All men are mortal, Socrates is a man, Socrates is mortal. This form of reasoning is called "syllogism" and has been described by the Greek philosopher Aristotle. It consists of a major premise, a minor premise and a conclusion. What happens to this reasoning if, let’s say, we discover that I am immortal? Is it still valid? Yes or no? Of course not, as I imagine all of you are thinking. We can't just ignore the exception and do as if nothing happened. The discovery of an exception ruins the validity of the major premise. Let's take an argument like this instead: All mothers love their children, Mary is a mother, Mary loves her child. What happens to this reasoning if, let’s say, we discover that there is a mother who does not love her child? Nothing. The major premise still holds, because it is not an absolute truth but a “most-of-the-times” truth, of a general and not universal nature. These last arguments are called by Aristotle "enthymemes" and are at the basis of a discussion. Enthymemes are rhetorical syllogisms in which the major premises are statements that are generally, not invariably true, and are accepted and shared by the human community. Let us now see a brief dialogue and try to interpret it in light of what we have just said about enthymemes. The argument is about whether or not to dye one's hair in extravagant colors. The person who is against this hair-dying thing says: "Well, what if they use the wrong cream and it actually hurts?" The person who is in favor replies: “Well, and what if you had a car accident? Would you say that driving is wrong?". Behind this interaction, there are two enthymemes, two rhetorical syllogisms. The first says: "Everything that can cause damage should not be done, dyeing your hair with an extravagant color can cause damage, therefore you should not dye your hair an extravagant color ". The second says: "Everything that can cause damage should not be done, driving is an activity that can cause damage, driving should not be done". The first reasoning is very evidently the weakest and there are several ways to deal with it. The second person chooses to show how, seemingly accepting the major premise, we reach an "absurd" conclusion. It is in fact evident that nobody wants to stop driving. The second interlocutor is therefore challenging the major premise itself, or rather its absolute interpretation. What she is saying is: "Not everything that can cause harm should not be done ...". From the example, we can clearly see how important it is, in a discussion, to do two things. The first one is to identify major premises that are "strong" and shared with the interlocutor, in order to build upon them and hopefully reach an agreement (this is not the case of the “dying your hair” example, but it can be, in other cases). The second thing to be done is to identify the major premises that our interlocutor uses to build his own argument, in order to decide whether we agree or not. And if not, challenge them (this is the case of the “dying your hair” example). You may ask: but is this relevant for scientific communication, which would seem much closer to the syllogism "all men are mortal, Socrates is a man, Socrates is mortal"? Actually, it is. In fact, we often find ourselves, even in the scientific arena, using rhetorical syllogisms that – and this must be underlined clearly – are no less “rational” than scientific syllogisms. Let's take an example. "Detecting mild cognitive impairment and frailty will be partially automated, thus making the monitoring of the elderly more efficient and the prevention of frailty more effective." This short text comes from the executive summary of a project proposal. The argument brought in favor of the approach entails some enthymemes. The main one is: "Anything that is automated is more efficient, the project automates the detection of mild cognitive impairment and frailty, therefore, the detection will be more efficient". The reasoning is completed by a cause-effect argument: "If cognitive impairment and frailty detection is improved, prevention is improved". This argument is embedded inside the first. We finish up this lesson with two observations. First of all, that the conclusion is drawn explicitly. It is an enthymeme in which two parts out of three are made explicit, namely the minor premise and the conclusion. Only the major premise is hidden. It is often the case with enthymemes to leave some parts to the audience to infer, like the major premise or the conclusions. In fact, drawing the conclusions has the advantage of giving "satisfaction" to the interlocutor and making his adhesion to the thesis more solid. In this case, instead, the conclusion is stated loud and clear. It is deemed to be the strong point of the project and it can’t be missed. The second observation is that the cause-effect argument is in some way taken for granted: the implicit way in which it is expressed makes it more difficult to discuss it and, if the case, to deny it. If, instead, it was explicit, like: "if we improve detection, we also improve prevention". It would be easier to question it. In the case of this project proposal, no harm is meant, but this “taking for granted” something can be used as a manipulative technique: you hide what you don’t want to discuss.