This might just be availability bias on my part, but it seems to me that if a verb ends is a "d" sound then it's a lot more likely to have an irregular past tense than an average verb picked out at random. Examples include "feed/fed", "stand/stood", "rend/rent", "tread/trod", "betide/betid".
So, is this an actual pattern, or am I just imagining it?
And if it is a real pattern, what's the explanation?
Preserved from comments to the question:
It's related to the rule that we cannot have geminate consonants in English - so we cannot add the past tense morpheme /d/ onto a base that already ends with a /d/ (or /t/). So for example we cannot make the word /endd/ as a past form of the verb END. Usually, for most verbs we add an epenthetic vowel (so for the past form of END we get ended, /endɪd/). However, a different strategy is to reduce the final consonant, so for example instead of /bɪdd/ for the past of bid we can have either /bɪd/ with the double /dd/ reduced or /bɪdɪd/. – Araucaria
A different strategy is to use devoicing as well as consonant reduction 'build' --> 'built'. There are 34 possible endings for a verb in English, but verbs whose base ends in /d/ or /t/ make up between 35-42% of all irregular verbs. – Araucaria
There is one class of irregular verbs that have only one verb form in the present, past, and past participle: they are monosyllabic verbs ending in d or t, and they do stack the deck somewhat.
But only somewhat.
Here's a list of English irregular verbs. As you can see, they don't all end in d or t.
And here's a list of the monosyllabic t/d-final zero-inflected verbs on that list:
This is one class of irregular verb; there are many such, but this one is unique.
Each of these verbs
Note that there are other irregular verbs in the list that have the first two characteristics above, but not the third. Read, read, read, for instance, does not have identical forms in sound, only spelling, which doesn't count; and lead, led, led and breed, bred, bred work the same way, but with better spelling. And then there's eat, ate, eaten. But read, breed, lead, and eat aren't in this verb class.
(comment)
Maybe I should withdraw this, but I think my misconstruction of the question was not uncommon, so I will note that, after rereading, I recognize that the actual question concerns a bias towards irregularity in all verbs whose plain forms end in a 'd' sound. (And it appears that the OP even limits the question to the voiced d.)
In which case, he may be sensitive to the doubling of d sounds, as noted by others, but has a workaround rule in '-ed', also noted by others.
(Off the top of my head, just a few more of the short regular verbs ending in the d sound that take the workaround:
add, aid, bead, (bide goes both ways), brood, bud, (chide goes both ways), crowd, crud, confide, deed, (fud is a bit new in coinage), flood, gad, goad, hood, (i-d is a bit new in coinage as a verb), jade, kid, load, lead (as in applying the metal -- not the verb that conjugates to led), (mod is a bit too recent, maybe), (mead and mud might be too technical in context), need, nod, pad, (plead goes both ways), plod, pride, prod, raid, (reed might be too technical), (rid goes both ways), rod, seed, side, (sod goes both ways, I guess), stead, stud, tide, thread, void, wade, weed, wad, wood, ...
Why these are not irregular would be an interesting subject of study, and would help parameterize the suppression.
And I'm falling asleep. 8-)
Surveying all verbs to find all verbs ending in the d sound is going to be a large task unless one happens to have a dictionary of verbs in computer readable form handy.
The reverse task, to list all irregular verbs and examine the etymology of their morphologies for the application of a suppression mechanism might be quicker if such a dictionary is not handy.
(end comment)
It is an availability bias. You can find some lists of irregular verbs in the Oxford English Dictionary and on wikipedia. The verbs in those lists which end with a "d" are in the minority, actually.
(addendum: the list of irregular verbs, borrowed from wikipedia and wiktionary, non-basic forms removed, flagged for final d/t.)
Examples of irregular verbs not ending in "d" include fly, sew, run, begin, think, swim, lie, and so forth.
The conjugations do have patterns, which are discussed to some extent on the wikipedia page, see the discussion of strong vs. weak verbs.
And there seem to be patterns relative to the plain form ending in "d", but I'm not familiar enough with this information to describe them. Country of origin seems to play a large part, but that's not all.
So, is this an actual pattern, or am I just imagining it?
And if it is a real pattern, what's the explanation?
The answer seems simple. If verbs form a past tense according to a pattern, they could not be "irregular". They would form a class of verbs conforming to that pattern.
Perhaps some of these "irregular" verbs did, in the past, form the past tense conforming to a pattern . That would have been before any recording of English or its predecessors, and, the mechanism of that pattern would be unavailable to us now. One might guess as to undocumented mechanisms in English, but, guesses are not facts.
One will have to accept some verbs as "irregular", and so, not part of a pattern. If there were some known pattern, those verbs would not be "irregular".
Perhaps an unidentified mechanism caused "I go" and "I went" in current English to be unlike each other as "eo" (I go) and ivi" (I went) Wiktionary were in Classical Latin. I'd be interested in knowing, but I doubt any proof can be dug up to substantiate it.
