Return to Philosophy Web       Title: Introduction to Logic

Homepage > Logic > Informal Fallacies > Fallacies of Relevance > Petitio Principii Examples 


Logic Homepage




 Petitio Principii Examples Exercise

Abstract: Petitio principii examples are provided and analyzed for credibility.

Fallacy Practice Directions:

(1) Study the features of the petitio principii from this web page: Petitio Principii or Begging the Question.

(2) Read and analyze the following passages.

(3) Explain with a sentence or two as to whether or not you judge a petitio principii fallacy to be present.

  1. “Scientists have discovered the reason why plant foods offer such powerful cancer protection. Certain substances found only in plant foods are known collectively as phytonutrients (phyto is a Greek word meaning ‘plant’) have the ability to stop cancer.”[1]

  2. “[F]reedom is the freedom of choosing but not the freedom of not choosing. Not to choose is, in fact, to choose not to choose.”[2]

  3. “The symptoms of joint pain, however, correlate poorly with X-ray evidence of OA [osteoarthritis]. The reason behind this remains unclear, but it is likely that the pathological changes associated with joint OA and the symptoms of joint pain are not always visible on radiological imaging. The prevalence of joint pain is therefore likely to be far higher than the prevalence of radiographic evidence of OA.”[3]

  4. “Solon when he wept for his son's death, and one said to him, ‘Weeping will not help;’ answered, ‘Alas, therefore I weep, because weeping will not help.’”[4]

  5. “Ordinary common sense tells us ‘You cannot do what you cannot do‘ (i.e., you cannot do what, in fact, you are not capable of doing) … ”[5]

  6. “Dumbbell training is inherently safe. I've never observed a torn muscle or any other serious injury resulting from the proper use of dumbbells.”[6]

  7. “I think it's fair to say the media look down on Americans who embrace religion, gun rights and conservative values. So, media outlets demonize the tea party all day long, calling it racist, stupid and, worse, unsophisticated!”[7]

  8. “[I]t is a matter of curiosity walking as I do, for example right now on the Day of the Dead, because the Day of the Dead is something that greatly interests me. Every Day of the Dead is different from the one before and I wouldn't miss any Day of the Dead—why would I miss it, given I was interested in it?”[8]

  9. “I hate Michaelmas daises and, I must confess, I am not too keen on people either, in fact you might say I hate people too, or, better still, that I hate people as much as I hate Michaelmas daisies and that is simply because every time I see Michaelmas daisies they remind me of people rather than of Michaelmas daisies, and every time I see people I always think of Michaelmas daisies not of people.”[9]

  10. “Twice a year, in April and October, I remind you of the market's remarkable seasonality, the popular version of which is known as ’Sell in May and Go Away.’ It calls for getting out of the market on May 1 and getting back in on Nov. 1.

    “As with most investment strategies, most investors have only short-term thoughts regarding it … If it didn't work out the previous year then clearly it's either just a silly theory, or a strategy that may have worked in the past but the pattern has obviously come to an end.

    “And like all strategies … it doesn't work in every individual year. But it doesn't have to in order to produce remarkable outperformance over the long term. That's because in years when the market makes more gains in the unfavorable season when a seasonal investor is out, the seasonal investor doesn't have a loss, but merely misses out on additional gains. But when the market does have a correction in the unfavorable season, its losses can be well into double-digits which the seasonal investor avoids.”[10]

  11. “The news is fake because so much of the news is fake.”[11]

  12. Dilla: What a brain! And you know how to prove things, like the big shots?
    Emanu: Yeah, I have a special method for that. Ask me to prove something for you, something real hard.
    Dilla: All right, prove to me that giraffes go up in elevators.
    Emanu: Let's see. Giraffes go up in elevators … because they go up in elevators.
    Dilla: You're too much! … Suppose I asked you to prove giraffes don't go up in elevators.
    Emanu: That's easy. I just prove the same thing, but the other way around.”[12]

  13. “The soul is ... no more capable of ... being divided in itself, because it is not dissolvable. For if it were compounded it would be capable of dissolution, and if it were capable of dissolution it would not be immortal. Therefore, because it is not mortal it is neither dissolvable nor divisible.”[13]

  14. “The elemental composition of Jupiter is known to be similar to the sun. … The core would be composed mainly of iron and silicates, the materials that make up most of the earth's bulk. Such a core is expected for cosmogonic reasons: If Jupiter's composition is similar to the sun's, then the planet should contain a small portion of those elements.”[14]

  15. “I'm turning 50 and I see things differently now. At 40, I was building a practice and doing lots of surgery because that's what I do. I am a physician first, who also does surgery. … Older and wiser, [I see] questions and issues that [I] had not seen as a younger physician.”[15]


1. Selene Yeager, et al. The Doctors Book of Healing Foods (Emmaus, Pennsylvania: Rodale Inc., 2008), 21.

2. Jean-Paul Sartre, Being and Nothingness trans. Hazel E. Barnes (New York: Philosophical Library, 1956), 481.

3. Chin Teck Ng and Maw Pin Tan, “Osteoarthritis and Falls in the Older Person,” Age and Ageing 42 no. 5 (Sept. 2013), 562.

4. Francis Bacon, Apaphthegms in The Works of Francis Bacon ed. Basil Montagu (Philadelphia: Parry & McMillan, 1859), 113.

5. Adapted from Donna Ford, Reversing Underachievement Among Gifted Black Students 2nd. ed. (Naperville, Illinois: Sourcebooks, 2010), 130.

6. Bill Phillips and Michael D'Orso, Body for Life (New York: HarperCollins, 1999), 123.

7. Bill O'Reilly, “Is the Party Over?,” Index-Journal 95 no. 177 (October 29, 2013), 6A.

8. László Krasznahorkai, “There Goes Balzer,” trans. Georges Szirtes London Review of Books 36 no. 6 (March 20 2014), 45.

9. László Krasznahorkai, “There Goes Balzer,” trans. Georges Szirtes London Review of Books 36 no. 6 (March 20 2014), 45.

10. Sy Harding, “'Tis the Season,” quoted in “ Market Watch” Barron's 92 No. 42 (October 15, 2012), M16.

11. Donald Trump, “Full Transcript Trump News Conference” (16 Feb 2017) (accessed 16 Feb 2017).

12. Fernando Arrabal, Automobile Graveyard (New York: Grove Press, 1960), 27.

13. Charles S. Stanford, “Opinions on the Immortality of the Soul" in his translation of Phædo by Plato (New York: William Gowans: 1854),148.

14. John H. Wolfe, “Jupiter,” Scientific American 230 no. 1, (Jan. 1974), 121.

15. Laurence A. Savett, The Human Side of Medicine (London: Auburn House, 2002), 151.



Send corrections or suggestions to larchie[at]
Read the disclaimer concerning this page.
      © 1997-2017 Licensed under GFDL

GNU General Public License

The “Copyleft” copyright assures the user the freedom to use, study, redistribute, and make modifications so long as that derivative works have the same or identical license.


Arguments | LanguageFallacies  | Propositions  | Syllogisms  | Translation  | Symbolic