How did “to wish that” come to hate the present tense in the subordinate clauses it governs, and why is it alone in this?

Question

_{Inspired by this earlier question, I've realized that we have no canonical question addressing the strangely one-of-a-kind special grammatical rules demanded by the verb wish of its subordinate clauses. This question seeks to remedy that situation.}

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How did the verb to wish that come to require unique grammatical rules unlike any other?

The verb wish has several related grammatical “quirks” when it comes to which tenses you are allowed to use (and not use) in any subordinate clauses it governs. Notice how with the verb think you can say either of

• I think I know. ✅
• She thinks he knows. ✅

perfectly well, yet when switching to the verb wish you find that suddenly you cannot say either of

• I wish I ^_❌know. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]
• She wishes he ^_❌knows. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]

This shows that the verb wish has “special grammatical rules” about what tense you can put its subordinate clause into, “rules” that no other verb in common use in present-day English must adhere to.

How come?

The first mystery

For one thing, wish abhors the present tense in its subordinate clause completely. These are both grammatically forbidden:

1. I wish that she ^_❌eats fish on Fridays. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]
2. I wish that she ^_❌eats fish tonight. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]

The second mystery

It’s not even too keen on the past tense, either, since although (1) becomes legal if you switch the subordinate clause’s present tense to the past:

3. I wish that she ate fish on Fridays. ✅

Attempting this same thing with the subordinate clause in (2) still leaves the result ungrammatical:

4. I wish that she ^_❌ate fish tonight. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]

Interestingly, (4) is even ungrammatical when we explicitly switch the referenced time to the past:

5. I wish that she ^_❌ate fish last night. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]

This is a further unexplained special restriction on the tense of the subordinate clause, but this time even the past tense is blocked! Why can the past tense not be used in the subordinate clauses of (4) and (5) to make those grammatical, but can be — and does so — in (3)? How are those different?

All this appears to be true for other present-tense incarnations of wish such as I have wished that. Then when you start moving into the past tense with I wished that and I had wished that, the rules change but even here its rules seem to remain peculiar to wish alone. (I leave those details for the answerers.)

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The puzzle to be solved

How in the world did such a common verb as wish ever come to have such uncommon — and apparently even unique — grammatical rules governing tense use in its subordinate clause’s verb?

Do any other verbs work in this special way? Did they ever? Is this something new or something old? Has it always worked this way in English even before the Conquest, or did we get it grafted onto us by the Norman French?

I’m especially looking for answers rooted in actual historical analysis, not “just because” handwaving that doesn’t address the construction’s history. You don’t have to go back to PIE (unless you want to :), but I’d like for us to have answers whose explanations at least require looking at this curiosity’s historical evolution.

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References

The OED gives as sense 1a of the verb wish::

1. a. transitive. To have or feel a wish for; to desire.

^{The ordinary word for this; now always less emphatic than the synonyms covet, crave, long (for), yearn (for); in earlier use occasionally in the sense of these. Sometimes softened by could or should (would): cf. ᴄᴀɴ *v.*¹ 17, ꜱʜᴀʟʟ v. 19c, ᴡɪʟʟ *v.*¹ 40c; or strengthened before a subordinate clause (1b, 2c) by such phrases as to God, to goodness, to heaven.}

• (a) with simple object (in Old English usually in the genitive). Now dialect; superseded in standard English by wish for (see 2), or colloquial in certain contexts by want (ᴡᴀɴᴛ v. 10).

• (b) with object clause with may or (formerly) present subjunctive, occasionally indicative: expressing a desire that the event may happen or that the fact may prove to be so, and often implying some want of confidence or fear of the opposite (now commonly expressed by hope: see ʜᴏᴘᴇ v. 3b). Also expressing a request (see 5).

• (c) with object clause with past subjunctive (or indicative, e.g. was for were): expressing an unrealized or unrealizable desire (see also ᴡɪʟʟ *v.*¹ 46a), or in modern use sometimes a mild request (cf. 5). to wish to God: to wish intensely.

Here are just a few citations from sense 1a(c). The non-present-tense verbs in the subordinate clauses I have marked in bold.

• c1000 Ælfric Deut. xxxii. 29
  Ic wisce ðæt hi wiston & undergeaton..hyra ende [L. utinam saperent].

• 1362 Langland Piers Plowman A. v. 92
  Þenne I wussche hit weore myn.
• c1385 Chaucer Legend Good Women Thisbe. 755
  Thys wall they woldyn threte And wysshe to god hyt were doun ybete.
• a1616 Shakespeare Macbeth (1623) ɪ. v. 24
  That which rather thou do'st feare to doe, Then wishest should be vndone.
• 1817 Byron Let. 25 Mar. (1976) V. 188
  Heigh ho! I wish I was drunk—but I have nothing but this d—d barley-water before me.
• 1832 Tennyson New Year's Eve iv, in Poems (new ed.) 96
  I wish the snow would melt..I long to see a flower so.

Swapping in the present indicative there produces ungrammatical sentences the likes of which neither Chaucer nor Shakespeare, nor Byron or Tennyson, could ever have generated:

• ...And wish to God she ^_❌is done beaten.
• That which rather thou dost fear to do, then wishest ^_❌is undone.
• ...I wish I ^_❌am drunk.
• ...I wish the snow ^_❌melts.

Those are just as ungrammatical now as they were then. No other surviving present-ense verb still forbids the present indicative in its subordinate clause.

Sense 5 seems close to this, and also has citations showing the avoidance of the present indicative:

5. In expressions of desire for something to be done by another, thus conveying a request; hence, to request, entreat; formerly sometimes, to bid, command:

• a. a thing or action (with various const. as in 1): cf. ᴅᴇꜱɪʀᴇ v. 5.

1875 B. Jowett tr. Plato Dialogues (ed. 2) I. 429
I wish that you would tell me about his death.

There’s also a much older, sixteenth-century citation that when rendered into modern spelling runs:

I wish rather and desire that in hope of bairns he take Margaret rather than Magdalen for his bedfellow.

That isn’t the same as the earlier examples involving would because here it takes a bare infinitive without a modal in what is sometimes called the “mandative subjunctive”, which is where a verb like demand, desire, require takes a subordinate clause whose verb is today in the bare infinitive (and used to be in the present subjunctive).

Answer 1

You asked quite a few questions. Here is an attempt at providing answers to a portion of them.

1. Is this something new or something old? Has it always worked this way in English even before the Conquest, or did we get it grafted onto us by the Norman French?

I am surprised you passed without comment OED's sense 1a(b) [with object clause with may or (formerly) present subjunctive, occasionally indicative], which is now pretty much obsolete but which includes such old but attested examples as I wish I suffer no prejudice by it (1661), I wish the house is not rob'd (1691), He is certainly bewitched: I wish the old hag upon the green has done him no mischief (1756), I wish we have not got King Stork, instead of King Log (1823). That's your answer to this particular set of questions: the highly specialized behavior of wish is relatively new. As recently as the first half of the 19th century, wish could take as complement a content clause in the present subjunctive or even indicative.

2. The first and second mystery.

I interpret these as asking what is the actual rule that can predict what sorts of finite complements to wish result in acceptable sentences.

As I said in the comments, and as others stated in their answers (a few said this after I did, though now I see that some have also said this before I did), the answer is that a finite complement of wish must convey modal remoteness. Grammatically, this means that a finite clause complement of wish must use ether the modal preterite or else the irrealis were (the latter is what some sources call the past subjunctive, but CGEL has an argument against that analysis, pp. 87-88). This is pretty much what CGEL says in various places. Thus, for instance, we need I wish she had eaten fish last night. In CGEL, the example [29iv] on p. 1003, ^#I wish [you passed your driving-test tomorrow], is marked (by the '#') as 'semantically or pragmatically anomalous'. CGEL says that

wish cannot be used with a 'pure' future, one where there is no present time involved: cases like this are still within the realm of hoping, so that instead of [iv] we would say I hope you pass your driving-test tomorrow.

3. Do any other verbs work in this special way?

Arguably, no. You can rephrase this as the following questions: 1. in what sorts of constructions do we find modal preterite and irrealis content clauses? 2. Are there any verbs other than wish that appear (when taking a finite clause complement) only in such constructions?

CGEL lists four kinds of constructions where we find modal preterite and irrealis content clauses (pp. 1003-1004): (a) remote conditionals, (b) complement to wish, (c) would rather/sooner/as soon (also prefer, as a marginal possibility), and (d) it be time. However, (c) allows the subjunctive (I'd rather it be sooner (source)), while (d) allows both the subjunctive (it is time he see that he has earned that right (source), it is time he submit his letter on no confidence (source)) and the present tense (It is time he enters into the twenty-first century or disappears. (source)); see also here. True, even in (c) and (d), the subjunctive and/or the present tense are much less frequently used than the modal preterite and irrealis, but they are nevertheless used at least sometimes. Thus, none of the other possibilities are as specialized as wish when it comes to what kind of finite-clause complements they can take.

Answer 2

TaliesinMerlin's answer seems to be the bee's knees ("business"). No etymological-historical answers here (sorry), no bounty sought. Just deeply intrigued by this verb, for the first time in my life, now you draw attention to its oddity.

Similarity to reported speech

What about this:
he said he ate fish on fridays / he said he eats fish on fridays
he said he had eaten fish yesterday / he said he ate fish yesterday
he said he would eat fish tonight / he said he will eat fish tonight

What is the name (if any) given to the mood of this "backshifted" content phrase in the first parts of these pairs? Could it be inferential? The wish construction is very similar to reported speech... but with wish it is mandatory to use the backshifted version.

Difference to reported speech

Reported speech introduces a note of doubt: just because "he said X" doesn't mean X is true.

"I wish that she would eat fish tonight", I suggest, along with the "ate" and "had eaten" versions, involves a different type of mood.

I had suggested the desiderative mood, or possibly the hortative mood (for phrases such as "I wish you would eat fish tonight"), but after reading TaliesinMerlin's answer the most likely suggestion for most cases appears to be the optative mood.

Which came first?

I.e. between reported speech and the wish construction. Is it possible that this modern wish that construction modelled itself on reported speech? Or the other way round? No idea.

TaliesinMerlin also says that these are probably "cousin constructions" which developed in parallel. This is interesting if so, since the reported speech version, by its nature, allows indicative in the content clause, or something other than indicative. Whereas the wish version abhors the indicative: only the optative (or hortative) is permitted, but other than that they mirror one another quite strikingly. It seems that our ancestors' linguistic sense knew that it was imperative for wishing to be expressed with a substitute irrealis mood of some kind as the true grammatical subjunctive fell into decline. Could we say that this construction is therefore in some sense a living fossil, or testimony to the resilience of "subjunctive feeling" in English?

When?

Also refer to TaliesinMerlin's authoritative answer for when these constructions may have entered the language, and how: 16th, 17th centuries or so... but not a neat transition, as he/she says.

Answer 3

This answer will describe the historical context for the verb to wish and what forms the main verb in the subordinate clause following wish can take.

Indo European, Greek, and Latin

First, Indo European languages sometimes use one of two moods to indicate a wish. (Reminder: verbal moods indicate the speaker’s intent or attitude; common moods include the indicative, the imperative, and the subjunctive.) The first is optative mood, which indicates a wish or hope. This is one of four moods that likely came from Proto-Indo-European. It is present in Ancient Greek; one gives a wish or a hope by putting the appropriate suffix on the verb, and sometimes an additional particle (adverb-like item), εἴθε, (eithe) which is glossed “would that!” (Perseus Tufts). Latin (among other languages) folds the same function into the subjunctive mood, and often accompanies its wishes with utinam (again “would that” or “if only) (Perseus Tufts) (The Latin Library).

In Latin, the verb opto (I wish) was often used to set up a subordinate clause, headed by ut, that would indicate what was wished for. The verb within the subordinate clause would take the subjunctive case or the infinitive, resembling the optative subjunctive (examples from Perseus Tufts):

(Phaëthon) optavit, ut in currum patris tolleretur,” Cic. Off. 3, 25, 94

(He wished that he were carried up in his father’s chariot) (tolleretur is in the passive imperfect subjunctive)

optavi, peteres caelestia sidera tarde,” Ov. Tr. 2, 57.

(I wished that you reached the heavenly stars late (peteres is in the active imperfect subjunctive)

“hunc videre saepe optabamus diem,” Ter. Hec. 4, 4, 29

(We often wished to see this day) (videre is in the infinitive)

The verb volo (I wish, will, want) works similarly (Perseus Tufts), as do a few other verbs of wishing, desiring, and fearing. If the verb in the subordinate clause is in the subjunctive, it will tend to be in imperfect tense (translated to past tense in English). These rules tend to be covered under either the “optative subjunctive” or the “substantival clause of purpose”; in general, expect the subjunctive, which means expecting either a past or present tense.

So even outside of English, languages have rules that are specific to wishing (the optative subjunctive) and rules that tend to govern subordinate clauses (when in a subordinate clause of purpose, use the subjunctive). So it should be little surprise that wishing works similarly in Old English.

Old English and Onward

Old English has a subjunctive and it has verbs of wishing. The Old English subjunctive is odd because there is no distinct first, second, or third person form. So for bēon (to be), the past subjunctive is wǣre in the singular and wǣren in the plural, and the present subjunctive has two forms, bēo and sīe (with –n in the plural) (Introduction to Old English by Peter S. Baker, p.67). The book notes that the subjunctive is used in clauses following verbs of desiring and commanding (p.85):

Ic wysce þæt ic wisra wære

(I wish that I were wiser) (waere is in the past subjunctive)

To compare to a similar situation, the subjunctive can also be used in indirect discourse:

Hie cwædon þæt he wære wis.

He said that he was wise. (waere is still subjunctive; “he said that he were wise” feels unusual in Modern English)

However, in a situation like indirect discourse, the indicative can also be used:

Be him awrat se witega Isaias þæt he is stefn clipiendes on westene.

Concerning him, the prophet Isaiah wrote that he is the voice of one crying in the wilderness (is is in the indicative)

Wish remains locked into the subjunctive in Old English, which only evolves into periphrastic or indicative uses over time. This is reflected in entries 1a, 1b, and 1c in the Oxford English Dictionary. I requote 1b and 1c as the most relevant:

(b) with object clause with may or (formerly) present subjunctive, occasionally indicative: expressing a desire that the event may happen or that the fact may prove to be so, and often implying some want of confidence or fear of the opposite (now commonly expressed by hope: see hope v. 3b). Also expressing a request (see 5).

(c) with object clause with past subjunctive (or indicative, e.g. was for were): expressing an unrealized or unrealizable desire (see also will v.1 46a), or in modern use sometimes a mild request (cf. 5). to wish to God: to wish intensely.

Both entries show that, over time, the use of the subjunctive decayed and was replaced by the indicative or by the use of periphrastic constructions using verbs like may or would:

(subjunctive weore) 1362 Langland Piers Plowman A. v. 92 Þenne I wussche hit weore myn.

(indicative had never known) a1561 G. Cavendish Metrical Visions (1980) 539 Therfor my frayltie I may bothe Curse and ban. Whissyng to God I had neuer knowen man.

(subjunctive were) 1578 J. Lyly Euphues f. 31 I wish my wish were as effectually ended as it is heartely looked for.

(construction with would) 1625 J. Ussher Let. in R. Parr Life J. Usher (1686) Coll. lxxiv. 315 I could wish that Mr. Lisle would take some pains in translating the Saxon Annals into our English Tongue.

The transition isn’t neat though, with the 16th and 17th centuries featuring a lot of periphrastic, subjunctive, and indicative examples in subordinate clauses following wish.

Meanwhile, 1d and 1e support the use of the infinitive after about the 14th century, and continuing thereafter. Here is one example:

c1560 A. Scott Poems (S.T.S.) xv. 39 Away I went,..Wissing all luvaris leill to haif sic chance.

All of this corresponds to the general decline of the subjunctive mood in English and the growth of other options to replace it. Middle English (a) lost verb endings and hence features that would have distinguished the subjunctive, (b) fostered periphrastic constructions with sholde, shal, wil, may, and can), (c) used the past tense indicative as a substitute for the subjunctive, as a modal preterite. These changes continued into early modern English to the present day (Eva Kovacs, “On the Development of the Subjunctive from Early Modern English to Present-Day English, p. 82).

Concluding the Mysteries

What you’re observing with wish are the trace elements of the old subjunctive system, where periphrastic constructions, past-tense verbs (substitutes for the subjunctive), or sometimes the infinitive are far more often permitted than present-tense verbs.

So for the first mystery, the present tense indicative would have always been avoided, first with the subjunctive and then with its replacements:

(x) I wish that she eats fish on Fridays.

I wish that she ate fish on Fridays. (Subjunctive-ish past tense or preterite)

I wish that she eat fish on Fridays. (Bare infinitive)

I wish that she would eat fish on Fridays. (Periphrastic modal in present)

For the second mystery, the past tense indicative would also be avoided if its subjunctive and indicative use became too ambiguous. In your example, you shift from speaking about a repetitive action (eating fish on Fridays) to a single moment in the past. In the history of English, one way to disambiguate a subjunctive sense is to go to a past indicative form. Because the verb is already in the past, taking another step into the past would lead to a periphrastic past perfect form. The periphrastic constructions appropriately conveys both tense and mood:

(x) I wish that she ate fish last night.

(x) I wish that she eat fish last night.

(x) I wish that she would eat fish last night.

I wish that she had eaten fish last night. (Periphrastic past perfect)

I wish that she would have eaten fish last night. (Periphrastic modal in past)

Answer 4

I doubt it's anything exciting in the history of this word. Wish generally govern the modal preterite in its subordinate clause complement. That seems unusually, but it's not at all surprising given the lexical semantics. The interesting historical aspect will probably lie mostly in the semantics and syntax of related constructions.

As for the first mystery, wish requires that the inflected verb in its subordinate clause be in preterite form: though not to indicate past time, rather for modal remoteness. Note that when you say, standing in front of a locked safe:

I wish I knew the combination!

...you are not referring to some prior state of knowledge. It is that at the time of speaking the unrealized possibility of you knowing the combination is relevant.

If you want to indicate past time in the subordinate clause, the best you can do is use a perfective construction:

I wish I had known the combination.

So the issue of past vs. present is a red herring. As you see above, both past and present time cna be marked in wish-sentences, but the main tense marking system is not available because it's captive to its (normally secondary) modality-marking function.

One other thing to note: to get future time in wish-sentences you have to have the auxiliary will in its modal preterite form as well:

I wish she would eat fish next week.

As for the second mystery, you are coercing the tense-marking function of the preterite form with the temporal adjuncts, which is why you have the ungrammaticality. As noted above, you can signal past time well enough with a perfect construction:

I wish she had eaten fish last night.

Is wish all that special? I don't think so. It's just one of few verbs whose semantics specifically point to a specific shade of unrealized, uncertain, unlikely possibilities. Verbs like pray, hope, expect don't have the same argument structure, but also have different semantics. The closest one I can think of is regret. You would probably have the most fruitful search looking at the development of the modal preterite specifically. You'll find some interesting things under "English modal preterite" on Google Scholar.

Answer 5

Your question is based on an incorrect analysis of the situation that mistakes the subjunctive for the past tense.

For one thing, wish abhors the present tense in its subordinate clause completely. These are both grammatically forbidden:
I wish that she ❌eats fish on Fridays. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]

It is perfectly valid to use the present tense with "wish". For instance, "I wish that she ate fish on Fridays." would be grammatical. This is not past tense, it is subjunctive (it is the past subjunctive, but "past subjunctive" simply refers to the subjunctive that takes the same form as the past tense, not a subjunctive that indicates past tense). For most verbs, the past subjunctive is the same as the past tense, but we can distinguish them with the verb "be", which has "was" as the past tense for singular third person, but "were" for past subjunctive singular third: "I wish that she were eating fish on Fridays." not "I wish that she was eating fish on Fridays."

since although (1) becomes legal if you switch the subordinate clause’s present tense to the past:
I wish that she ate fish on Fridays. ✅

That's not the past, that's the subjunctive.

It’s not even too keen on the past tense, either,
...
Attempting this same thing with the subordinate clause in (2) still leaves the result ungrammatical:
I wish that she ❌ate fish tonight. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ]

Again, it's not the tense, it's the mood. Indicative is not allowed, present or past. For the past tense, we need "I wish she had eaten fish tonight" (although it would be odd to speak of "tonight" as the past, since "tonight" means "the night portion of the current day", and night is the last part of the day, so "tonight" is pretty much always the present or future).

How in the world did such a common verb as wish ever come to have such uncommon — and apparently even unique — grammatical rules governing tense use in its subordinate clause’s verb?
Do any other verbs work in this special way?

Since "wish" introduces discussions of counterfactuals, it demands the subjunctive. There are other verbs that, at least in standard American English, also demand the subjunctive. For instance, "suggest" can mean "provide a suggested course of action" or "imply". In the first sense, subjunctive is demanded, and the indicative means that it is being used in the second sense: "I suggested he took the job" versus "I suggested he take the job". "Demand" also requires the subjunctive. The only thing unusual about "wish" is that it takes the past subjunctive. The reason for this is that while "suggest", "demand", and "hope" all refer to things that could happen, "wish" refers to things that definitely aren't the case. "Imagine" also requires past subjunctive when followed by a verb used as a verb: "Imagine she were here", but can also take a participle: "Imagine her being here".

Answer 6

This is not going to be an answer discussing the history of the verb 'wish'. But I hope (not "wish"❗) that this will be a good enough answer to your question.

To answer your question about the verb 'wish' requiring unique grammatical rules, it should be noted that you have another verb 'hope', which can fill the gap created by the verb 'wish'. That is, the verbs 'wish' and 'hope' are used for mutually exclusive contexts.

You cannot use 'wish' in the following sentences, because that's what 'hope' is for:

I wish I ❌know. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ] (I hope I know. ✅)

She wishes he ❌knows. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ] (She hopes he knows. ✅)

The first mystery is also easily understood when you take note of the existence of 'hope':

1. I wish that she ❌eats fish on Fridays. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ] (I hope that she eats fish on Fridays. ✅)

2. I wish that she ❌eats fish tonight. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ] (I hope that she eats fish tonight. ✅)

So is the second mystery:

4. I wish that she ❌ate fish tonight. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ] (I hope that she eats fish tonight. ✅) [This is what CGEL calls a 'pure future'.]

5. I wish that she ❌ate fish last night. [ ᴜɴɢʀᴀᴍᴍᴀᴛɪᴄᴀʟ❗ ] (I hope that she ate fish last night. ✅)

Now turning to "The puzzle to be solved":

How in the world did such a common verb as wish ever come to have such uncommon — and apparently even unique — grammatical rules governing tense use in its subordinate clause’s verb?

Because you have two common verbs 'wish' and 'hope', each assigned to deal with their respective mutually exclusive context. So if you just look at the verb 'wish', it might come across as "having uncommon and unique grammatical rules governing tense use in its subordinate clause’s verb", but if you look at both 'wish' and 'hope', the grammatical rules of 'wish' can be easily understood, because the two verbs are complementing each other in their respective grammatical role.

Do any other verbs work in this special way?

I think 'hope' can be viewed as "having uncommon and unique grammatical rules governing tense use in its subordinate clause’s verb" in that it cannot govern a that-clause expressing a "modal remoteness":

3. I wish that she ate fish on Fridays. ✅ ("I hope that she ate fish on Fridays." ✅ cannot convey a "modal remoteness" but can only describe a past event.)

EDIT

In case it's not clear what the mutually exclusive contexts are, 'wish' can only govern that-clauses expressing modal remoteness, whereas 'hope' can only govern that-clauses not expressing modal remoteness. So when a context is given, the two verbs cannot be interchanged. It should be either 'wish' or 'hope.'

Answer 7

I'm going to take a different approach to analyse the examples you list in example 1 and 2 as grammatical, therefore questioning the general premise whether the verb wish is restricting the tense in the that-clause. Maybe the verb 'wish' isn't that special? This is the reason why I flagged your question as a possible duplicate of "Is backshifitng optional?"

I'm going to cite an answer from a previous question:

NOTE: There's a common misconception that a present-tense verb being used in its timeless sense (or other related uses) cannot be backshifted. That is untrue, as backshifting is still generally available. For instance, in the older 1985 reference grammar by Quirk et al., A Comprehensive Grammar of the English Language, section 14.31, page 1027:

Here are other examples where present forms may be retained in indirect speech:

Their teacher had told them that the earth moves around the sun. -- [11] . . .

In all these sentences, past forms may also be used, by optional application of the backshift rule. Sentence [11] has the simple present in its timeless use, . . .

And so, according to Quirk et al., the following backshifted version (to correspond to [11]) is also acceptable:

Their teacher had told them that the earth moved around the sun.

Source: Using past tense when referencing a still-true fact

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I would also like to cite another user's comment:

Since, besides the history, you also wish to know what the current actual rules are: CGEL says that a finite complement of wish must convey modal remoteness. Thus, for instance, we need I wish she had eaten fish last night. In CGEL, [iv] #I wish [you passed your driving-test tomorrow] is marked as 'semantically or pragmatically anomalous'; they say that ' wish cannot be used with a 'pure' future, one where there is no present time involved: cases like this are still within the realm of hoping, so that instead of [iv] we would say I hope you pass your driving-test tomorrow.' – linguisticturn

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Your examples:

1. I wish that she eats fish on Fridays. *
2. I wish that she ate fish on Fridays. ?

are grammatically similar to the above examples, and can be questioned through modal remoteness. It is therefore important to note one thing: Context. Context. Context., before saying something is ungrammatical.

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What my previous answer was arguing for (in the comments):

It seems that whether something is grammatical, depends on what the counterfactual material is showing about modal remoteness, making back-shifting optional depending on the desired meaning:

(1) I wish that she eats fish | on Fridays

may sound ungrammatical, but it can also be parsed as:

(2) I wish that she eats fish | " insert phrase here "

i) my argument is that wish doesn't restrict the tense in the sentence at all, it is expressing a modal remoteness of a habitual occurrence as there is no 'on Fridays' so the intended meaning of 'I wish she eats fish' is until a set time in the future which is not directly expressed.

I wish that she eats fish is grammatical because it follows the same grammatical structure of some examples I will list and explain later (it is also grammatically similar to the example with the verb told and the verbs, moves/moved, pointed out in the answer earlier):

(2) I wish that she eats fish

= as mentioned before into the possible future and beyond.

But the assumption is that "she" does not like fish regardless of whether, to the best of their knowledge, it is true that she has tasted fish before or not.

(3) I wish that she ate fish

= an assumption that "she" has tried fish and does not like it at all; a choice. The subject is wishing that she did.

c.f. (2) and (3) with the below:

(4) I didn't know he had a son

and

(5) I didn't know he has a son.

Now:

(6) I wish that she eats fish | 'on Fridays'

is grammatical too because of example 2 with the sense I have given it in (i) .. but the wording is just awkward. It semantically conflicts, but if we change 'on Fridays' with another phrase, it would be grammatically and semantically valid:

(7) I wish that she eats fish | in the future

How do we know (7) is grammatically correct? Because the same problem poses in (9):

(8) I wish that she ate fish | on Fridays ?

(9) I wish that she ate fish | in the future

There is nothing grammatically wrong with (7) or (9) because of the sense I applied in (i) to mean in (7): I wish that she eats fish in the future* or I wish that she eats fish. There is, however, a subtle difference in nuance between (7) and (9) (excluding, everything after | ); the nuance in meaning is described in (2) and (3).

If I were to take other examples such as:

(10) I didn't know that she has a son

= implying that he is still alive.

(11) I didn't know that she had a son

= implying that he died or that they did not know this person had a son at all

(10) and (11) are perfectly grammatical because of their sense. I will then add something onto (10):

(12) I didn't know that she has a son | until tomorrow*

(12) means something along the lines of 'I didn't know she will have a son, until tomorrow' or potentially 'I didn't know she will have a boy, until tomorrow' (the gender of the baby won't be disclosed to me until he is born...);

(13) I didn't know that she had a son | until tomorrow

(13) is also semantically awkward because the verb had implies, the son had already been born, but the until tomorrow suggests the act of knowing happens in the immediate future and not in the immediate present, and hence (14). Perhaps, it would make much more sense if it were:

(14) I didn't know that she had a son | until today

(14) means that the subject did not know that "she" had a son at all (and hence already born, in the immediate past), until today, or it could mean the subject did not know that the "she had a son" in the immediate present, until today (at a later time, of course e.g. if the baby was born in the morning and the the act of knowing was realised for the subject later in the day: "I didn't know she had a son until today at work! Samantha told me").

*if you think (12) is ungrammatical, it's not, semantically awkward perhaps, but it allows for constructions such such as "I didn't know that she has a son | until ..." and "I didn't know that she had a son | until ...".

Notice how the verb had/has adds to modal remoteness but so does everything after | , we already know (12), (13), and (14) are grammatically valid because of (10) and (11).