How to Recognize an Argument When You See One (Or How We Think — Some Simple Ways)

You’re late for class. You dash out onto the street against the light, hoagie in hand, hoping to  hit campus running. Out of the corner of your eye, you glimpse a truck accelerating to meet you. “Instinctively,” you stop short and quickly step back to the safety of the curb. 

How do we explain what just happened? You might be tempted to describe your behavior as accomplished “without thinking.” However, we can also cast it as the product of a quick bit of reasoning of the form: 

(P1) All heavy objects cause damage or death when they strike creatures like me.
(P2) A heavy object (truck) is speeding towards me.

∴ The truck will damage or kill me if it hits me.

P1 and P2 are premises that function as evidence for the conclusion, the sentence below the line. You’re so practiced at this type of reasoning, though, that you don’t need to work through it consciously (and it’s probably a good thing, too). 

Sets of sentences in which one (the conclusion) is supported by a group of others (the premises) are arguments. In their explicit form, these machines of persuasion constitute the fundamental currency of academic discourse. Whether writing in the sciences, the humanities, or the law, authors present claims and attempt to support those claims through evidence and analysis. Ideally, an author wants to make clear to their readers exactly how their claims or conclusions follow naturally from the evidence she provides. “Following naturally” amounts to the compelling “mental movement” from premises to conclusion conforming to certain patterns of inference known to be truth preserving.

How to Know an Argument When You See One

Though few authors will ever attempt to push you out of the way of oncoming traffic (at least not literally), nearly all the work you will encounter in your courses over the next few years will involve understanding and responding to what such writers are trying to convince you is the case. But you’ll quickly notice that simply locating the argument is often the most challenging part. As you might expect, most authors want their readers to feel the pressure of their reasoning and  therefore rely upon certain typical moves to advance the steps of their arguments when supporting a claim. Common words indicating premises include: 

on account of

Authors often indicate conclusions using: 


If the argument or reasoning proves lengthy and complicated (which it often will), you might find it beneficial to paraphrase its premises and conclusions into a shorter, standard form that lays its reasoning bare. Let’s look at a few simple examples:

His power, we allow, is infinite; whatever he wills is executed; but neither man nor any other animal is happy; therefore, he does not will their happiness.

— David Hume

We can rewrite Hume's short argument in this way:

(P1) His power, we allow, is infinite.
(P2) Whatever he wills is executed.
(P3) Neither man nor animal is happy. 

∴He does not will their happiness

Most arguments can be written in a number of ways. For example, we can also represent Hume’s reasoning as:

(P1) His power is infinite.
(P2) If he wills happiness, happiness will be executed
(P3) Neither man nor animal is happy. 

∴He does not will their happiness

(In case you're curious, this last argument is an example of modus tollens reasoning.)

Consider this slightly more involved example Socrates gives in Plato's Apology:

Let us reflect in this way, too, that there is good hope that death is a blessing for it is one of two things: either the dead are nothing and have no perception of anything, or it is, as we are told, a change and a relocating for the soul from here to another place. If it is complete lack of perception, like a dreamless sleep, then death would be a great advantage...for all eternity would then seem to be no more than a single night. If, on the other hand, death is a change from here to another place, and what we are told is true and all who have died are there, what greater blessing could there be, gentlemen of the jury?... Most important, I could spend my time testing and  examining people there, as I do here, as to who among them is wise, and who thinks he is, but is not.

We can recast Socrates's reasoning as:

(P1) Either the dead have no perception or their souls are relocated to another place.

(P2) If being dead is like having no perception, a deep dreamless sleep, death will be a great advantage. 

(P3) If death is a relocation to another place where the past dead reside, it would be a great blessing, for I could examine the wisdom of the greatest minds. 

∴Death is a blessing. 

As we can see, Socrates presents the results of death as a dichotomy (a choice with only two options) and then argues that either alternative proves desirable. Given that all possibilities are positive, Socrates concludes that death as such is a blessing. Do you agree? If you were to deny the conclusion, how would you show that Socrates is incorrect?

Think you've got the idea? Great! Try rewriting this passage from John Stuart Mill yourself:

It is by no means established that the brain of a woman is smaller than that of a man. If it is inferred merely because a woman's bodily frame generally is of less dimensions than a man's, this criterion would lead to strange consequences. A tall and large-boned man must on this showing be wonderfully superior in intelligence to  a small man, and an elephant or a whale must prodigiously excel mankind.

Types of Arguments: Deductive v. Inductive

Formalized arguments can be broadly grouped into two categories: deductive and inductive. These two kinds are distinguished by the relationship between their premises and conclusions.

Deductive arguments are assessed in terms of their validity or invalidity. An argument’s validity is judged only by the inferential relation between its premises and its conclusion. That is, the premises need not be true for an argument to be valid. For example:

(P1) All Kansans are evil.
(P2) My mother is a Kansan. 

∴ My mother is evil.

If we assume that P1 and P2 are true, then the conclusion inexorably follows. (The premises aren't true in this case, though — my mother happens to be non-evil). If the premises of a valid deductive argument are indeed true, the conclusion must be true, and the argument is considered sound

Inductive arguments, in contrast, inhabit a spectrum from weak to strong. Conclusions to  arguments of this type go beyond their premises and hence cannot be guaranteed true, regardless of the truth of the premises. Even if its premises are true, an inductive argument’s conclusion is at best probably true (or strong). Consider the following example: 

(P1) Nearly all deaf persons have little musical ability.
(P2) Beethoven was deaf. 

∴ Beethoven had little musical ability.

P1 and P2 are both true, yet the conclusion is certainly false. Hence, though inductive arguments are a primary source of our beliefs — probably an overwhelming number of our beliefs — they remain a tentative source of knowledge. 

Deductive and inductive arguments often work in conjunction. Returning to the truck example with which we began, we can spell out the implicit reasoning even further: 

(P1) All heavy objects cause damage or death when they strike creatures like me. (Conclusion from previous induction)

(P2) A heavy object (truck) is speeding towards me.
(Learned via sense perception)

∴ The truck will damage or kill me if it hits me.
(Deductive inference)

Perhaps some speeding heavy object will mysteriously not damage or kill creatures like me if it hits me, but given the history of such collisions, it's reasonable for me to conclude inductively a general rule about what would likely happen. That inductive conclusion can then serve as a premise in a deductive argument that will (hopefully) cause me to move out of the way in time.

Arguments presented in academic essays will rarely fit neatly into the forms sketched here, though authors often strive to cast their cases in a broadly deductive shape to lend their conclusions additional force — after all, they want you to believe that their conclusions must be true. Regardless of the shape of your own reasoning, the truck example can serve as a metaphor for your own writing. You want the evidence you present in your essays to create mental movement. Good, strong arguments push intelligent readers along certain routes of inference. Make no mistake; an argument can move you.