A Crash Course in Formal Logic Pt. 1

hello there everybody and welcome to my first ever a crash course in formal logic in this first part of the first series we're going to cover logic arguments and premises and conclusions all explained simply but you have to warn you one thing that won't be simple about this course is it as a crash course we're going to be covering about two lectures worth material in each one of these video presentations so hold on tight for that now in the first course I'm going to cover logic basics that's just basic argument analysis fallacies category logic and propositional logic including truth table and natural deduction methods and that should be enough for any college-level introduction to logic but later on I'll offer an advanced course and logic covering probabilities quantified modal and first-order quantified modal logic now Aristotle's the person we have the credit with first formalizing logic as a discipline and he also created nearly every other discipline that we study in the university is almost from scratch it's been said about Aristotle he may have been the last person on earth who knew everything there was to know in his lifetime now arguments as we're going to study them are not heated exchanges or personal assaults and by the same token they're not merely disagreements and opinions or the automatic contradicting of an opponent or one's opponents position even though the term argument is sometimes used that way in the vernacular now one person who exploits this use or understanding of the term argument is Charles Schultz and his peanuts cartoon series Lucy a Schroeder white likes Beethoven better than her and well shorter comes a little bit argumentative and that sort of argumentation does not leave room for discussion Lucy complains Linus is another person who's always itching for some verbal combat when asked if it's a beautiful day learnin Linus replies with a lot of combative questions and what he says last of all is pretty interesting a good fanatic is always ready for an argument now that may be true but a good fanatic is not ready for an argument in the sense that we are going to define the term this is a logic course and logic is the science of argument evaluation we put arguments under the microscope of logic and see if those arguments stand up or whether they work in order to do that the first thing we're gonna have to do before we study logic is to get an understanding of what an argument is an argument is a set of statements in other words one statement by itself never constitutes an argument then unique thing about these sets of statements is this some of those statements called premises claim to be support or reasons for another in the batch so you get these sorts of relationships of evidential support holding between statements the statements that give evidence are they called the premises and the statements that receive the support from the premises on the opposite end of those arrows those statements are called the conclusion well now that we've defined the term arguments it's time to move on in define statements in more detail statements are sentences capable of being true or false for example if all cats are said to be vicious that statement would be false but notice we have a sentence here capable of taking a truth value and similarly somebody might say that some old men are grumpy in that sentence is more than likely true since we just limited it to some old men but again statements are a unique type of sentence now not every sentence or utterance qualifies as a statement there are certain very meaningful sentences or utterances such as where's my milk yowee or get me a sandwich perfectly meaningful but not statements why well as a general rule questions exclamations imperatives and commands cannot take truth values because they don't assert anything about the way the world is therefore they cannot be true or false and they cannot be statements and they cannot serve as premises or conclusions and arguments as we have defined the term argument well so far I've given you a lot of important terms the most important of which on this little cheat sheet that you can look back on is the term inference that's the reasoning process of an argument it's whatever type of reasoning gets you from the premises or to the conclusion and we'll study that more detail later on for example consider the following batch of statements all film stars are celebrities how the berry is a film star and Halle Berry is a celebrity you can divide these statements up and DePrima C's and a conclusion that can be reached upon them and as it turns out in this case all of our statements turn out is true but that is not always the case consider the following batch of statements how about some film stars or men and Cameron Diaz as a film star therefore Cameron Diaz is a man well if you'd these are premises and conclusions what we find out is that the premises statements turn out true and the conclusion statement turns out to be false the point here is this in this sort of case something seems to have gone wrong with the inference the leap from the premise statements to the conclusion statements and what went right or wrong in these inferences is the subject matter for logic in this course but before we study logic in any detail we got to get more clear on how to distinguish conclusions and premises one helpful hint is indicator words and just about any good logic textbook is going to give you a list something like this therefore accordingly entails that wherefore don't memorize the list just get the basic principle that these are conclusion indicators they tell you that somebody's about to state the conclusion of their argument for example somebody might say tortured prisoners will say anything to relieve their pain and consequently torture is not a reliable method for obtaining information from prisoners now that term consequently tells you that the persons about to state the conclusion that they've reached upon their reasons or premises probably given earlier in conclusion indicators aren't your only helpful tool there are also premise indicators reason indicator terms such as since in that seeing that as indicated by all of those sorts of terms tell you that the person is about to present reasons for a particular point of view that they hold so for example parents should never shake a crying baby why reach that conclusion since the baby's delicate body and brain might be easily traumatized since indicates a reason or a premise statement is about to be given now regarding reasons watch out for this term mcdonald's has fatty foods for this reason I should go to Subway in this sort of paragraph reason indicates that a conclusion I should go to Subway is about to be reached but by way of contrast I should go to Subway for the reason that McDonald's has fatty foods well here reason indicates that a premise is about to be offered so for those of you who might be a little confused let me clear this little matter up when somebody says for this reason this looks back to a reason already given and says that a conclusion is about to be offered on the basis of reasons already given previously however for the reason that looks forward to a reason that is about to be given so that is a premise indicator there are some other helpful tips when you're dealing with the paragraphs and conversations in everyday life one indicator word may signal more than one premise for example since my company's the red and I'm not seeing any hope of recovery I should file for bankruptcy technically speaking you could divide this up into three statements my company's in the red I'm not seeing any hope of recovery the conclusion statement is I should file for bankruptcy two premises or two reasons were given for that conclusion and also sometimes you'll find that there are no indicators in a passage and if that happens suspect the conclusion was offered upfront maybe I've just been playing frog or too much but I came up with this example I shouldn't cross the road it's rush hour and the last two frogs were flattened notice no conclusion and no premise indicators here but the conclusion I shouldn't cross the road receive support from two other statements well as I promised from the outset of this video in each video you can receive about two college-level lectures in logic and this is where I start lecture number two basically we're going to cover the topic of is it an argument because I find that logic students once they get started distinguishing conclusions and premises and making out inferences they tend to find arguments in every conversation or paragraph that they read and that's not the case we need to distinguish between the paragraphs and conversations that contain arguments and those that don't there are two conditions for an argument you have to have a set of statements the premises claiming to present reasons and a claim that there's a conclusion that has been supported two claims now the first claim the factual claim is not something that logic evaluates the truth value of the premises that's just something you have to figure out on your own logic evaluates the support or the inference claim but the point is you have to have two claims on the table to have an argument a factual claim or set thereof without the inference claim amounts to a non argument so to spot arguments and non arguments you have to learn to spot inferences and spot non inferences so we have two lessons to cover here real quickly first spotting inferences inferences can be explicit when they use premise or conclusion indicators that makes things easy since my company's in the red and I'm not seeing any hope of recovery I should file for bankruptcy the premise indicator word there gives away the inference so use those indicator words if you find them in a passage but watch out for them I have a few caveats that I need to add later on otherwise the inference can be implicit for example in the case of the Frog crossing the road the reader had to catch the inference because no indicator words were offered so arguments may lack indicator words and in a second we're going to see a few non arguments that might even have the indicator words the point is this don't use indicator words as a crutch for spotting inferences and such if you think that you have an implicit inference on the table insert and therefore in front of whatever you think the conclusion is if the passage makes sense chances are you are dealing with an argument in the case of the Frog it's rush hour and the last two frogs were flattened therefore I shouldn't cross the road makes perfect sense therefore we can tell the inference was there all along it was just implicit now consider this as Einstein developed his relativity theory he was unknowingly laying the groundwork for quantum theory and since Einstein published his theories quantum theory has enjoyed many successes looks like we have premise indicators indicated in the red right well that would be wrong as and since are not being used here to indicate premises or reasons they are time indicators as means at the same time and since means subsequent to the time consequently there is no inference really being made here and no argument now contrast that with a passage like this since quantum theory was not likely to develop without Einsteins work he deserves some credit for the theory despite the fact that he actually disliked it interesting bit of trivia right well we're being asked to infer here since is being used as a premise indicator and the conclusion here is that Einstein deserves credit for a theory 'but he really didn't like well now let's talk about non inferences specifically four types of non inferences that are commonly mistaken for arguments if you want a more detailed exposition of this I recommend Patrick Hurley's concise introduction to logic but in the meantime I'm going to abbreviate that sort of conversation drastically and just cover the four main areas where students are tempted to make mistakes instruction does not amount to offering of an inference whether the instruction is negative like a warning the u.s. cannot keep running up its deficit without winding up in the same financial catastrophe as Greece or a positive bit of a device if we want to keep the US economically secure we ought to first cut reliance on foreign fuels the temptation on the part of students is to twist these bits of advice and warning into premise by premise arguments like premise the US should not allow itself to wind up like Greece and premise if it runs up its deficit it will wind up so and there's a conclusion that follows and the same sort of thing happens in the case of the positive bit of advice the US should not allow itself to lose Economic Security and Economic Security is best preserved plausibly through less reliance on foreign fuels and a conclusion follows that the US should decrease its reliance now for a lot of students this might be tricky because they're thinking that the Warner or the advisor would certainly like the arguments that we spelled out premise by premise and that surely they were assuming something of this form of reasoning or logic when they offered their warnings and bits of advice but how do you know for example that the advisor thinks that less foreign fuel dependence is the best solution to our economic security problems you've attributing a premise to the arguer that they do really didn't argue and this is a tricky point warnings and advice usually are based on or presupposed some reasons but that does not mean that the advisor offered or stated them so when somebody offers you warnings or bits of advice that doesn't mean that they're offering you an argument per se and a similar point holds with respect to expressing opinions take a look at the Glovers quarrel below you're always nagging me for spending time with my friends and you're just jealous his interlocutor responds no you just don't want to spend time working on the marriage now the temptation is to attribute an argument premise by premise to the arguers in this case your accusations are merely based on jealousy my friends and premise such accusations so based or unfair and conclusion is your accusations are unfair but wait a minute the interlocutor in these cases I shouldn't call them an argue er really didn't offer a premise by premise argument like this did they again just because you think the speaker does should or must hold a set of reasons for what they say or Express does not mean that they have those reasons you're just guessing at that and it certainly doesn't mean they've offered them and that they've offered some sort of argument location point is nearly all political talk whether you get it from the right wing or the left wing what you see in so-called political debates is generally not really anything in the way of argumentation but rather an elaborate spelling out of one's views on a political topic and if you'd like to get some exercise on making the distinction just go to the opinions section of your local newspaper oftentimes you find people doing argumentation and sometimes they're just expressing in an elaborate way their point of view on a particular particular topic so to be able to make the distinction within that sort of section of paper is a very important skill to develop now let's talk about information giving that does not amount to inference offering consider reports it reports just give you information the temptation on the part of students is to see a slant or a gist or to sense that a reporter's driving at a conclusion and then to assume that the reporter has offered an argument for example somebody says sales of assault guns have increased drastically critics of assault rifles say the following and recent school shootings have resulted in well obviously this person seems to have an axe to grind they're presenting a lot of negative information but notice they didn't state a conclusion off the basis of this information and hence they did not offer an argument in our sense of the term expositions are another form of information giving they're just lengthy talks around a topic and if you confuse these four arguments you probably gave in to the temptation to confuse the topic sentence of the talk with the conclusion but that's not the same thing if somebody says eggs benedict is a delightful and impressive dish you can make easily and this is how you poach the eggs and prepare the muffins and here's how to make the sauce they're not arguing you into the position that eggs benedict is a delightful impressive dish they're just giving you a lot of instructions an exposition on exactly how eggs benedict is made and illustrations are expositions that are littered with examples these can be very confusing because the temptation is to confuse an assumption that the speaker makes followed by some examples with a controversial conclusion that is argued for from various instances these are very different cases compare the following suppose somebody says there's many many types of screwdriver including the Phillips head the flat head the hex even the early Robertson's head now this person is not trying to argue you into the position that there are many many types of screwdrivers unless of course you've started the conversation just debating that sort of issue which I doubt that anybody would do it just doesn't seem like a controversial conclusion they're just giving you an at exposition with examples now by we've contrasted a war and peace rally if they said war by itself can never resolve conflicts now that sounds controversial the person may choose then to back up their claim with instances like the civil war bringing decades of division World War one ending with the treaty that brought world war two consequently to cold war turmoil in Korea and Vietnam clearly this person is arguing from the instances and that's a different thing all together from illustrating a topic sentence so bear in mind topic sentences are not conclusions and there's a temptation to confuse topic sentences with conclusions that needs to be resisted there are various connections between ideas that do not amount to offering an inference and this can be confusing because inferences involve some relationship between ideas contained in the premises and ideas contained in the conclusion but there's other ways of connecting ideas that do not involve inference explanations are a very popular one that's where you try to shed light on some sort of event or phenomena and usually you have an explanation hint that's the thing you're dumb about and then you have the exponents which answers why is that thing happening but that doesn't mean that the exponent um and explains constitute conclusions or premises consider a great clap or classic case the case of Sir Isaac Newton who had a certain explanation tides roll in at night he gives the explains there's a gravitational force that holds between the moon and the waters now the temptation on the part of students is sometimes to take the explanation as a conclusion because if there is a gravitational force holding between the moon and the waters it would follow that ocean tides would roll in at night but notice nobody was really confused as to whether ocean tides rolled in at night we didn't know why it was happening but nobody had to be argued into that as a conclusion this was not an argument now explanations are like arguments reason giving activities the exponents gives you a reason why the x-plane anthem is happening even consider this example lucy asks why don't you ever call me cutie now there's an interesting explanation and Schroeder apparently gives her an answer or an exponent that she doesn't like because he doesn't think she's very cute and lucy complains that she hates reasons now explanations do give a reason for the X plane and um that's true but it's not the same relationship as a premise and conclusion relationship now here's a difficulty sometimes if an explanation is good and it covers a lot of ground doesn't that argue for its truth and the answer is yes sometimes but notice something here first of all when that sort of thing happens usually what you have is not an argument for the explanation you have an argument for the explains the answer why because the answer why is so good now when that happens that sometimes called an inference to the best explanation and we'll cover that in the next lesson but the point for now is explanations by themselves do not amount to inferences or arguments in another connection between ideas is just the straight forward if this then that the conditional statement you say if a then B a is said to be sufficient for B and B is necessarily to follow upon a now the temptation on the part of students is to take these conditional statements and treat a as a premise and B as a conclusion is that right well consider this example if I'm taller than Shaq then I'm taller than you isn't that right but what are you going to conclude on the basis of that well I'm not asking you to reach a conclusion it's probably the case that if I'm taller than Shaq I am taller than you but I'm not saying that I'm taller than Shaq and I certainly am not trying to infer that I'm taller than anybody listening to this lecture it's just a connection between two ideas that probably does hold now here we can counter another difficulty that you're going to have to sort through in later lessons conditional sentences are often important parts of arguments you're going to find them as premises very often and we're going to go to detail on that in future lessons however the point for now is that by themselves conditional sentences do not constitute arguments and that's kind of the lesson with respect to explanations and conditionals that can be important parts of arguments but that does not make them arguments in themselves and if you can remember that you won't get tripped up and spa inferences when there really are none well I've given you a whole lot of material for now wait for my exercises on this lesson and as promised you've done in less than 20 minutes to college-level classes in logic so congratulations feel free to review and wait on my next logic lesson thanks again everybody

Channel: PhilHelper

Views: 141,695

Rating: 4.9185982 out of 5

Keywords: arguments, logic, premises, conclusions

Id: ywKZgjpMBUU

Length: 21min 0sec (1260 seconds)

Published: Sun Jun 30 2013

Reddit Comments

[u/mutantvirus]

Louder does not mean "more right"

[u/1thief]

EMSK: Math

[u/NoveltyAccount67]

Eh. Not that necessary. Logic is good because it's precise but it's not particularly good as a method of reasoning. There are also multiple logics and it's not clear that classical logic is the best.

For anyone downvoting, I go into detail an reasons below. You might as well read it. I've studied plenty of logic and plenty of philosophy. Let's talk about this instead of dogmatically defending logic with downvotes.

Edit2: Okay, I guess that not a single one of you will actually defend your viewpoint. It annoys the hell out of me when people who know absolutely nothing about logic or philosophy defend it dogmatically. If you don't know the subject, why be so confident that you're right? Just because logic has such a wonderfully positive connotation?

[u/king_hippo77]

Every Vulcan Should Know: Logic

[u/TequilaMico]

Very interesting stuff. Entertaining too. Good work.

[u/madeyouangry]

EMSK that in order to effectively communicate with a female, he needs to abandon any and all techniques covered in this post, its comment thread and any premises, information and facts relating to logic.

[u/voyaging]

Finally some real logic. Really pisses me off whenever I see that "fallacy" graphic that's actually a bunch of informal fallacies and are basically useless to know.

[u/CloudDrone]

Thanks, OP. I enjoyed this. I haven't studied logic at all, so it made me happy to stumble across this crash course.

[u/[deleted]]

Quality post!