DebateLabKIT/deepa2-corpus · Datasets at Hugging Face

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the last effect.
P5. If a cause is removed from an ordered series of effi cient causes, then
the effects after that cause are removed as well.
C3. If there were no fi rst cause, then there would be no subsequent effects
(instantiation, P4, P5).
P6. If an ordered series of effi cient causes could precede infi nitely, then there
would be no fi rst cause.
C4. If an ordered series of effi cient causes could precede infi nitely, then
there would be no subsequent effects (hypothetical syllogism, C3, P6).
P7. But there are subsequent effects.
C5. An ordered series of effi cient causes cannot precede infi nitely ( modus
tollens , C4, P7).
P8. An ordered series of effi cient causes either precedes infi nitely, terminates
in a cause that causes itself, or terminates in an uncaused cause.
C6. An ordered series of effi cient causation terminates in an uncaused
cause (disjunctive syllogism, C2, C5, P8).
C7. We call that uncaused cause “ God ” (defi nition).
14 Timothy J. Pawl
The Third Way – The Argument from Possibility
and Necessity
Aquinas has a specifi c understanding of possibility and necessity in mind
in the Third Way, and it is not the common understanding in today ’ s philosophical
discussions. When Aquinas calls something “ necessary, ” in this
argument, he means that it is not subject to generation or corruption. A
necessary being exists, but it does not come into existence by composition,
and it cannot cease existing by way of decomposition. Similarly, a possible
being, in this context, exists, but it does or could have come into existence
by way of composition, and it can cease to exist by way of decomposition.
The most debated inference in this argument is the inference from P3 to
C2. Most commentators who attempt to justify it do so by arguing that
Aquinas had in mind an implicit premise which, together with P3, entails
C2. As it stands, without the help of an implicit premise, the inference is
invalid and commits the fallacy of composition.
Certain of the things we fi nd in the world are able to exist and able not
to exist; for some things are found to be generated and corrupted and, as a
result, they are able to exist and able not to exist.
But it is impossible that everything should be like this; for that which is
able not to exist is such that at some time it does not exist. Therefore, if
everything is such that it is able not to exist, then at some time nothing existed
in the world. But if this were true, then nothing would exist even now. For
what does not exist begins to exist only through something that does exist;
therefore, if there were no beings, then it was impossible that anything should
have begun to exist, and so nothing would exist now – which is obviously
false. Therefore, not all beings are able to exist [and able not to exist]; rather,
it must be that there is something necessary in the world.
Now every necessary being either has a cause of its necessity from outside
itself or it does not. But it is impossible to go on to infi nity among necessary
beings that have a cause of their necessity – in the same way, as was proved
above, that it is impossible to go on to infi nity among effi cient causes.
Therefore, one must posit something that is necessary per se , which does not
have a cause of its necessity from outside itself but is instead a cause of necessity
for the other [necessary] things. But this everyone calls God. (ST I, q2,
a3, response)
P1. Some things are able to be generated or corrupted.
P2. If some things are able to be generated or corrupted, then it is possible
for those things either to exist or not to exist.
C1. It is possible for some things to exist or not to exist ( modus ponens ,
P1, P2).
Aquinas’ Five Ways 15
P3. If, for each thing, it is possible that it not exist, then at some time it
does not exist.
C2. If, for each thing, at some time it does not exist, then at some time
nothing exists (universal generalization, P3).
P4. If at some time nothing exists, then there would have been nothing to
cause another thing to exist.
P5. If there had been nothing to cause another being to exist, then nothing
could have come into existence.
P6. If nothing could have come into existence, then nothing would exist
even now.
P7. But something does exist now.
C3. Something could have come into existence ( modus tollens , P6, P7).
C4. There had to have been something to cause another thing to exist
( modus tollens, P5, C3).
C5. At no time did nothing exist ( modus tollens , P4, C4).
C6. It is not true that, for each thing, at some time it does not exist
( modus tollens , C2, C5).
C7. There must be something that is not possible not to exist – that is,
there must be a necessary being ( modus tollens , P3, C6).
P8. A necessary being has a cause for its necessity from something else or
it does not.
P9. It is not possible for there to be an infi nite series of beings with their
necessity from something else.
C8. There must be some necessary being with its necessity not from
something else (disjunctive syllogism, P8, P9).
C9. We call that necessary being whose necessity comes from nothing
else “ God ” (defi nition).
The Fourth Way – The Argument from Gradation
In the Fourth Way, Aquinas relies on two arguments from Aristotle, which
he does not provide in the text, to justify two of his premises (P3 and P4).
P1 is observably true. P2 requires a scope restriction. Aquinas seems to be
saying that any comparative predications of a property entail that there
exists something that is maximally that property. If this were true, then if
Bob is fatter than Tom, then there must be something that is maximally fat.
Worse still, from P4, it would follow that this fattest thing would be the
cause of all other fat things. It seems better to restrict P2 to perfections and
then take heat (his example) to be a form of perfection (note that this is
just an example; one can grant his point while denying that heat is a perfection).
C4 seems to commit the fallacy of composition. Even if it were proven
16 Timothy J. Pawl
that there is a thing that is most good, and a thing that is most noble, and

the last effect.

P5. If a cause is removed from an ordered series of effi cient causes, then

the effects after that cause are removed as well.

C3. If there were no fi rst cause, then there would be no subsequent effects

(instantiation, P4, P5).

P6. If an ordered series of effi cient causes could precede infi nitely, then there

would be no fi rst cause.

C4. If an ordered series of effi cient causes could precede infi nitely, then

there would be no subsequent effects (hypothetical syllogism, C3, P6).

P7. But there are subsequent effects.

C5. An ordered series of effi cient causes cannot precede infi nitely ( modus

tollens , C4, P7).

P8. An ordered series of effi cient causes either precedes infi nitely, terminates

in a cause that causes itself, or terminates in an uncaused cause.

C6. An ordered series of effi cient causation terminates in an uncaused

cause (disjunctive syllogism, C2, C5, P8).

C7. We call that uncaused cause “ God ” (defi nition).

14 Timothy J. Pawl

The Third Way – The Argument from Possibility

and Necessity

Aquinas has a specifi c understanding of possibility and necessity in mind

in the Third Way, and it is not the common understanding in today ’ s philosophical

discussions. When Aquinas calls something “ necessary, ” in this

argument, he means that it is not subject to generation or corruption. A

necessary being exists, but it does not come into existence by composition,

and it cannot cease existing by way of decomposition. Similarly, a possible

being, in this context, exists, but it does or could have come into existence

by way of composition, and it can cease to exist by way of decomposition.

The most debated inference in this argument is the inference from P3 to

C2. Most commentators who attempt to justify it do so by arguing that

Aquinas had in mind an implicit premise which, together with P3, entails

C2. As it stands, without the help of an implicit premise, the inference is

invalid and commits the fallacy of composition.

Certain of the things we fi nd in the world are able to exist and able not

to exist; for some things are found to be generated and corrupted and, as a

result, they are able to exist and able not to exist.

But it is impossible that everything should be like this; for that which is

able not to exist is such that at some time it does not exist. Therefore, if

everything is such that it is able not to exist, then at some time nothing existed

in the world. But if this were true, then nothing would exist even now. For

what does not exist begins to exist only through something that does exist;

therefore, if there were no beings, then it was impossible that anything should

have begun to exist, and so nothing would exist now – which is obviously

false. Therefore, not all beings are able to exist [and able not to exist]; rather,

it must be that there is something necessary in the world.

Now every necessary being either has a cause of its necessity from outside

itself or it does not. But it is impossible to go on to infi nity among necessary

beings that have a cause of their necessity – in the same way, as was proved

above, that it is impossible to go on to infi nity among effi cient causes.

Therefore, one must posit something that is necessary per se , which does not

have a cause of its necessity from outside itself but is instead a cause of necessity

for the other [necessary] things. But this everyone calls God. (ST I, q2,

a3, response)

P1. Some things are able to be generated or corrupted.

P2. If some things are able to be generated or corrupted, then it is possible

for those things either to exist or not to exist.

C1. It is possible for some things to exist or not to exist ( modus ponens ,

P1, P2).

Aquinas’ Five Ways 15

P3. If, for each thing, it is possible that it not exist, then at some time it

does not exist.

C2. If, for each thing, at some time it does not exist, then at some time

nothing exists (universal generalization, P3).

P4. If at some time nothing exists, then there would have been nothing to

cause another thing to exist.

P5. If there had been nothing to cause another being to exist, then nothing

could have come into existence.

P6. If nothing could have come into existence, then nothing would exist

even now.

P7. But something does exist now.

C3. Something could have come into existence ( modus tollens , P6, P7).

C4. There had to have been something to cause another thing to exist

( modus tollens, P5, C3).

C5. At no time did nothing exist ( modus tollens , P4, C4).

C6. It is not true that, for each thing, at some time it does not exist

( modus tollens , C2, C5).

C7. There must be something that is not possible not to exist – that is,

there must be a necessary being ( modus tollens , P3, C6).

P8. A necessary being has a cause for its necessity from something else or

it does not.

P9. It is not possible for there to be an infi nite series of beings with their

necessity from something else.

C8. There must be some necessary being with its necessity not from

something else (disjunctive syllogism, P8, P9).

C9. We call that necessary being whose necessity comes from nothing

else “ God ” (defi nition).

The Fourth Way – The Argument from Gradation

In the Fourth Way, Aquinas relies on two arguments from Aristotle, which

he does not provide in the text, to justify two of his premises (P3 and P4).

P1 is observably true. P2 requires a scope restriction. Aquinas seems to be

saying that any comparative predications of a property entail that there

exists something that is maximally that property. If this were true, then if

Bob is fatter than Tom, then there must be something that is maximally fat.

Worse still, from P4, it would follow that this fattest thing would be the

cause of all other fat things. It seems better to restrict P2 to perfections and

then take heat (his example) to be a form of perfection (note that this is

just an example; one can grant his point while denying that heat is a perfection).

C4 seems to commit the fallacy of composition. Even if it were proven

16 Timothy J. Pawl

that there is a thing that is most good, and a thing that is most noble, and