Modalities are words which indicate the level of certainty
with which a claim can be made.
Every claim has some probability of being true. Some
claims are true beyond any reasonable doubt. For instance, we are
quite certain that the earth is roughly a sphere. Other claims
are not so certain. For instance, "There is life on other
might be, but no one really knows. If someone says, "There's
no doubt about it, there is life on other planets," they used
a modality which is too high. If someone says, "There's no
doubt about it, there is life on Earth," they've used an appropriate
modality. "There's no doubt about it" is the modality
in this case.
It is important to use the proper modality. You don't want to overstep
your evidentiary limits. In other words, don't say "certainly" if
you can't prove the claim with certainty.
When someone uses a high modality, they are saying that the truth
of the claim is certain.
- Certainly, definitely, there is no doubt about it, without question,
absolutely, for sure, beyond a doubt, positively, necessarily
- No question about it, the car needs a valve job.
- Absolutely, the defendant was not at the scene of the crime.
- All men are mortal (Note that the absence of any qualifying words
indicate a high modality.)
Claims with high modalities require deductive
arguments to prove them.
When someone uses a low modality, they are saying that the truth
of the claim is likely, but not certain.
- Probably, possibly, there's a good chance that, perhaps, maybe,
more than likely, might be
- I will probably go to Yale when I finish junior college.
- There might be life on other planets.
- There's a chance of rain by morning.
Claims with low
modalities require only inductive arguments to support them.
- High modalities are limited to certainty. But there is quite
a range for low modalities from almost certain to almost impossible.
Here's a guideline for the range of low modalities:
- 99% ± Virtually certain: overwhelming evidence in its
favor. Example: The law of gravity
- 90% ± Highly probable: very good evidence in its favor.
- 70% ± Probable: sufficient evidence in its favor. Example:
Most medicines have to pass this test to be approved.
- 50% ± Possible: either no evidence or equal evidence
for both sides. The Packers will kick off this Sunday. (A coin
toss determines which team kicks off just before the game.)
- 30% ± Improbable: insufficient evidence in its favor.
Example: That numerology helps people rise to fame and fortune.
- 10% ± Highly improbable: very little evidence in its
favor. Example: The theory that Jesus spent his early years studying
with a Hindu guru.
- 1% ± Virtually impossible: almost no evidence in its
favor. Example: The existence of unicorns.