people say things like what we need in Washington are more regular Joe's like you and me my response would be no I would prefer people in Washington to be qualified and experienced experts in public policy and effective methods of maintaining a civilization I think it's valuable to have people who know what they're doing just like the heart surgeon analogy if there's a new opening for a heart surgeon at the nearby top-rated Hospital what's your choice for the person to fill that job one of several world-class cardiac surgeons who've applied for the job with their vast credentials and experience and some of them have invented new techniques or do you want the car mechanic who's a really good car mechanic probably one of the best in the state but has never even taken a biology class but he is a maverick outsider he's not part of the stuffy establishment thinking is he so should he be the one that we hire to be head of cardiac surgery at this hospital I don't think so and I think that logic should be applied fairly to every other arena of life appeal to ignorance this is a common one that doesn't mean as harsh a thing as it sounds like ignorant says become a word that we culturally use to insult but taken literally is a as it's taken here as it's supposed to be taken ignorant simply is you're ignorant of a topic you're ignorant of a certain thing I am ignorant of how to speak most languages on earth I am completely ignorant of how to put a car together from scratch I don't know anything about stamp collecting there's a lot of things that I'm completely ignorant about simply because life doesn't give you time to become an expert in everything and you just have to acknowledge that so in this case appeal to ignorance means basing an argument on the absence of information about something it just means I don't have any information about something but I really want one answer to be true so I'm gonna substitute that answer in with a lack of evidence I can jump in and take the place of evidence with my preferred explanation I can say because we don't know what that light in the sky is it's obviously gonna be a UFO so it must be a machine from another star system it's I don't know what it is therefore I know what it is unknown equals unknowable in some ways this fallacy overlaps with appeal to ignorance it's unknown means it can't be known it assumes that because we don't understand something right now that thing cannot be understood human consciousness is far too mysterious to be ever explained by science say we who have not done it yet just like lightning infectious diseases earthquakes and fire eventually we figure it out you just got to be patient there are people working on this stuff part of being a scientist or thinking scientifically is in fact being willing to say I don't know and I'm going to suspend judgment until better information comes in I can't say that something is true because no one has disproven it I can't substitute my preferred explanation and when there's no evidence particularly supporting it I also can't say that because something is unknown no one will ever figure it out this is sometimes called the God of the gaps argument the idea that wherever there's a gap in our understanding it either either has a magical explanation or it cannot be explained and history has shown that when people put their minds to it and are careful in thorough and serious we can discover a lot the ad hominem argument this is the only one that I'll use where I'll start off using the Latin version first ad hominem means to the man literally it basically means that you're attacking the advocate of an argument instead of the argument itself you're not attacking the meat of the argument what flaws there might be in it you're not taking those apart you're saying that because of some aspect of the person presenting the argument the argument is wrong you might say I don't believe in climate change because Al Gore's a jerk maybe Al Gore talks funny well that may be your personal opinion of a human being individual mammal but it doesn't really address the question of whether or not a particular scientific issue is valid or invalid the person is not the argument a version of this is sometimes called poisoning the well where you try to portray a person themselves as being somehow repugnant or they represent an out-group in society or are somehow suspect because of their associations and therefore whatever that person says you hope becomes untrustworthy if you're making this argument poisoning the well is a form of an ad hominem argument and frankly a lot of political ads are ad hominem arguments I don't even have to use any specifics but whenever you see a political ad that attacks a person and not policy then you're basically seeing a kind of end run around the real argument related to the ad hominem argument is the straw man are and they can overlap sometimes these aren't quite as separate and distinct as we'd like them to be because life is messy but a strawman argument is essentially making up a caricature of your opponent or the opponent's argument and attacking that caricature instead of addressing the actual argument making a character caricature that people will laugh at or will think ridiculous you might say for example look climate change can't be real I just went outside into snowing that's a straw man argument nothing in meteorology or climate science even remotely suggests that anthropogenic climate change will banish winter from the earth that's just a straw man that's a caricature meant to seem ridiculous and then when you laugh at it you are looked at it is look I'm laughing at this stupid idea look how right I am a straw man argument deliberately creates a mistaken or warped caricature of something that is easier to attack then the the actual thing if people say evolution can't work because it's just random you can't just randomly have life happen from nothing well that's not what evolutionary theory says the role of randomness and natural selection is randomness might generate new mutations mistakes in copying but those mutations have very non-random effects they have very deterministic effects on the outcome of that individual the source might be a mistake but the effect is very real evolution has nothing to do with randomness making life that is a straw man argument based upon a flawed understanding at best of how it really works appeal to popularity it's trying to argue that because something is popular it must be true that the weight of public opinion can alter the fabric of reality if you say for example most Americans don't believe in global warming so it must be a hoax or simply untrue the fallacy here is that that's not how real life operates you don't conduct science by vote we don't vote on what the acceleration due to gravity is we measure it popular beliefs are rarely based on evidence they're based upon culture tradition history whatever fads whether something is popular enough has absolutely nothing to do with whether it is true it either is true or it is not and the number of people that support the idea really has no bearing whatsoever on its validity now you might have trouble with this in the light of the concept of scientific consensus because often people are told that they should trust the scientific consensus the scientific consensus on climate change the scientific consensus on whatever this is not the same as voting and it's very important that I make that distinction it's not that scientists all go into a secret room and put on strange robes and are told what to think and to tell the masses and that's the scientific consensus or that they vote on it that everybody is working on some aspect or angle to that problem if they all start pointing in the same direction that's a consensus if most people who are working on things that connect to a problem are all looking the same way and coming up with basically the same kind of result and that is a consensus it is an independently arrived at separate convergence of the opinion of experts on that topic a scientific consensus emerged on whether tobacco can cause lung cancer after years of work where it wasn't just a study showing nicotine effect cells in a petri dish and causes cancer it's not about mice given tobacco smoke it's about everything epidemiological studies population studies tracking people over time lab work on mice yeah lab work on extracted organs basic biochemistry a long long list of research and all of that work independently was converging on the answer that tobacco can cause lung cancer and so that's where the consensus emerged it wasn't voted upon you might think about in this situation what might occur to you is when Pluto stopped being a planet you might say well wait people scientists voted on that yeah they did the International Astronomical Union got together in a room at a conference and they voted on whether Pluto should still remain a planet or be considered Worf planet or a minor planet something like that but here's the thing they weren't voting on changing Pluto they're voting on what to call it they're voting upon what set of rules do you use to apply the term planet to a thing there was no one arguing that we should decide that the diameter of Pluto was some different value than it really is everyone there accepts the reality of what Pluto is physically it's just what do you decide as a common scientific language we apply a word to it that was a vote a consensus in science is talking about an actual scientific problem where we don't know the answer and we're trying to find out you