Logic and
Critical Thinking

Philosophy 4

Gale Justin

The objective of today’s class is learn how to distinguish arguments from explanations.

uWe begin by reminding ourselves of what an argument is.

uWe then compare a passage that contains an inductive argument with a passage that contains a deductive argument.

uFinally, we look at the difference between an argument and an explanation.

An argument is a group of propositions (or statements). The statements have a certain kind of relationship to one another. Specifically, one or more of the statements is given as a reason to accept the truth of one other statement.

The statements that give the reasons are called “premises”—abbreviated by “P” and the statement that is being supported by the reasons (or reason) is the “conclusion”—abbreviated by “C.”

Here is one argument (A1):

C: First and Richmond needs a 4-way stop.

P: The heavy traffic is a danger to children crossing there on the way to school.

P: The drivers of cars on the two sides with stop signs are not easily able to see the approaching cars on the two sides that do not have stop signs.

Here is a second argument (A2):

C: Lee could not have set the fire.

P: The fire broke out at 3 p.m. on Tuesday.

P: Four of Lee’s co-workers saw him at work from 9 a.m. to 5 p.m. on Tuesday.

P: A person cannot be at two places at exactly the same time.

A1 and A2 are different kinds of arguments.

uA1 is an inductive argument. Its premises provide good reasons for, but do not guarantee, the truth of the conclusion.

uThere might be evidence (i.e. a premise) that conflicts with a premise used to support the conclusion.

uFor example, the premise “There is a school crossing guard stationed at the intersection during the times that the children cross the intersection.

With respect to A2:

uIt is a deductive argument.

uIf its premises are true, then the conclusion must be true.

uSo the truth of its premises guarantee the truth of the conclusion.

uGiven the truth of the premises, no evidence could weaken (or strengthen) the conclusion.

When reading a passage, the best way to begin the process of extracting its argument is to identify the conclusion. That is,

uAsk yourself first “What am I supposed to believe as a result of reading this passage?” Whatever that is, that is likely to be the conclusion.

uThen identify the premise(s) by asking “What reasons are given for me to believe that the conclusion is true?”

To decide whether an argument is inductive or deductive:

uAsk yourself “Can I think of any possible circumstance that would either strengthen or weaken the conclusion?” or

u“Is the conclusion implicitly contained in the premises, so that if the premises are true, the conclusion must be true?”

An argument:

uIs Inductive if you can I think of any possible circumstance that would either strengthen or weaken the conclusion.

uIs deductive if the conclusion is implicitly contained in the premises, so that if the premises are true, the conclusion must be true.

Not all pieces of reasoning are, however, arguments. Some are explanations.

Here are two examples of explanations:

uAn Amtrak train derailed on Wednesday, injuring 74 people. It jumped a track that had been tampered with.

uThe blood supply at the county blood bank is running low. The shortage is due to a greater than usual number of open heart surgeries coupled with the fact that fewer people are donating blood.

The crucial difference between an explanation and an argument is this:

uAn explanation is given an event that has actually occurred and that could be directly known by someone who happens to witness the event.

uAn argument is given for an opinion that can only be indirectly known on the basis of the reasons that are offered as support for the opinion.

Consider:

u“An Amtrak train derailed on Wednesday, injuring 74 people.”

u“First and Richmond needs a 4-way stop.”

Notice that:

uThat the Amtrak train derailed is an event that is directly known by whoever reported the derailment.

uThat there needs to be a 4-way stop at First and Richmond is an opinion that is known not directly (by spotting the “need”) but through the reasons that are given to support the opinion.

Which of the following get explained and which get supported?

uHe should get first-degree murder.

uThe dynamite exploded.

uSteve’s car was almost certainly burgled.

uDanny Hamilton left his rig on the east bound side of I-50.

uDanny Hamilton was abducted by loan sharks.

To elaborate on the distinction:

uAn explanation is for an event that has happened and has been observed by someone. The explanation of the event is given to increase your understanding of the event by citing the cause or what is believed to be the cause of the event.

uAn argument makes a recommendation, a prediction, or expresses a point of view. The truth of a recommendation, a prediction, or a point of view cannot (or cannot yet) be directly known. So support is offered for such statements.

How to distinguish between explanations and arguments:

uAsk yourself: “Is the point of the passage to tell you why something that can be directly known has happened?” or

u“Is the point of the passage to persuade you of some statement that can only be indirectly known through the reasons that are intended to support the statement?”

Now do group work on distinguishing arguments from explanations.

Standard form of Explanations:

uConsider: “An Amtrak train derailed on Wednesday, injuring 74 people. It jumped a track that had been tampered with.

uExplanadum: An Amtrak train derailed on Wednesday, injuring 74 people.

uExplanans: It jumped a track that had been tampered with.

The terms used to identify parts of the explanation have the following meanings:

uExplanadum: This term denotes or refers to the event being explained.

uExplanans: This term denotes or refers to the condition(s) that is being offered to explain why or how the event occurred.

Note:

uThe explanadum (the event being explained) CAN be directly known, even if you are not at the moment in a position to know it.

uThe explanans (the conditions that are thought to have caused the event) may be disputed or may themselves require evidence or support. Nevertheless, they are accepted as being true in the explanatory passage under examination.

One Complication:

uIn some cases, a passage can function as both an argument and an explanation.

uThese cases are usually ones in which a passage asserts a causal connection asserted between two items and goes on to give an explanation of the causal connection. The explanation also serves as support for the causal connection.

For example:

uPrima Indians have relatively low rates of heart disease despite their high rate of obesity. [Because] They have a high amount of good cholesterol.

uSun bathing causes skin cancer.

[Because] Ultraviolet rays genetically alter skin

cells.