The Four Pathways to Counterfactuality

In certain situations a past tense marker in conjunction with another word, gives a sentence a counterfactual meaning. For example “In present day English “if you competed tomorrow, you would win” implies that the competing (and the winning) will probably not take place. That is the past tense marker in conjunction with "if" gives an irrealis vibe to the sentence. Also the past tense meaning has been lost. There is a grammatical process behind this shift of meaning. I describe four "pathways" that have produced counterfactuality within the historical English period. I contend that this process split "ought" from "owe" and "might" from "may" well over a thousand years ago. And more recently split "should" from "shall", "would" from "will" and "could" from "can". In present day English, in certain situations the first element is simply the past of the second element. But this is just a holdover from ancient times. All ten words listed here are definitely separate words. You might has noticed that I mentioned "irrealis vibe" in the first paragraph. This is because the counterfactual (or irrealis, same thing) markers are never absolute, they are never 100% counterfactual. Indeed we have negation markers for that job (like "not" (usually along with "do") in English). I believe that all counterfactual markers have a valve of about "90% not going to happen" (AKA 90% counterfactual or 90% irrealis) when they first split off from the mother word. However over time, this percentage can vary, as indeed any part of the meaning can vary. One could say that counterfactual markers are the unintended detritus of an unplanned grammaticalization process. OK, but are they useful ? Mmmh, well they are used. So I guess you could say that they are useful. But we mustn't be so self-centred to think that all that exists in nature is put there to serve us.