For more general information about English verb
inflection and auxiliary usage,
see English verbs and English clause syntax. For details of the uses of the
particular modals, see § Usage of specific verbs below.
The modals
can
and
could
are
from Old English
can(n)
and
cuþ
, which were
respectively present and preterite forms of the verb
cunnan
("to be able"). The
silent
l
in the spelling of
could
results from analogy with
would
and
should
.
Similarly,
may
and
might
are from Old English
mæg
and
meahte
, respectively
present
and preterite forms of
magan
("may, to be able");
shall
and
should
are
from
sceal
and
sceolde
, respectively present and preterite forms of
sculan
("to owe,
be obliged"); and
will
and
would
are from
wille
and
wolde
, respectively present and
preterite forms of
willan
("to wish, want").
The
aforementioned
Old
English
verbs
cunnan
,
magan
,
sculan
,
and
willan
followed the preterite-present paradigm (or, in the case of
willan
, a
similar but irregular paradigm), which explains the absence of the ending
-s
in the
third person on the present forms
can
,
may
,
shall
, and
will
. (The
original Old
English forms given above were first and third person singular forms; their
descendant forms became generalized to all persons and numbers.)
The verb
must
comes from Old English
moste
, part
of the verb
motan
("to be able
to, be obliged to"). This was another preterite-present verb, of which
moste
was in
fact the preterite (the present form
mot
gave rise to
mote
, which was used as a
modal
verb in Early Modern English; but
must
has now lost its past connotations
and has replaced
mote
). Similarly,
ought
was originally a past form—it derives
from
ahte
, preterite of
agan
("to own"), another Old English preterite-present verb,
whose
present
tense
form
ah
has also
given the
modern
(regular)
verb
owe
(and
ought
was formerly used as a past tense of
owe
).
The verb
dare
also originates from a preterite-present verb,
durran
("to dare"),
specifically
its present tense
dear(r)
, although in its non-modal uses in Modern
English it is conjugated regularly. However,
need
comes from the regular Old
English verb
neodian
(meaning "to be necessary")—the
alternative third person
form
need
(in place of
needs
), which has become the norm in modal uses, became
common in the 16th century.