Two Distinctions: A Priori/A Posteriori, and Metaphysics/Epistemology

hi I'm professor McCoy and today I want to talk about a couple of distinctions and logic a couple more distinctions so the first one that I want to look at is the distinction between an a priori statements of an office theory or statement before we get into what these mean I want to note something to do with the grammar of these since these are latin phrases up there a priori is one phrase so in your writing if you're going to write about this you would say and a priori proposition or an fusteria worry for example right so the article stays there rape the ah this is not the article this means from so that's it what these mean an opera or a statement is one which is which we know prior to experience experience experience here can mean observation it can mean data Gaborik gathering any kind of empirical method of gathering knowledge or coming to know something office ariari means posterior to or after or deriving from experience again experience here generally this is some kind of empirical observation data gathering that sort of thing so a priori statement is usually something like something that is purely abstract conceptual and logic something office theory or E is usually something we get from data from evidence from observation so for example in how for your a statement is often things like definitions so for example a square has four sides this is aa priori because we don't need to check we don't need to go out and look at a whole bunch of squares and then count the sides on all of them right we know this is true simply based on the definitions based on what the words in the sentence mean whereas this would be to say something like this white board is roughly square in shape this is awkward story because we need to look right we need to check with the world we need to take a look at the the subject of the sentence this whiteboard this particular thing and we need to know what shape it is and so we've got observe we've got to look at okay so it's roughly roughly square technically it's rectangular and even more technically it's a little bit odd because with the corners and such but it's close to square eight we can generally refer to this as square in shape so what does it tell us so first of all propositions like a square has four sides or this whiteboard is roughly square in shape these could be either a priori or on the stereo rate further arguments can be either a priori or hava stereo so for example different car an argument using these raise some propositions we're going to restate them and argument using these we go to something like one a let's switch it to a rectangle to be more accurate so a rectangle has four sides his premise is AA priori we know this just based on our definitions because we know what rectangles are and we know how geometry works and we know what sides are when we're talking about a flat planar shape we know that this is true as to this board is rectangular this premise is office Terry already because we need to go and check we need to look at our data from the world and this is just one instance of data right one data one piece of empirical information namely what shape is this board and then from this we can conclude therefore this board has four sides and we know this is true not because we count them we don't go 1 2 3 4 therefore the board has four sides rather we say we know what shape to the board is we know something about certain kinds of shapes therefore we can logically infer the number of sides from the data given right suppose we either didn't want to count count one by one more plausible in something like an octagon we don't want to go all right I know something is shaped like an octagon how many sides does it have well I don't necessarily want to go at 1 2 3 4 5 6 7 8 knowing that an octagon needs it has eight sides similarly knowing that the board is a rectangle is a rectangle we're knowing that it's rectangular means that it has four sides they don't need to go and count them and it's still this argument as a whole I mean the argument taken as a whole is still office Terry Orion that's because at least one of the premises in the argument is office Terry ory right at least one of these prep premises requires us to go and check with the world and gather some data in this case just one like I like image in one piece of data the shape of the board but it isn't completely prior to experience or completely without any experience of the world or it is completely from pure conceptual rational analysis we need to go look we need to find this piece of data because the argument as a whole relies on this this aqua or e datum from the world that means that the argument has a whole relies on experience and so the argument as a whole is obviously already that's it not all arguments are office theory or E there are some arguments which are entirely off priori we can get conclusions without looking to the world for any data so following our example at rectangle let's switch to a triangle right so premise 1 the angles of a triangle add up to 180 degrees right we know this from geometry we don't need to go and count we don't need to measure the angles of a bunch of different triangles and they here this out based on you know a statistical average we just know this based on how triangles work conceptually speaking based on what it is for support a particular Euclidean planar shape to be a triangle we know that it's angles have to add up to 180 degrees so from this we can conclude that therefore a right triangle with one 60-degree angle has or maybe I should say also has 130 degree angle this is based on simple arithmetic right we don't we only need this one premise we only need the premise of that that ank the angles of a triangle add up to 180 degrees right so this purely mathematical conceptual premise that doesn't have anything to do with particular observations of any triangles in the world we could know that if there is a right triangle so a right triangle meeting one that has an angle that's 90 degrees right so this one is 90 we and so if we have a right triangle and one of the angles is 60 degrees that means we know that the third one the third angle has to be 30 because these add up 280 degrees so if you have the measurement of two of the angles of the triangle you can find the third this is a priori reasoning this entire this entire argument is not based on any particular experience or data or evidence that you gather this is entirely based on the concepts involved what it is for a shape to be a triangle how do we how angles are are represented and then the relationship between those angles okay so generally a priori arguments tell us in general less than office theory or arguments or arguments that have office area elements and this doesn't tell us that any that there is a particular triangle with a 30 degree angle and it doesn't tell us that any particular angle breaks of that one or the angle of some structure in the room it doesn't tell us what the measurement of that is it just tells us how to find out and it tells us that absolute certainty because it's a deductively valid and in this case ii deductively sound argument but an argument with office theory or ii premises an argument that gathers information from the world can then tell us something about the world so for example our our board being a rectangle argument that tells us something true about a particular thing in this case this whiteboard right so the square has if a rectangle has four sides and the board is rectangular which we know that from observation right that's telling us something about this specific particular thing then we know how many sides the board has and that tells us something specific about the world yeah the maybe arguments there maybe a priori arguments the Telus specific things about the world however whether that is possible and what kinds of things that that can tell us is highly controversial and I'm sure I'll talk about it later I guarantee it but for now just know that off stereo arguments tends to tell us more concrete things about particular things in the world okay so that is one distinction we have are there distinction I want to talk about is between two fields of philosophy which translate to different questions we can ask about propositions and these are metaphysics metaphysics and epistemology broadly speaking metaphysics is the the science or the study of what is what actually exists what its nature is what things are like that sort of thing if it's homology is the study of what we know and how we know it so in generally the broad branches of philosophy metaphysics being the study of what kind of things actually exists and what the basis are for the physical sciences what the basis are for the human sciences and that sort of thing if histology is the study of how we come to know things but the distinction I want to draw is it's derived from that which is how is what kind of questions we can ask about any given proposition so we can ask the metaphysical question it is it true or we can ask the epistemological question do we know that it's true and these are incredibly different things that sometimes get conflated especially when we're talking about empirical facts data and for talking especially about honesty really things sometimes we will confuse these sometimes we'll ask or is this proposition true and the answer well we don't have evidence for that we don't have evidence to tell us if it's true or not a lot of times we may derive from that the conclusion well it must not be true or worse that it's neither true nor false because that's clearly not the case if it's a proposition so I mean there so say you have a proposition for instance alien life exists elsewhere in the universe let's assume for purposes of this discussion at least that any kind of alien visitation conspiracy theories are false let's just assume that for now and say no one no human being knows if advanced alien life exists elsewhere in the universe so we can say alien civilization however we want to specify this so it's it is in fact true that the epistemological question our answer to whether alien life exists elsewhere in the universe or if it some logical answer is we don't know where we here stands for any given human being or even all human beings combining our knowledge together we don't know now the metaphysical question has a determined answer there is an answer to the question and that answer is either yes or no this proposition is either true or its false it's not indeterminate it's not both true and false and it's not neither true and false or neither true or false it is one or it's the other and that depends on whether it is in fact the case that alien life exists elsewhere in the universe and we can see this by little thought experiment so suppose suppose life carries on as it does as it is currently and sometime in the mid 22nd century so a 150 years from now we have first contacts with an alien civilization and after after making their acquaintance and and peacefully or non peacefully interacting with them whatever the case may be we discover that they that their civilization has existed for thousands of years just like ours has right so let's say all right we meet in 2150 we meet 2130 their civilization existed since in our years let's call it 1000 BC they have records going back to that part suppose so at this point in in the 21 50s human beings will know that the aaliyan life is existed for 30-something hundred years at least or advanced alien life is existent for that long so given all of this information supposing all of this winds up being true or roughly true maybe the dates wrong who knows suppose this is roughly true we can answer the question whether in 2017 there is advanced alien life elsewhere in the universe and if all of this is true if we find this out in like 150 years if we find out that this is always been the case it is the case today that there is advanced alien life elsewhere in the universe even if no human being knows it right so this shows us that even if the epistemological question the question of can we know that there is advanced alien life elsewhere in the universe right even if we cannot know something to do with the speed of light right there outside of our light cone and we can't find out until 2150 even if it is it is conceptually impossible for us to know now it is still the case that this proposition has truth value so based on the facts of the matter it hypothetically based propositions true so we're gonna be here what can we do what can we draw from this we can say that regardless of what we know of something that any proposition any statement that could be true or false has to be either true or false not both and not neither for another example something else just to make sure this is clear Euclid's theorem Euclid's theorem as a mathematical mathematical principle that states that there's an infinite number of primes and Euclid in roughly 300 BC held this to be true he thought this was a true proposition however he couldn't prove it with the mathematics that he had it took until the 18th century mathematician in Euler they have proof for this and showed that it had to be true based on the based on the laws of arithmetic so Euclid didn't didn't know this given the mathematical principles that he had even the mathematical tools that he had it was impossible for him to prove that it was true and so we can't prove it however we wouldn't want to say that this principle was indeterminate we don't want to say Euclid's theorem was neither true nor false until the 18th century we want to say that you know that Euler discovered that it was true in the 18th century but that it was true all along so this was true in the 4th century BC when you was writing just as true as it is today even if he had no way of proving that it's true or not this is why in philosophy we generally don't define a fact as something that can be demonstrated as true right we don't say that a fact is something demonstrably true we say that a fact is a true proposition so whether something is a fact is on that physical question not an epistemological question because whether something is true that's metaphysics that's what a fact means right a fact is something that is true the propositions and connectors value and it's true we might learn else or right that we might work we might use it colloquially to say that a fact is something that's democracy demonstrably true something you can demonstrate or prove that is it a bit similan true question that is the question of what can we know not what is these are critically different okay so that's all for this lecture I - keeping these book both of these things in mind will help to clarify lots of months of very difficult philosophical issues or at least apparently difficult philosophical issues that otherwise we may we may be we may get the conclusions right because we can reason through things okay but we may not understand the implications if we don't understand the differences here we may not understand that this being true well okay sure we all agree this is true now regular proof but the implications if this if a fact is only a fact when it's demonstrable the implications might be this became true when you will approve it and that has it's troubling implications like mathematics changing over time and if mathematics is going to be objective it's going to be a fact but how things really work we don't want changing over time similarly we don't want to say that the alien civilization that we meet in the 22nd century we don't want to say they came into being in the 22nd century we want to say they've existed for three thousand years and that we just came to know them when we met them so hopefully that eliminates some confusion and hopefully we can take this away and apply it to some of our other reason till next time

Channel: Professor McCoige

Views: 1,432

Rating: 5 out of 5

Keywords: Philosophy, Logic, A priori, A posteriori, Metaphysics, Epistemology, Critical Thinking, Rationalism, Empiricism, Theology, Big questions

Id: v5X8ySlxoq4

Length: 26min 7sec (1567 seconds)

Published: Thu Aug 31 2017