I believe that a good reasoning starts with structured thoughts. It helps to understand complex topics and to communicate them to others. Here is my list of reminders when I process something new:

Things don’t exist in a vacuum

It is a common approximation in high school physics to consider an object in a vacuum: no friction, no external forces except gravity. However, all students know that it is only a simplification. The results will be as good as the validity of the simplification.

Making simplifications when you are well aware of why you do them and what are their consequences is fine. But if you don’t, that is absolutely not fine!

My point is, in life, things don’t exist in a vacuum. We may isolate some elements but ultimately, objects are connected and interact with each other. So the local conclusion drawn from isolating a few elements will not generalize well.

In short, in a complex system, the connections between elements cannot be neglected.

Thinking dynamically

In physics, there is a reason why students learn about static systems* before dynamic ones. Dynamic systems are more complex to understand. Their behavior cannot be derived from a succession of static states because it is determined by differential equations and transitional stages matter.

The same applies in life in general. Reflections based on static situations will probably not generalize to dynamic cases

Second order thinking

Any decision we make or action we take have consequences. Taking these into account is first order thinking. In addition, these consequences will have their own consequences, so on and so forth. It’s important to consider these second order consequences (and higher orders, though less predictable). We will never fully control all consequences. The point is to avoid preventable ripple effects.

Authority arguments don’t matter

Groups look for consensus, which we can call political truth. It doesn’t need to be objectively true as long as the majority agrees on it. That is exactly what we want to avoid when reasoning. We want scientific truth, which is verifiable, repeatable and provide explanations.

Authority arguments which are not grounded on scientific truth should not be considered.

Moral arguments are dangerous

These arguments are very similar to authority arguments. Indeed, moral values are a set of ideas shared by a group. But few people know what they mean and where they come from.

This would be enough to discredit them. But moral arguments are also pernicious because of their manipulative nature. They imply that there is a ‘good’ and ‘bad’ sides. Of course, if you are not on the ‘good side’ (defined arbitrarily), you are an enemy of the tribe. The tribe can now use all kind of despicable means against you, even if prohibited by their own moral values.*

In short, moral arguments are a shield some people use to protect their ideas. Then they use this shield to smash the sh*t out of you.

The natural is the default option

Standing the test of time is the ultimate proof. That is the case of all natural things (present in nature). So when hesitating between something unnatural and its natural alternative, the unnatural needs to prove itself. For example, new drugs need to prove they do not harm people. Similarly, chemical companies need to prove that their pesticides do not harm people and nature.

Argument from ignorance

It is a kind of logical fallacy (more information on the wikipedia page). Several errors can be made under the argument from ignorance. My favorite are:

• “Absence of evidence is not evidence of absence”. Never seeing a black swan (absence of evidence) does not prove that they don’t exist (evidence of absence)*.
• Your knowledge or understanding of something has no influence over its veracity.

A side note here. We tend to consider that our thoughts are likely to be true, often without much evidence to back them up. But your thoughts can be complete garbage and so can mine.

No utopia allowed

I have been the victim of this one more than once. Giving too much weight to an idea because “it should be like that…”.

Use first principles

Not going to paraphrase: First Principles, from Farnam Street

Look through the lens of game theory

Especially useful when considering situations involving people. I usually ask myself what could be someone’s motives or incentives? What goal is he or she after? Money, status, power, satisfying an inner need?

Once that is clear, I look at the strategy they are using. If possible, I also consider alternative strategies or moves they could have done***.

Thinking statistically

• Don’t assume you have all the data
• Consider a decent confidence interval for your data points
• If you don’t have all the information you want, you need to rely on the robustness of your decision making process.

Scepticism

• Scepticism without a method is simply cherry-picking and BS
• If you are sceptical about something, you must research the topic instead of relying on your guts

Sanity check

Know the order of magnitude of the phenomena you are considering. Objects hotter than the surface of the sun are unlikely in the everyday life, same when the torque you calculated for your small electrical motor is larger than the one generated by a truck’s engine. It also applies to things you are not familiar with, like death rate of a disease, death or complication from a vaccine.

Do your homework

You won’t come up with a strong argumentation if you are unprepared. If you don’t know enough about a topic, you will be better off not speaking about it. The more you say, the more likely you are to say something foolish” (R. Greene)

Obvious

Expand your knowledge, look for the unknown and what you disagree with. Be able to pitch the opposite side of an argument.

*: I include systems with a constant speed within the static ones. Their acceleration is zero which simplifies the model.

*: Any ressemblance with reality is on purpose.

*: Black swan naturally live in Australia so they have been discovered lately compared to their white counter parts.

***(Borderline off topic): When thinking in terms of opposite strategies, two cases are very interesting:

When the current situation does not provide enough information to know which strategy or hypothesis is correct. Let’s use a far fetched example. Common knowledge says that magic doesn’t exist. if you openly believe in magic, people will assume you are crazy. There are 2 cases here: either, magic does not exist, and the crowd is correct. Or, magic does exist, but wizards know that they would be chased or used as guinea pigs if any sane person knows about their existence. Then it is in their best interest to let everyone believe that you are crazy. In the end, the result is the same, the majority believes that it does not exist and everyone with a different opinion is considered mad.

The second case is the irrelevant alternative. One of the 2 alternatives you consider is so opposed to your goal that you have no interest in choosing it. Any test asking you if you are criminal is an example of that. For the person acting, the choice is obvious because one alternative is irrelevant. However someone could think that you answered honestly. Don’t fall in such a trap, if only one answer is socially (or legally) acceptable, you didn’t learn anything from this answer.