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reader comments: begging the question

Fri, 12 Nov 
Hi And welcome to your 1738th email of the day, which is about Begging the Question :-) I don't think all your examples work. For example:

A1.Abortion is the unjustified killing of a human being and as such is murder. A2.Murder is illegal. A3.So abortion should be illegal.

This has the same structure as:

S1.All men are mortal. S2.Socrates is a man. S3.So Socrates is mortal.

which for quite some time has been seen as a model of logic, not as an example of begging the question. 

reply: Begging the question is not a formal fallacy. There is nothing wrong with the form of the examples I have used. They are all valid arguments, or can be made so quite simply. Being valid only means that they commit no formal fallacy. Begging the question is often referred to as a fallacy of presumption or a fallacy of assumption because the error is in assuming what one asserts to be proving. The example you give is not a model of logic, but a model of a valid argument in predicate logic. Some would say that this model begs the question, but since its premises are not questionable, I would say it is a cogent argument. Validity is independent of the truth of the premises and vice-versa.

Look at this one step at a time.

A1 is the unsupported assertion that abortion is murder. S1 is the unsupported assertion that all men are mortal. The support for these assertions, if any support is to be found, lies outside the syllogism. In A1, the speaker perceives abortion to be a kind of murder; in S1, the speaker perceives men to be a kind of mortal creature.

Steps A2 and S2 don't seem to be very contentious.

reply: Neither does S1.

Steps A3 and S3 are interesting. Step S3 seems irrefutable, while I could well imagine an alternate A3:

A3':So we should legalise some kinds of murder.

reply: We call that a non sequitur. 

Hmm. Now that I've reached this conclusion, I don't know what to make of it! I wasn't expecting this at all. I still don't think it has anything to do with question-begging. Perhaps the topic of argument A is less cut-and-dried than the topic of argument S, which is why we spend more time discussing abortion than whether Socrates is, or was, mortal.

reply: If by topics, you mean the assumptions that abortion is murder and that all men are mortal, and if by cut-and-dried you mean warranted as an assumption, then you are right. Few people would be unwilling to grant the assumption that all men are mortal. (There are some, however, and you may read about them elsewhere in the Skeptic's Dictionary or seek them out on the Internet, e.g., Alex Chieu.) While many would call the assumption that abortion is murder unwarranted.

The "paranormal experiences" argument also does not seem to be circular. Substitute "reality" for "paranormal phenomena" to get:

"Reality exists because I have had experiences that can only be described as real."

Is that really circular? It seems to be no different from "reality exists because I can see and touch it, and it does not appear to be a dream" - which is roughly my day-to-day definition of reality. (Not that I need a definition, most days.)

reply: To continue this discussion would be circular. But....begging the question is not a formal fallacy and is not a claim as to the invalidity of the reasoning, etc. etc.

Anyhow, keep up the good work!
Norman Paterson, University of St Andrews 

reply: You've been hanging around the Central Bar, haven't you?

begging the question