Informal Logic 101: How to Think and Argue Better, Part 6

Part 6: Avoiding Presumptions

“A presumption becomes a self-refuting assertion.”   — R. Alan Woods

Following hot on the heels of “Part 5: Facts Over Feelings”, today’s logical fallacies involve inappropriate presumptions that confuse and invalidate one’s argument. (Of course, I would never do this! … OK, OK, maybe.) Sometimes when making a case or defending a position, it’s easy to get trapped within our own perspective, so to speak. We might take something for granted in our reasoning — a premise, for example, that asserts something as true when, in fact, it also should be verified. (If you recognize this, you may acknowledge that it needs to be examined further but agree, or ask the other party, to provisionally accept it for the sake of discussion.) Regardless of the form this takes, it ends up destroying the argument, because nothing is actually proven.

Professor Samples gives three types of this class of fallacy, as follows:

alien with I Want to Believe poster of NASA shuttleWishful thinking

Just because someone accuses you of wishful thinking does not necessarily mean that’s what you are actually doing. It depends on your rationale, so this calls for a little introspection. Do you want something to be true (or false) so much that you are assuming it must be true (or false)? If so, then you may indeed be guilty of assuming that’s the case, because it works in favor of your desired conclusion. That is wishful thinking.


Distraught woman:

“I found a lump in my breast. But, I don’t want to go to the doctor for an exam/biopsy, because she might tell me I have cancer. So, I’m not gonna go.”

In this woman’s mind, if no doctor tells her she has cancer, then she doesn’t have cancer. The problem is that her worries and wishes do not determine reality. Either she has cancer, or she doesn’t. If so, it’s going to affect her health, regardless of what she wants to believe.

Misguided Christian:

“God has a ‘perfect plan’ for my life. As long as I follow Jesus and the leading of the Holy Spirit, He’ll lead me to the perfect spouse, perfect job(s), and into a wonderful and blessed life without hardship or tragedy.”

Regrettably, some Christians do think like this. But, it is based on some very questionable interpretations of select Biblical passages that do not necessarily mean what they think they mean. Plus, any honest assessment of the lives of other Christians — even the most devout and “saintly” — demonstrates that things just don’t work out that way 99.99% of the time. (Yes, I made up that statistic.) Still, they cling to the idea.

Getting back to my initial statement on “wishful thinking”, it is also quite possible that your accuser’s own presumptions are preventing him/her from thinking clearly enough to consider your argument. In that case, there’s probably some wishful thinking going on on their part. Depending on time and circumstances, this might be fruitful to pursue, or it might be an ill-advised bunny trail.

Petitio principii (aka “Begging the question”)

You knew there’d be some Latin, right?

Although Professor Samples does not address it in his book, I’d like to make a distinction here between this fallacy and two others, because I get them confused all the time. There is something called the “No true Scotsman” fallacy, which is a form of begging the question, which is in turn a form of circular reasoning, i.e., circulus in probando. (Except, some classify circular reasoning as a form of begging the question, and circulus in probando is sometimes reserved for the subset known as “vicious circle”. Aargh!) I will probably address the broader problem of circular reasoning and the specific variation of “No true Scotsman” in a post at a later date. For now, I’ll try to focus on begging the question in a non-Scotsmanlike fashion.

This fallacy can be elusive and oh-so-easy to fall into, if you’re not careful. Put simply, petitio principii occurs when one’s argument assumes the conclusion before it has been proven, or when an essential premise is assumed rather than stated. It may be done in one or multiple steps and is sometimes difficult to spot when synonyms are used. This sort of “argument” tends to go around in logical circles (ergo, “circular reasoning”). Instead of proving the conclusion, it continues to “beg the question”.

Example 1:

“Parents should not be allowed to homeschool, because only the government should be in charge of educating children.”

Example 2:

“Same-sex marriage should not be legalized, because men should only marry women and vice versa.”

In both of these examples, the conclusion is stated first, followed by a premise that is essentially another way of stating the conclusion. The “premise” doesn’t actually doesn’t give any more supportive information, so the conclusion remains unproven. Gonna need something more substantial to make either case.

Here’s a fun one…

cartoon of mad scientist / evil geniusExample 3:

“Of course Dr. Diabolicus is an evil genius! All of us acolytes agree that the guy is SUPER smart, and Diabolicus himself constantly and with fiendish glee reminds anyone within earshot of both his nefariousness and his ‘unmatched intellect’! He’s really smart, so, y’know, he oughtta know.”

I think you get the picture….

Note: It has become common to use the term “begs the question” to mean “raises the question” or some variation thereof. This is improper use of the term. Don’t do it. Bad. (Not evil/bad, just not a good idea. Trust me. ‘Cuz I said so.)

Complex question

This is a form of the “loaded question”. It makes or implies a conclusion of fact, based on some other, yet unproven, assumption. A simple ‘yes’ or ‘no’ answer doesn’t cut it without making the person being asked look bad, because responding either way seems to mean acceptance of the unproven assumption. Confused? OK, a couple examples should make it clear, and the classic example for this one is:

“Hey, Joe! Have you stopped beating your wife?”

The unproven assumption is that Joe does indeed have a history of spousal abuse, and either a ‘yes’ or ‘no’ implies an admission of guilt. If this was, say, said by one local politician to his rival, a fair response would be, “You know there’s no truth to those rumors, Ralph, because you started them. You must really be desperate to resort to that kind of slanderous mudslinging!”

Another might go like this:

“Are you creationists still making up facts and lying to your followers, so you can make a buck?”

This statement presumes that the subjects are liars and frauds, and a simple denial is insufficient, because the word “still” implies that they have been doing it for awhile. A better answer might be, “We may disagree with the interpretations of the evidence by many scientists, but, as far as I know, no creationist leaders have ever intentionally deceived anyone.”

See how that works? Good. You see how unfair it is and would probably hate to be on the receiving end, so I think we can all agree to try to keep such “arguments” out of our debates and discussions.

Samples’ recommendation for this week is…

LESSON: “Openly acknowledge and seek to fairly justify any worldview presuppositions, thus avoiding inappropriate presumption.”


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