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Write this proposition in the form of "if p, then q"

Mary will go swimming unless the water is too cold.

I will answer:

if the water is not too cold, then Mary will go swimming.

Is this correct btw?

David G. Stork
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Shou Yuman
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    I'd interpret it to mean "Mary will go swimming if and only if the water is not too cold", so I'm not sure the question itself can be answered since this cannot be put in the form "if $p$, then $q$". – Clive Newstead Dec 12 '18 at 13:40
  • "Understanding unless" ? Look here : https://philosophy.stackexchange.com/questions/14603/why-is-unless-considered-a-conditional-disjunction-rather-than-an-equivalence . No, it really is philosophical. – Sarvesh Ravichandran Iyer Dec 12 '18 at 13:48
  • Well honestly i kinda confuses when my lecturer said the answer is: If the water is too cold, then Mary will go swimming – Shou Yuman Dec 12 '18 at 14:33
  • You are right to be confused. Your proposed answer is the correct one : " If the water is not too cold, then Mary will go swimming". – Mauro ALLEGRANZA Dec 12 '18 at 15:00
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    '$P$ unless $Q$' is a bit tricky ... by it, we definitely mean that '$P$ is the case as long as $Q$ is not the case' ... which translates to $\neg Q \rightarrow P$ ... but sometimes we add to that 'but once $Q$ does become the case, then $P$ ceases to be the case .. which itself translates into $Q \rightarrow \neg P$, and so combined with the first part, you would get $\neg Q \leftrightarrow P$. So, when faced with an 'unless', the question is: can we assume that the stronger $\neg Q \leftrightarrow P$ is meant, or should we just stick to the weaker $\neg Q \rightarrow P$? – Bram28 Dec 12 '18 at 15:49
  • Your answer does not rule out the possibility that Mary will go swimming even if the water is too cold. To do so, your answer should be a biconditional. Then, if the water is too cold, Mary will NOT go swimming. – Dan Christensen Dec 14 '18 at 04:37

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