There are a couple of sources of evidence you can use:

Inductive evidence:

• Examples
• Statistics
• Analogy (example of a different situation that shows parallels to the one you’re trying to evidence)

Deductive evidence:

• Theories

Evidence from authority:

• Expert opinion
• Expert sources with certain opinions or facts

The above list is pretty much self-explanatory, but a couple of things could use some additional explanation. Why is an example so powerful you might think. The reason is that although a single example is hardly scientific evidence, it nevertheless shows you that your EXplanation does occur in real life. At the same time the example also gives a more descriptive illustration, contrary to for example statistics which are simply dry numbers. So psychologically an example, or more examples, that illustrate your EXplanation can be very powerful. To see examples at work, look at just any business book, or self-help book and see them at work. Every theory, or argument, is always followed by a vivid example of a company or person that became successful by adhering to that theory. It makes the theory more real, more tangible, than if you would just present dry numbers and facts and that is the power of examples.

An analogy is, as described, an example of a different situation that shows parallels to the one you’re trying to evidence. For example, suppose you’re trying to support the argument that decriminalization of cannabis will decrease crime. You’re having trouble finding examples or statistics that support that fact, so you look at parallel cases. One favorite analogy is then the abolishment of the prohibition on alcohol in the USA and the resulting decline in crime it had. It has the same mechanism, or EXplanation, as with cannabis, being that a popular/social accepted substance that is banned leads to a high demand for it in the illegal circuits, resulting in a rise in crime. If it is subsequently decriminalized, then crime will drop as legal alternatives will become more popular. Obviously this parallel has its flaws and this is the danger of an analogy, for the opposition will try to show that the differences make the analogy useless as evidence. But nevertheless if you’re lacking in powerful examples to support your case, because it is a new plan that hasn’t been implemented anywhere for example, then analogies are very useful.

If we look at deductive evidence, theories, than what is meant is that we use the scientific evidencing someone else has done and use it as a short cut to support our argument. The difficulty is that it only works if your audience is familiar with your theory and accepts it, or if you’re able to explain the essence of it in a very short time frame. This is often a problem in debates. One popular line of moral argumentation uses the theory of justice by John Rawls, specifically the concept of the ‘veil of ignorance‘ to support certain fairness arguments. In university debating this concept is often well understood by the jury, but outside that context it is often hard to explain given limited time. So although useful, use this type of evidence with care

Evidence from authority can also be useful when needing to support arguments, because you use the reputation and work done by that person, without having to go into detail. Again this saves valuable time. Crucial here is that the authority is accepted by your audience as an authority and that the expert opinion is based on some kind of scientific research, or life long experience. Using a famous movie star as evidence, might work for commercials, but hardly ever for debates. Also make sure your authority is accepted as unbiased by your audience.

Next post will delve deeper into how to present your evidence and whether it makes sense to lie about your evidence.

The advice is thus, know your audience. More specifically know their belief system. A belief system is the network of interrelated beliefs that a person has that collectively makes sense of how that person beliefs the world is. In philosophical terms, a belief is a statement of how the world “is”. In an ideal case these interrelated beliefs support each other, but often not all of them do. If you know a person’s belief system, then you can appeal to those beliefs and immediately have much of their belief system helping you subconsciously to support your argument.

Take an easy example. Suppose you are talking to a socialist public about progressive income tax systems. If you then argue that a progressive tax system is fair, then your audience will subconsciously add their whole conceptual framework of fairness to your argument, without you having to. If on the other hand your trying to convince hard-core republicans that a progressive tax system is fair, then you will need to upset their entire belief system, which will be hard work.

What to do then if you’re faced with an audience that doesn’t support your line of reasoning at first hand. In that case you try to appeal to another belief in their belief system and show them how that belief actually supports your argument. In this way you use the fact that almost no belief systems people have fully justify each other. But make no mistake, this will still be very difficult, because people will try to keep their belief system intact. This will require you considering their emotions and Ego as well, but that is where Pathos comes in. At least from a Logos point of view, this will give you a fighting chance.

Suppose you are trying desperately to sell your progressive tax system to your republican audience. In order to do that you need to appeal to some belief that they hold. For example, that hard work should be rewarded. If you can then establish that although the market assigns value to work in an optimal way, this nonetheless results in some hard work not being fully rewarded, then you have your foot in the door so to speak. It’s still going to be very difficult, but again at least you have a fighting chance.

So the recipy for being able to use the right reasoning to support your arguments is making sure you know your audience well. But what if you don’t know your audience, or your audience is very mixed, what type of reasons do you then use? In that case the 17th century philosopher John Locke gives some advice. He argues that there are 4 generic types of acceptable reasons one can give with the first being most convincing and the last being the least convincing:

1. Natural (Scientific) laws: e.g. gravity
2. Common knowledge: e.g. pyramids are from Egypt, dinosaurs roamed the earth
3. Generally accepted beliefs: e.g. torturing innocent children is bad, genocide is bad
4. Personal experience: e.g. it’s becoming increasingly unsafe in the streets

Now we have to see this through the eyes of someone from the 17th century who still believed that the natural siences provide us with objective irrefutable certainty. Although the natural laws have become less credible then they once were, its still a pretty safe bet people will accept those as valid reasons, with the obvious exception of evolutionairy arguments in certain religious circles.

As we move down the list chances become less that your audience will accept them. However, if those reasons DO appeal to your audience’s belief system, then they can be as powerful as natural laws. An audience filled with UFO spotters (personal experience), will often accept the existence of alien life on our planet over natural laws. The same goes for an audience filled with victims of violent crimes. Good luck convincing them that statistics show violent crime is down.

Nevertheless this list does give you some handle on the type of reasons you can use and their ‘objective’ force in a debate. Scientific laws are more ‘objective’ than personal experience and thus more likely to be accepted by your audience. But in the end knowing your audience and appealing to their belief system is more powerful.

Logic postulates certain certain reasoning structures, that when all supporting premises are true, the conclusion must invariably be true as well. A classic example is:

Conclusion: “Aristoteles is mortal”
Premise: “Aristotle is a man”
Premise: “All men are mortal”

As will be clear a conclusion can be translated into the S from our SEXI model, while a premise is an EX. In logical formulation, using our SEXI model it writes:

S: A = C
EX 1: A = B
EX 2: All B = C

It’s easy to see that when EX 1 and EX 2 are both true, then S must necessarily be true as well. This check on whether an argument is logical is important. For example take the following reasoning:

S: “It has rained”
EX 1: “The streets are wet”
EX 2: “When it rains the streets get wet”

Although this reasoning makes sense, it is logically invalid for the reason that other causes could have led to the streets being wet. Looking at the logical formulation shows where it goes wrong:

S: A
EX 1: B
EX 2: A => B (the arrow reads as ” then”)

As this shows you can conclude from the fact that it has rained that the streets must be wet, but not the other way round.

There are many theories and schemata’s that can tell you whether an argument is valid. It’s a bit too much to deal with in a simple blog, but it does show you the importance of EX. EX not only provides the reasoning behind your conclusion, but also provides the logical validation of your argument.

Why then do we need to have I when we already have a logically conclusive argument. The answer is that logic only determines that a conclusion must be true if the explanation is true. It doesn’t say anything about the validity of the explanation itself. In theory every EX can become its own S which then needs tovbe explained by its own EX. This can go on ad infinitum becoming ever more difficult to prove and at the same time more absurd as you go deeper. This is the stuff philosphers love to do and especially sceptics, as they will point out that at some point you cannot prove anything anymore.

However, from a practical point of view we do not need to go so deep. Assuming we all accept a general basis for accepting evidence, we can shortcut this endless string of reasoning by providing some empirical evidence. This is called inductive reasoning, compared to the deductive reasoning used above. By providing some empirical evidence on top of an explantion, be provide evidence that our explantion is not only logical, but also true. Together, as we have seen above, true and logically sound explanations must lead to a true conclusion.

That in short is some background on the logical basis of the SEXI model. Next we will look at what kinds of evidence can be used and how this logical expose can help you refute arguments of your opponent.

There are good arguments, bad arguments and arguments that aren’t arguments at all. To begin with the last category, often people will state an opinion thinking this to be an argument. For example in a debate about abortion, someone can say: “I believe abortion to be immoral” and think they are giving an argument. What they are in fact giving is a statement, or an opinion. What then makes an argument an argument? An argument is a statement that is supported by some sort of justification as to why the statement is true or valid. In the simplest form this justification takes the form of an answer to the question “why?”. So when someone gives the argument that abortion is immoral, instead of just a statement, then they have to answer the implicit question why abortion is immoral. Such an argument can look like this: Abortion is immoral as it constitutes the murder of a living being. Whether or not you agree with this argument is besides the point. The point is that this is the start of a proper argumentation, instead of merely stating an opinion.

Recipe for a solid argument

What then makes for a solid argument? Well a solid argument needs to be SEXI, which stands for:

• S: State
• EX: Explain
• I: Illustrate (Evidence)

State is the conclusion of your argument, it is that which the rest of the ingredients of the argument try to prove. Ideally, the statement is short, clear and unambiguous. The reason it needs to be short is that you will need all of your available time proving your statement and thus do not want to waste that on explaining the point you’re trying to make. Second the statement needs to be clear. Your audience needs to know exactly what your argument is. Don’t leave them guessing, therefore as a rule you mention the statement/conclusion of your argument first. Don’t bother with a separate introduction, that will be both too long and will have a big risk of making it unclear where you want to go to, or what you are trying to prove. Lastly make sure all the words in your statement are unambiguous. Make sure the terms used are clear, but also make sure the statement itself is clear. For example, is Abortion immoral or not? And if it is only immoral in certain circumstances, make those circumstances explicit from the outset. Don’t keep your audience guessing, they might misinterpret what you are trying to prove. Try to keep your statement limited to one sentence only.

Explain is, as the term suggests, the explanation why your statement/conclusion is true. This is also called your reasoning, some people call it analysis. In terms of formal logic this is where you set out the premises that necessarily lead to your statement/conclusion. The main tip here would be to be as thorough as possible given the context of your speech. Most often people skimp on this part, while it is arguably the most important part. This is the logic/reasoning supporting your argument and this should be robust, well thought through and most of all logical. The biggest mistake people make is presuming the audience already knows all the reasoning supporting the statement. They often don’t resulting in you making intellectual leaps that your audience simply cannot follow. I will go deeper into this part in my next post, but for now remember that your explanation needs to be logically valid and robust.

The last part is illustrates and that is the evidence supporting your argument or reasoning. The reason this is called ‘illustrate’ is that when speeching the use of an example supporting your argument is often the most efficient and powerful evidence that you can use. Nevertheless there are all sorts of evidence you can use to support your argument and every good argument should have some sort of evidence backing up your logical reasoning. Given that you normally have limited time, there are limits to the depth of evidencing you can give (the same goes for explaining), you need to be efficient in this. Use examples, statistics or for example analogies to quickly support your point. You are not supposed to explain the methodology behind the evidence, nor do you need to be fully scientific about it. It needs to be specific and detailed enough that people can check up on it if they so wish. Being able to check your evidence is what will make your evidence convincing instead of something you just made up. I will go further into evidencing in a future post.

Together these three ingredients will make a solid argument. This is a much used structure for argumentation and one that has proven its effectiveness. Just look at business literature or political magazines. They all use this structure. Take the example of business literature. For example they will state that by focusing on shareholder value a company will improve long term profitability. They then explain this by setting out their theory. For example that by focusing on shareholder value management is forced to focus on the bottom line, which will lead them to focus more on profitable endeavors and cost cutting, which in term drive profitability of the company. They then often end with an example of several companies that have implemented this shareholder value and were able to outperform their peers. A clear example of a SEXI argument.

Before I go into the means of persuasion it is important to distinguish between types of persuasion. In the Dutch language both are called “overtuigen”, but the English language makes a difference between to persuade and to convince. The main difference is that convincing is aimed more at showing you are right at the expense of someone else, who has to be wrong, as it comes from the Latin meaning ‘to conquer’, while persuasion comes from the Latin meaning ‘to seduce’. In other words, when persuading someone, you are ‘seducing’ that person to your standpoint using much more softer methods. This way of getting people to agree with you is often used in 1 on 1 discussions, advertisements, sales and of course seduction itself. Convincing on the other hand is aimed at showing your position is stronger that the other’s position, often using harder methods. This type is often used in debates, US court cases and 1 on 1 discussion, though the latter will often be much more heated.

In general, ‘convincing’ is more effective when trying to convince a third party to choose your position over an opponent’s, while ‘persuasion’ is more effective when directly trying to persuade someone of your position. If you try to convince someone in a direct discussion, then you try to do so showing the other is ‘wrong’, which is often not effective as they will try to defend their ego and put up an emotional blockage. On the other hand when you persuade someone, you seduce them to your position, which does not lead to a loss in the other’s eyes. On the other hand if you try to seduce your audience, while being attacked by your opponent, you are far less effective, when you don’t actively defend your position against his of her attacks.

In the end context determines which mode is most effective, but both methods use the same tools of persuasion, they just apply them differently. I will use the terms persuasion and convincing here interchangeably as the tools are the same, but keep in mind the subtle difference between the two in terms of application.

Means of persuasion

According to Aristoteles there are three main methods of persuasion:

• Ethos
• Pathos
• Logos

Ethos is convincing people by means of establishing your credibility as an objective expert, or as someone with a reputable character. Convincing with Ethos is done by gaining acceptance of the audience, gaining their trust and establishing your credibility. Gaining acceptance is best explained by creating some kind of rapport with your audience, or in other words making them like you in a way that will lead them to accept your message more than that of your opponent. Gaining their trust is all about ensuring people will accept you as an expert, or someone who’s opinion counts as an opinion that is worthy listening to and worthy of consideration. Lastly establishing credibility has as a goal to ensure that your audience believes your message and more importantly believes that you are objective and not likely of misleading them for your own purpose. The reason being that people are often unable to fully check the facts of your message.

Pathos is persuading people by means of appealing to their emotions, fears, desires and by presenting your case in an appealing and convincing way. Persuading by means of pathos is all about ensuring a connection with the audience and ensuring the message is more attractive than your opponent’s. This starts by presenting your case in an appealing way, which means making sure you appeal to all the senses of your audience including their emotions. No one wants to hear a boring listing of arguments and facts instead people like stories, anecdotes, visualizations, heartfelt appeals, etc. This will not only lead audiences to accepting your message more, but will also make your message easier to remember. Charisma as a speaker and being able to speak with passion about a subject also helps in this respect. Lastly you need to appeal to the audience’s fears, desires and needs. This will ensure you get their attention, as it makes a message instantly relevant and important. If you can show your position will fulfill their desires and take away their fears than will want your position to be true as it will make their lives better.

Logos is convincing people by means of using argument, reasoning and evidence in order to support your position. You convince people with logos by making clear logical argument, that are supported by solid evidence. The arguments themselves are organized in your speech in a clear and structured way. The most boring of the three, but nevertheless the most important of the three. Without logos, yo have no content and without content your speech will be vacuous. No murderer will be sentenced without some form of evidence, no-one will be follow you merely on your reputation. That reputation needs to be baked up with knowledge, arguments and smart reasoning. Much literature provides evidence that in the end logos is not very important in convincing people, showing facts that non-verbal communication (pathos) is more important than verbal communication for example. This is true, but doesn’t make logos any less important. You should look logos as a hygiene requirement for persuasion. You need to have it, or in other words you should have done your homework. This doesn’t mean people want to hear everything you know, but it does mean that when challenged on it, you need to be able to respond effectively and show evidence where this is needed.

In the end the most effective way of persuasion uses all three methods in unison putting emphasis on one over the other based on the context. In an academic context, Logos will be more important, while when giving a rallying speech, Pathos is much more important. I will delve deeper into each of these three in following articles.

Debating is a formalised discussion with the purpose of convincing a third party by means of arguments.

Convincing a third part: In debating, in contrast to discussing, it is not the goal to convince one another. Only very rarely will one witness a debater acknowledging that the other person is right. Instead, the debaters try to convince a third party that their arguments are better than the arguments of their opponents. This third party can be: the voter, the audience, coalition parties, or in the case of competitive debating, a jury. Take the example of presidential debates in the US. You will never see a candidate acknowledging that the other candidate has the better arguments. Instead the focus their efforts on convincing the voter. Not each other, for they know that it’s pointless

Formalised: A debate is simply a discussion with rules. These rules always include the amount of time a debater has, what is permissible during the debate and rules concerning interruptions. The rules concerning what is permissible concerning simple etiquette, but also regulate the kind of arguments allowed. For example, personal attacks are almost never allowed, nor discriminatory or sexist remarks. Regarding interruptions: in some cases interruptions are not allowed, sometimes the debater has to give permission and in other cases the chair of the debate has to give permission.

In competitive debating the rules also include what the roles of each debater is in the debate. For instance, the first speaker on a proposition side is supposed to outline a case. If he or she doesn’t perform this elemental duty, then the debate will be very messy indeed. Also the last speakers on each side, are almost always obliged to give a summary of the debate. Competitive debating also has rules on what is considered fair in a debate. These rules include the permissibility rules outlined above, but also regulate what kind of cases are fair and, for example, that new arguments are not allowed in the summary.

Types of debates:

There are roughly three generic types of debates:

1. “House of commons”: these debates have a comparable set-up as the debates in the British ‘House of commons’, but different rules. In these debates two groups face each other like in parliament. Two versions then exist. In the first version, popularized on dutch television, every debater is allowed to choose his own position on a subject. In the second version the two groups represent teams, which have to defend a certain side of an issue. In both cases debaters may make a point by standing up and waiting until the debate-moderator gives the ‘the word’. They are then allowed to give one argument, ask one question, or make a single remark.
2. Parliamentary debating: these debates have rules based on the rules governing debates in the British ‘House of commons’, but have a very different set-up. Three versions of this style exist. In American parliamentary two teams of two people each have to defend a side of an issue. The proposing team is aptly called ‘the government’ and the opposing team is called ‘the opposition’. In Australian parliamentary style, two teams consisting of three persons have to defend a certain side of an issue. The last style, which is also the style which is used during the World and European championships is British Parliamentary style. In British parliamentary style, four teams consisting of two people compete against each other. Two of the teams have to defend an issue and two teams have to oppose. The two teams on one side have to work together, but at the same time, have to outperform each other. This resembles the often difficult situation that coalition parties are in. In all versions of parliamentary debating debaters speak for a pre determined amount of time. Often between 4 and 8 minutes each. During these speeches, it is allowed to give interruptions. This is done by standing up and asking the speaker for permission. If the speaker allows it, then the interruptor is allowed to give one point, or ask one question. The speaker is not forced to accept interruptions, but in general has to allow at least 1 or 2.
3. Cross examination: in these debates two debaters interact directly with each other for a pre determined amount of time. During this time debaters may freely interrupt each other. Etiquette often determines that the debaters have to let each other speak, but often debaters try speak as much as possible. It is the most dynamic, but also the most messy style of debating. Only rarely is it done in its pure form. More often it is used in combination with one of the other types of debating. This style is used competitively in the US and is also popular on television.