Editing Shall and will (section)

==''Should'' and ''would''==

As noted above, ''should'' and ''would'' originated as the [[preterite]] (past tense) forms of ''shall'' and ''will''. In some of their uses they can still be identified as past (or conditional) forms of those verbs, but they have also developed some specific meanings of their own.

===Independent uses===
The main use of ''should'' in modern English is as a synonym of ''[[ought to]]'', expressing quasi-obligation, appropriateness, or expectation (it cannot be replaced by ''would'' in these meanings). Examples:
* You should not say such things. (it is wrong to do so)
* He should move his pawn. (it is optimal to do so) 
* Why should you suspect me? (for what reason is it proper to suspect me?)
* You should have enough time to finish the work. (a prediction)
* I should be able to come. (a prediction, implies some uncertainty)
* There should be some cheese in the kitchen. (expectation)

Other specific uses of ''should'' involve the expression of [[irrealis mood]]:
* in condition clauses ([[protasis]]), e.g., "If it should rain" or "Should it rain"; see [[English conditional sentences]]
* as an alternative to the subjunctive, e.g., "It is important that he (should) leave"; see [[English subjunctive]]

The main use of ''would'' is in conditional clauses (described in detail in the article on [[English conditional sentences]]):
*I would not be here if you hadn't summoned me.
In this use, ''would'' is sometimes (though rarely) replaced by ''should'' when the subject is in the first person (by virtue of the same prescriptive rule that demands ''shall'' rather than ''will'' as the normal future marker for that person). This ''should'' is found in stock phrases such as "I should think" and "I should expect". However its use in more general cases is old-fashioned or highly formal, and can give rise to ambiguity with the more common use of ''should'' to mean ''ought to''. This is illustrated by the following sentences:  
* You would apologize if you saw him. (pure conditional, stating what would happen)
* You should apologize if you see him. (states what would be proper)
* I would apologize if I saw him. (pure conditional)
* I should apologize if I saw him. (possibly a formal variant of the above, but may be understood to be stating what is proper)

In archaic usage ''would'' has been used to indicate present time desire. "Would that I were dead" means "I wish I were dead". "I would fain" means "I would gladly".

More details of the usage of ''should'', ''would'' and other related auxiliaries can be found in the article on [[English modal verbs]].

===As past of ''shall'' and ''will''===
When ''would'' and ''should'' function as past tenses of ''will'' and ''shall'', their usage tends to correspond to that of the latter verbs (''would'' is used analogously to ''will'', and ''should'' to ''shall'').

Thus ''would'' and ''should'' can be used with "[[future-in-the-past]]" meaning, to express what was expected to happen, or what in fact did happen, after some past time of reference. The use of ''should'' here (like that of ''shall'' as a plain future marker) is much less common and is generally confined to the first person. Examples:
*He left Bath in 1890, and would never return. (in fact he never returned after that)
*It seemed that it would rain. (rain was expected)
*Little did I know that I would (''rarer:'' should) see her again the very next day.

''Would'' can also be used as the past equivalent of ''will'' in its other specific uses, such as in expressing habitual actions (see [[English markers of habitual aspect#Would]]):
* Last summer we would go fishing a lot. (i.e., we [[used to]] go fishing a lot)

In particular, ''would'' and ''should'' are used as the past equivalents of ''will'' and ''shall'' in [[indirect speech]] reported in the past tense:
*The ladder will fall. → He said that the ladder would fall.
*You shall obey me! → He said that I should obey him.
*I shall go swimming this afternoon. → I said that I should go swimming in the afternoon.
As with the conditional use referred to above, the use of ''should'' in such instances can lead to ambiguity; in the last example it is not clear whether the original statement was ''shall'' (expressing plain future) or ''should'' (meaning "ought to"). Similarly "The archbishop said that we ''should'' all sin from time to time" is intended to report the pronouncement that "We ''shall'' all sin from time to time" (where ''shall'' denotes simple futurity), but instead gives the highly misleading impression that the original word was ''should'' (meaning "ought to").