I have discussed the conditional nature of biblical (and modern) prophecy (see Resources on Joseph Smith's Prophecies for posts addressing this). This is not unique to biblical and modern revelation. One can find conditional prophecies in other literature from antiquity:
Conditional
Oracles.
One of the more common types of the
two-part response oracle is the conditional oracle. When the condition(s)
described in the protasis (introduced by such particles as “if” and “when”) was
fulfilled, then the prediction expressed in the apodosis was expected to take
place. This oracular form is of particular relevance for the study of early
Christian prophetic speech forms since it resembles the “pronouncement of
sacral law” . . . a typical example of a conditional oracle is the following
two-line oracle in hexameter preserved in an inscription from the sanctuary of
Grynaion Apollo in Aetolia:
When you honor Leto’s son Phoebus [Apollo]
and Zeus Patroios,
you will receive fame; then fasten your shackles here on the tree.
In this oracle the predictive
statement in line two is dependent on the fulfilment of the vaguely worded
ritual prescription in the first line. In another example a sick and dissolute
youth from Assyria reportedly received this incubation oracle in the temple of
Asklepios at Aegae:
If you would consult Apollonius you
would get better. (Philostratus, Vita Apoll. i.9)
This oracle is an uncommon example of
a conditional oracle containing both protasis and apodosis in a single prose
line.
Many conditional oracles were couched
in such ambiguous language that the “proper” interpretation of the oracle was
difficult if not impossible to determine. An example of a conditional homonymic
oracle, one whose obscurity was based on a double entendre, is the Delphic
oracle given to Aristomenes and Theoclus the mantic, who had come from Eira in
Messene to inquire about the safety of their homeland:
When a goat [tragos] drinks of
the winding stream of Neda,
no longer do I protect Messene, for destruction is at hand. (Pausanias iv.20.1)
Only Theoclus understood that the tragos
did not refer to a goat, but was a distinctive Messenian term for a wild fig
tree. Since such a tree was known to be bent over into the waters of the Neda
River, Theoclus and Aristomenes knew that the days of Messene were numbered.
A conditional oracle in a different form
is the oldest recorded oracle (third century B.C.) from the sanctuary of Apollo
at Claros. It related to the refounding of Smyrna, which had been destroyed
early in the third century by Lysimachus:
Thrice, yes, four times blest [makares]
will those men be
who shall dwell in Pagus beyond the Sacred Meles. (Pausanias vii.5.2)
In this oracle the apodosis is in the
first line and contains a promise, the enjoyment of which is conditional, based
on the future fulfilment of the protasis, which constitutes the second line.
Many of the conditional oracles which
we have discussed are conditional promises of fame, health, and general
well-being. A great many conditional oracles, however, are conditional threats
of disaster and destruction frequently propounded as riddles. In form such
oracles resemble the conditional formulas found in ancient epitaphs. (David E.
Aune, Prophecy in Early Christianity and the Ancient Mediterranean World [Grand
Rapids, Mich.: Eerdmans, 1983], 60-61)