# Converse? Inverse? Some kind of \*verse? **URL:** \ **Category:** Factual Questions\ **Created:** [November 1, 2010, 4:52pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099 "2010-11-01T16:52:25Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Malice](https://avatars.discourse-cdn.com/v4/letter/m/278dde/32.png) [@Malice](https://boards.straightdope.com/u/Malice)\ **Post date:** [November 1, 2010, 4:52pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/1 "2010-11-01T16:52:25Z")
“Doctors make the worst patients, but some believe the converse may also be true − that patients make the best doctors.” Is the second statement really the converse of the first if it switches “worst” to “best”? ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [November 1, 2010, 5:54pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/2 "2010-11-01T17:54:32Z")
Nope. It’s not really a good fit for that sort of analysis; if we state p: X is a good doctor, and q: X is a good patient, then we can say “if p, then not q”; the closest we can come to the second proposition is “if q, then p,” which doesn’t bear much relationship at all to the first. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [November 1, 2010, 7:24pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/3 "2010-11-01T19:24:20Z")
Premise: “If you have East Asian genes, your eyes exhibit the epicanthic fold.” (For purposes of this post, never mind whether it is a valid premise, a stereotype, or what.) Converse: “If your eyes have the epicanthic fold, you have East Asian genes.” Inverse: “If you do not have East Asian genes, your eyes do not have epicanthic folds.” Contrapositive: “If you do not have the epicanthic fold, then you do not have East Asian genes.” A premise and its contrapositive are logically related – if one is true, the other is true as well. Its inverse and converse are also logically related in the same way – each is the contrapositive of the other – and are not logically related to the original premise. ---
**Author:** ![Tyrrell\_McAllister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tyrrell_mcallister/32/16772_2.png) [@Tyrrell\_McAllister](https://boards.straightdope.com/u/Tyrrell_McAllister)\ **Post date:** [November 1, 2010, 7:32pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/4 "2010-11-01T19:32:19Z")
> [@Malice](#): > > “Doctors make the worst patients, but some believe the converse may also be true − that patients make the best doctors.” > > Is the second statement really the converse of the first if it switches “worst” to “best”? Strictly speaking, the converse would be “Non-doctors are not the worst patients.” So, to call “Patients make the best doctors” the converse is to assume tacitly that [ol] [li] to be a non-doctor is equivalent to being a patient, and[/li][li] to be a non-worst-patient is equivalent to being a best-doctor.[/li][/ol] ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [November 1, 2010, 7:43pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/5 "2010-11-01T19:43:31Z")
Another vote for: It’s not the converse, and the concept of “converse” doesn’t even really apply to that kind of statement. The converse of a conditional statement “If P then Q” would be “If Q then P.” So, you could say that the converse of “If a person is a doctor, they’re a bad patient” would be “If a person is a bad patient, they’re a doctor.” (I hope it’s obvious that the converse is not logically equivalent: just because a conditional statement is true doesn’t make its converse true.) The inverse of “If P then Q” would be “If not P then not Q.” So, you could say that the converse of “If a person is a doctor, they’re a bad patient” would be “If a person is not a doctor then they’re not a bad patient.” (This is not logically equivalent to the original statement, but it is logically equivalent to its converse.) ---
**Author:** ![Tyrrell\_McAllister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tyrrell_mcallister/32/16772_2.png) [@Tyrrell\_McAllister](https://boards.straightdope.com/u/Tyrrell_McAllister)\ **Post date:** [November 1, 2010, 7:48pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/6 "2010-11-01T19:48:55Z")
> [@Tyrrell\_McAllister](#): > > Strictly speaking, the converse would be “Non-doctors are not the worst patients.” Oops. What I gave isn’t _strictly speaking_ the converse. My statement just means the same thing as the converse. **Thudlow Boink** gave the actual converse. ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [November 1, 2010, 8:17pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/7 "2010-11-01T20:17:07Z")
In the early 1980s, I went to New Orleans. I guess it was the peak of the Urban Cowboy fad, and there were country & western beer halls with mechanical bulls in them. One was selling a bumper sticker, “If you ain’t a cowboy, you ain’t sh\_\_” At the time, I thought the converse might prove it, that is, “If you **are** a cowboy, you **are** sh\_\_.” Years later, I got to know some cowboys, and I know they aren’t. Now, would microbiologists make the best, or the worst sauerkraut? ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [November 1, 2010, 8:35pm UTC](https://boards.straightdope.com/t/converse-inverse-some-kind-of-verse/559099/8 "2010-11-01T20:35:44Z")
> [@Nametag](#): > > Nope. It’s not really a good fit for that sort of analysis; if we state p: X is a good doctor, and q: X is a good patient, then we can say “if p, then not q”; the closest we can come to the second proposition is “if q, then p,” which doesn’t bear much relationship at all to the first. The first claim has the form p ==\> ¬q. Its converse is ¬q ==\> p, which is equivalent to ¬p ==\> q. The second claim is that q ==\> p. So it is nothing like the converse. Maybe vice versa would describe it better..