PHIL 2030: Introduction to Ethics
Dr. Robert Lane
Lecture Notes: Tuesday January 14, 2014



[2.7.] Soundness.


When we critically evaluate an ethical argument, we will be asking two related, but distinct, questions:

1. Is it valid? [concerns the LOGICAL ASPECT of the argument]

2. Are all of the premises true? [concerns its FACTUAL or MATERIAL ASPECT]


If the answer to both questions is “yes,” then the argument is said to be sound.


soundness (df.): A sound argument is an argument that (1) is valid and (2) has all true premises.


But if the answer to either question is “no,” then the argument is not sound, and we should reject it.


[See previous lecture notes for the arguments referenced here…] So argument (A) is sound, since it meets both of these conditions; argument (B) is unsound, since it has a false premise; and arguments (C) and (D) are unsound, since they are not valid.


The fact that an argument is not sound does not mean that its conclusion is false. Showing that an argument is bad is very different than showing that the conclusion of the argument is false. All that can be concluded from the fact that an argument is unsound is that the conclusion has not been proved true by that argument, and a different argument is needed to support the conclusion. This is illustrated by argument (C)…


  1. Atlanta is located in Georgia. (premise) (T)
  2. The moon orbits the earth. (premise) (T)
  3. Therefore, Barack Obama is President. (conclusion) (T)


 as well as by this argument:


  1. Miley Cyrus is a Nobel Prize-winning physicist.
  2. All Nobel Prize-winning physicists are internationally famous.
  3. So, Miley Cyrus is internationally famous. [valid, but with two false premises]



There are some arguments that are good in their logical aspect, even though they are not valid. These are sometimes called inductive arguments.

·         In these arguments, the truth of the premises would provide a very good reason for thinking the conclusion is true, but would not guarantee the truth of the conclusion. For the most part, we will not be discussing those types of arguments in this class.

·         The majority of the arguments we discuss in this class will be either valid or logically bad. To learn about these other types of arguments, you can take the Philosophy Program’s Critical Thinking course (PHIL 2020; 3 hrs credit in core area B).



[2.8.] The Limited Cultural Differences Argument.


To illustrate some further, simple points about philosophical arguments, we will consider a specific ethical claim, as well as an argument for this claim.


Different societies disagree about the morality of certain actions. For example, in traditional Eskimo (Inuit) society, infanticide (df.: the killing of a newborn baby) is believed to be morally permissible (not immoral) in certain circumstances (in these circumstances, it is left up to the parents to decide whether to kill the infant; there is no social stigma attached to the practice; it is more common with baby girls than with boys).[1]


But in contemporary American society, killing an infant is believed to be immoral, no matter what the circumstances. (You will read more about this practice of the Eskimos in EMP 2.5).


Here is the argument that Rachels asks us to consider (argument #4 on RTD p.23). I will call it the Limited Cultural Differences Argument (LCDA) (I have changed it slightly to make it clearer; I have also given it a different name than it has in the textbook):


1.      In some societies, infanticide is believed to be morally permissible (not immoral).

2.      In other societies, infanticide is believed to be immoral.

3.      Therefore, infanticide is neither objectively morally permissible nor objectively immoral; there is no objective fact of the matter, only beliefs about whether or not it is immoral.


Discussion: Is this a valid argument? Does it have true premises?



[2.8.1.] Objectivity.


The word “objective” plays a crucial role in the Limited Cultural Differences Argument (LCDA). The word is a familiar one, but it is not the easiest term to define precisely.


In the LCDA, the word “objective” means something like this:


objective (df.): something is objective when it is independent of what anyone believes, thinks, or feels about it.

·         “It is objectively true that p” =  “it is true that p, whether or not anyone believes that p.”

·         For example: it is objectively true that the earth orbits the sun; that water is H2O; and that 2+2=4.

·         A word that means nearly the same thing as “objective” is “real.”[2]


“Objective” is the opposite of “subjective.”


subjective (df.): something is subjective when there is no truth or fact of the matter about it, only opinions, beliefs or feelings about it. For example, whether Turkey and Gravy Soda is delicious is a subjective matter.  [But whether I like Turkey and Gravy Soda is an objective fact about me.]

[2.8.2.] Moral Skepticism and Moral Realism.


The conclusion of the LCDA expresses a view called moral skepticism. This argument is supposed to show that there is no truth of the matter about the morality of killing infants, that there is no objective right or wrong when it comes to infanticide. The only truths that are relevant to the morality of infanticide are truths about what people in different societies believe.


moral skepticism (df.): the view that there is no such thing as objective moral truth, i.e., no moral judgments that are true (or false) independent of what people think, feel or believe about them.

·         One may be a moral skeptic about all morality (call this “full blown” moral skepticism) or just about specific issues, such as infanticide (call this “limited” moral skepticism).



The Limited Cultural Differences Argument is an argument for limited moral skepticism (about infanticide); its conclusion is that when it comes to the morality of infanticide, there is no such thing as objective right or wrong—there is only beliefs, opinions, feelings about whether it is right or wrong.



Stopping point for Tuesday January 14. For next time, study the lecture notes from today, and finish reading RTD ch.2. You may have a pop quiz on both at the beginning of class.



[1] For more on the practice of infanticide among some tribes of Inuit people, see Milton Freeman, “A Social and Ecologic Analysis of Systematic Female Infanticide among the Netsilik Eskimo,” American Anthropologist 73 (5), 1971, URL = < >, accessed August 29, 2011. But also note the following claim, made by a more recent researcher: “While there is little disagreement that there were examples of infanticide in Inuit communities, it is presently not known the depth and breadth of these incidents. The research is neither complete nor conclusive to allow for a determination of whether infanticide was a rare or a widely practiced event.” Andrew Hund, “Inuit.” In The Encyclopedia of Infanticide, Edwin Mellen Press, 2010.


[2] I derive this definition of the word "objective" from the definition of the word “real” given by the American philosopher Charles S. Peirce (1839-1914). Peirce is covered in American Philosophy (PHIL 3120; class web site: . Peirce himself derived the definition from the medieval philosopher Duns Scotus (1265/66-1308). [  ]

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