Cherry picking

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For other uses, see Cherry picking (disambiguation).
Cherry picking can be found in many logical fallacies.

Cherry picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position, while ignoring a significant portion of related cases or data that may contradict that position. It is a kind of fallacy of selective attention, the most common example of which is the confirmation bias.[1][2] Cherry picking may be committed intentionally or unintentionally. This fallacy is a major problem in public debate.[3]

The term is based on the perceived process of harvesting fruit, such as cherries. The picker would be expected to only select the ripest and healthiest fruits. An observer who only sees the selected fruit may thus wrongly conclude that most, or even all, of the fruit is in such good condition. This can also give a false impression of the quality of the fruit (since it is only a sample and is not a representative sample).

A concept sometimes confused with cherry picking is the idea of gathering only the fruit that is easy to harvest, while ignoring other fruit that is higher up on the tree and thus more difficult to obtain (see low-hanging fruit).

Cherry picking can be found in many logical fallacies. For example, the "fallacy of anecdotal evidence" tends to overlook large amounts of data in favor of that known personally, "selective use of evidence" rejects material unfavorable to an argument, while a false dichotomy picks only two options when more are available. Cherry picking can refer to the selection of data or data sets so a study or survey will give desired, predictable results which may be misleading or even completely contrary to reality.[4]

In science[edit]

Choosing to make selective choices among competing evidence, so as to emphasize those results that support a given position, while ignoring or dismissing any findings that do not support it, is a practice known as "cherry picking" and is a hallmark of poor science or pseudo-science.[5]

— Richard Somerville, Testimony before the US House of Representatives Committee on Energy and Commerce Subcommittee on Energy and Power, March 8, 2011.

Rigorous science looks at all the evidence (rather than cherry picking only favorable evidence), controls for variables as to identify what is actually working, uses blinded observations so as to minimize the effects of bias, and uses internally consistent logic."[6]

— Steven Novella, "A Skeptic In Oz", April 26, 2011

In medicine[edit]

In a 2002 study, researchers "reviewed 31 antidepressant efficacy trials to identify the primary exclusion criteria used in determining eligibility for participation. Their findings suggest that patients in current antidepressant trials represent only a minority of patients treated in routine clinical practice for depression. Excluding potential clinical trial subjects with certain profiles means that the ability to generalize the results of antidepressant efficacy trials lacks empirical support, according to the authors."[7]

In argumentation[edit]

In argumentation, the practice of "quote mining" is a form of cherry picking,[5] in which the debater selectively picks some quotes supporting a position (or exaggerating an opposing position) while ignoring those that moderate the original quote or put it into a different context.

One-sided argument[edit]

A one-sided argument (also known as card stacking, stacking the deck, ignoring the counterevidence, slanting, and suppressed evidence)[8] is an informal fallacy that occurs when only the reasons supporting a proposition are supplied, while all reasons opposing it are omitted.

Peter Suber has written: "The one-sidedness fallacy does not make an argument invalid. It may not even make the argument unsound. The fallacy consists in persuading readers, and perhaps ourselves, that we have said enough to tilt the scale of evidence and therefore enough to justify a judgment. If we have been one-sided, though, then we haven't yet said enough to justify a judgment. The arguments on the other side may be stronger than our own. We won't know until we examine them. So the one-sidedness fallacy doesn't mean that your premises are false or irrelevant, only that they are incomplete."[9]

"With rational messages, you need to decide if you want to use a one-sided argument or a two-sided argument. A one-sided argument only presents the pro side of the argument, while a two-sided argument presents both sides. Which one you use will depend on which one meets your needs and the type of audience. Generally, one-sided arguments are better with audiences already favorable to your message. Two-sided arguments are best with audiences who are opposed to your argument, are better educated or have already been exposed to counter arguments."[9]

See also[edit]

References[edit]

  1. ^ The Internet Encyclopedia of Philosophy, "Fallacies", Bradley Dowden (2010)
  2. ^ Cherry Picking
  3. ^ Klass, Gary. "Just Plain Data Analysis: Common Statistical Fallacies in Analyses of Social Indicator Data. Department of Politics and Government, Illinois State University" (PDF). statlit.org. ~2008. Retrieved March 25, 2014. 
  4. ^ Goldacre, Ben (2008). Bad Science. HarperCollins Publishers. pp. 97–99. ISBN 978-0-00-728319-4. 
  5. ^ a b "Devious deception in displaying data: Cherry picking", Science or Not, April 3, 2012, retrieved 16 February 2015
  6. ^ Novella, Steven (26 April 2011). "A Skeptic In Oz". Science-Based Medicine. Retrieved 16 February 2015. 
  7. ^ "Typical Depression Patients Excluded from Drug Trials; exclusion criteria: is it "cherry picking"?". The Brown University Psychopharmacology Update. Wiley Periodicals. 13 (5): 1–3. May 2002. ISSN 1068-5308.  Based on the studies:
    • Posternak, MA; Zimmerman, M; Keitner, GI; Miller, IW (February 2002). "A reevaluation of the exclusion criteria used in antidepressant efficacy trials". The American Journal of Psychiatry. 159 (2): 191–200. doi:10.1176/appi.ajp.159.2.191. PMID 11823258. 
    • Zimmerman, M; Mattia, JI; Posternak, MA (March 2002). "Are subjects in pharmacological treatment trials of depression representative of patients in routine clinical practice?". The American Journal of Psychiatry. 159 (3): 469–73. doi:10.1176/appi.ajp.159.3.469. PMID 11870014. 
  8. ^ "One-Sidedness - The Fallacy Files". Retrieved 14 October 2014. 
  9. ^ a b Peter Suber. "The One-Sidedness Fallacy". Retrieved 25 September 2012. 

External links[edit]