PHIL 57, section 7

- LECTURE #7 –

October 22, 2003

- BACK -

What's happening today?

Assignment for next week

Problem Set #5

READING

HURLEY, 9.3 (you should also skim 9.4)

Taking Sides, Issue 15, "Will the Digital/ Computer World Lead to Greater Individual Freedom"", 266-280.

Tests back near the end of class, we will discuss them.

Average is a 75.

Lecture on 9.2.

Argument clinic on the issues you wrote about at the end of the test.

CAUSALITY AND MILL'S METHODS

Causation is an ambiguous term. When we speak of some event or state of affairs as being the cause of something else, we must specify what we mean. A may be a necessary condition of B, a sufficient condition, or a necessary and sufficient condition.

NECESSARY CONDITION - The condition without which something cannot occur. Example: Oxygen is a necessary condition for fire.

SUFFICIENT CONDITION - Condition in the presence of which an event occurs. Example: rain is a sufficient condition for a wet sidewalk, but not necessary -- sidewalks can be wetted by a sprinkler or even Fido.

NECESSARY AND SUFFICIENT CONDITION - Combination of the previous two. Force is a necessary and sufficient condition for a body to accelerate -- nothing more and nothing less is required.

Method of Agreement: If the instances of phenomenon or state of affairs under investigation have only one circumstance in common, the sole circumstance in which all agree is the cause (or effect) of the given phenomenon or state of affairs.

Method of Difference: If there are two instances, one in which the phenomena or state of affairs under investigation occurs, and the other in which it does not, and the two have everything in common except for one aspect, that one aspect is either the cause, the effect, or an essential part of the cause of the phenomenon or state of affairs under consideration.

Joint Method of Agreement and Difference: If two or more instances in which the phenomenon or state of affairs occurs have only one aspect in common, while two or more instances inn which it does not occur have nothing in common (except for the absence of the former aspect), the aspect which is the sole difference between the two sets is the effect, cause, or and indispensable part of the cause of the phenomenon or state of affairs.

Method of Concomitant Variations: Whatever phenomenon or state of affairs that varies in any aspect whenever another phenomenon or state of affairs varies in some specific way, is either a cause or an effect of the second phenomenon, or it is at least causally connected with it in some way.

Method of Residues: You subtract known and causal connections from other (more complex) causal relations, with the remaining relation being the candidate for the causal relation under consideration.

METHOD OF AGREEMENT

A systematic effort to find a single factor which is common to a number of occurrences with the intention of identifying the causal factor.

Person A ate an enchilada at Jim's Waffle Shack.

So did persons B, C, D and E.

They are all sick.

Jim's Waffle Shack enchiladas are the cause.

You must ignore the other condition that are SUFFICIENT but not NECESSARY. Jim's enchiladas are a necessary condition because it is a shared element in all of the cases of sickness.

The conclusions are only probable (as is everything in INDUCTIVE LOGIC).

	We will have a detailed discussion about PROBABILITY next time.
	Something or some alternative explanation (a combination of two causes) could be overlooked.

The necessary condition does not state that everyone who ate Jim's enchiladas will get sick -- what is says is that everyone who got sick must have ate Jim's enchiladas.

METHOD OF DIFFERENCE

Systematic search for an element which is present when an event occurs, and absent when an event does not occur. It may only be used with two (2) occurences and identifies a SUFFICIENT condition.

A pair of twins, Jane and Jan, have dinner in a restaurant. The twins have identical susceptibilities to food poisoning. Jane orders soup (A), salad (B), chicken (C), carrots (D), rice (E), enchiladas (F) and ice cream (G). Jan orders soup (A), salad (B), chicken (C), carrots (D), rice (E), enchiladas (F) and NO ice cream (G). Later, Jan gets sick from something she ate, but Jane does not. What food caused Jan's sickness. (Hurley 491)

CHART ON BOARD

			possible	sufficient	conditions
Occurence	A	B	C	D	E	F	G	Sickness
	*	*	*	*	*	*	*	*
	*	*	*	*	*	*	-	-

Because it pertains to only two (2) instances, it is not as easily generalized as the method of agreement (which pertains to several instances).

The conclusion is only probable -- even for the two instances under consideration.

JOINT METHOD OF AGREEMENT AND DIFFERENCE

"a systematic effort to identify a single condition that is present in two or more occurrences in which the phenomenon in question is present and that is absent from two or more occurrences in which the phenomenon is absent." (Hurley 493)

"Six people eat dinner in a restaurant. Liz (1) has soup (A), a hamburger (B), ice cream (C), Freedom fries (D), and mixed vegetables (E). Tom (2) has salad (F), soup (A), fish (G), mixed vegetables (E), and ice cream (C). Andy (3) has salad (F), a hamburger (B), Freedom fries (D), and ice cream (C). Sue (4) has Freedom fries (D), a hamburger (B), and salad (F). Meg (5) has fish (G) and mixed vegetables (E). Bill (6) has Freedom fries (D), a hamburger (B), and soup (A). Later, Liz, Tom, and Andy get sick from something they ate, but Sue, Meg, and Bill do not. What food made them sick?" (Hurley 492)

CHART ON BOARD

		possible	necessary	or	sufficient	conditions		Phenomenon
Occurence	A	B	C	D	E	F	G	Sickness
1	-	*	*	-	*	*	*	*
2	*	*	-	*	*	-	*	*
3	*	-	*	-	*	*	-	*
4	*	-	*	-	-	*	-	-
5	-	-	-	*	-	-	*	-
6	-	*	*	-	-	*	-	-

Mixed veggies bad.

Because a cause which is both a necessary and sufficient condition is arrived at, the conclusion is stronger than either of the previous two. However, the generalization's strength is proportional to the number of cases that are included.

METHOD OF RESIDUES

"consists of separating from a group of causally connected conditions and phenomena those strands of causal connection that are already known, and leaving the required causal connection as the 'residue'." (Hurley 494)

"After occupying his new house Mr. Smith found it drafty. he traced the source of the draft to three conditions: a broken window in the garage, a crack under the front door, and a broken damper in the fireplace. When the window was replaced he noticed an improvement, and a further improvement when weather stripping was installed on the door. He concluded that the draft that remained was caused by the broken damper in the fireplace.

'ABC' causes 'abc.' (these things cause total draft).

A causes a. (Window causes draft a)

B causes b. (Door causes draft b)

Therefore, C causes c. (damper causes remaining draft)

METHOD OF CONCOMITANT VARIATION

"identifying a functional relation (perhaps expressible in an equation) between a factor F that admits of quantity or degree and a factor E that admits of quantity or degree, such that variations in the quantity of F correspond with variations in the quantity of E. This functional relation may be DIRECT or INVERSE. When such a relation is found, it may be concluded that F and E are probably causally related." (Hurley B 134)

"In attempting to diagnose Mrs. Thompson's high blood pressure, a cardiologist noticed a correlation between fluctuations in blood pressure (B) and certain brain waves (Y). As the blood pressure incresed, so did the intensity of the brain waves, and as the blood pressure decreased, the intensity of the brain waves decreased. The cardiologist concluded that the two conditions were causally related." (Hurley 494)

DIRECT METHOD

(A B C) is coincident with (X Y Z)

(A B+ C) is coincident with (X Y+ Z)

(A B- C) is coincident with (X Y- Z)

Therefore, B is causally connected to Y. Though we do not know the cause. Further investigation may show a temporal ordering, showing which way the causation runs.

"(A B C) is a set of observable conditions such as cholesterol level, liver function, basal metabolism, etc., with B representing blood pressure; and (X Y Z) is another set of observable conditions with Y representing certain brain waves." + and - stand for increase or decrease in the given condition.

INDIRECT METHOD

(A B C) is coincident with (X Y Z)

(A B+ C) is coincident with (X Y- Z)

(A B- C) is coincident with (X Y+ Z)

Therefore, B is causally connected to Y.

When B increases, an increase in Y is measured, and when Y is elevated, there is a lowering in B measured. This CONCOMITANT VARIATION (variation occurs at the same time) shows that there is a causal relation, though, once again, the order of the causation requires further investigation.

PROBLEMS FROM THE TEXT

Identify the kind of causality intended by the following statements. Is the cause a sufficient condition, necessary condition, or both sufficient and necessary condition?

Throwing a brick through a window will cause the window to break.
Sufficient condition. There are other ways to break the window.

Heating an iron rod causes it to expand.
Sufficient and necessary condition.

Slashing an inflated automobile tire with a knife will cause it to go flat.
Sufficient condition. There are other ways the tire will go flat.

Releasing the shutter of a camera causes an image to appear on the film.
Necessary condition. There are other conditions that need to be met (reality must exist, there needs to be film, light, etc.)

Pulling a trigger of a gun causes it to fire.
Necessary condition. You need to load the gun as well.

Wetting litmus paper with an acid causes it to turn red.
Sufficient and necessary condition.

Identify which of Mill's methods is being used in each of the following inferences: (Hurley B, 134)

Virus V was found in every case of sinusitis that we examined. We conclude, then, that virus V is a cause of sinusitis.
Direct method of agreement.

We compared two classes of rats, one with stunted growth and one without stunted growth. The stunted rats had an unusual amount of calcium in their early diets, whereas the nonstunted rats had early diets with a normal amount of calcium. We concluded that abnormal amounts of calcium in the early diet or rats is a cause of stunting in their growth.
Method of difference.

Plants with root rot are4 always found to be heavily watered. We have never seen a plant withough root rot that was heavily watered. It can be concluded, then, that heavy watering of plants causes them to have root rot.
Joint method of agreement and difference.

	Because it pertains to only two (2) instances, it is not as easily generalized as the method of agreement (which pertains to several instances).
	The conclusion is only probable -- even for the two instances under consideration.

	Mixed veggies bad.
	Because a cause which is both a necessary and sufficient condition is arrived at, the conclusion is stronger than either of the previous two. However, the generalization's strength is proportional to the number of cases that are included.