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Forrester's paradox

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Forrester's paradox, also known as the paradox of gentle murder, is a paradox of deontic logic attributed to James Forrester.[1][2][3] It is a version of the Good Samaritan paradox.

Forrester's argument is that, starting from the statements that

  • It is obligatory (under the law) that Smith not murder Jones.
  • It is obligatory that, if Smith murders Jones, Smith murder Jones gently.

it logically follows that:

  • If Smith murders Jones, it is obligatory, that Smith murder Jones gently.

However, if it were actually the case that Smith murdered Jones, it can then be deduced that:

  • It is obligatory, that Smith murder Jones

which contradicts the first statement, leading to a logical fallacy.[4]

A number of arguments have been advanced that Forrester's paradox is invalid, for example that it is the result of a confusion of scope,[1][5] or a misuse of deduction rules.[6]

References

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  1. ^ a b Sinnott-Armstrong, Walter (1959). "A solution to Forrester's paradox of gentle murder". Journal of Philosophy. 56 (2): 162–168. doi:10.5840/jphil195956233. ISSN 0022-362X.
  2. ^ Goble, Lou (1991). "Murder Most Gentle: The Paradox Deepens". Philosophical Studies. 64 (2): 217–227. doi:10.1007/BF00404830. ISSN 0031-8116. JSTOR 4320256. S2CID 170715161.
  3. ^ Meyer, J.-J.Ch. (1987). "A simple solution to the "deepest" paradox in deontic logic". Logique et Analyse. 30 (117/118): 81–90. ISSN 0024-5836. JSTOR 44084186.
  4. ^ Forrester, James William (1984). "Gentle Murder, or the Adverbial Samaritan". The Journal of Philosophy. 81 (4): 193–197. doi:10.2307/2026120. ISSN 0022-362X. JSTOR 2026120.
  5. ^ Clark, Romane (1986-08-01). "Murderers are not obliged to murder; another solution to Forrester's paradox". Philosophical Papers. 15 (1): 51–57. doi:10.1080/05568648609506248. ISSN 0556-8641.
  6. ^ Peterson, Clayton; Marquis, Jean-Pierre (2012-10-01). "A Note on Forrester's Paradox". Polish Journal of Philosophy. 6 (2): 53–70. doi:10.5840/pjphil20126213.