Cosmological argument: AQA B grade notes

Aquinas’ Third Way aims to show a posteriori (from experience) that belief in God can be inductively supported (through evidence) by reason.
It is based on the difference between contingent and necessary beings.
P1. We observe that there are contingent beings (things that can possibly not exist).
P2. If it is possible for something to not exist, then there is some time in which it doesn’t exist.
C1. If everything were contingent, then at one time nothing existed.
P3. If nothing once existed, nothing could begin to exist, so nothing would exist now.
C2. So, there must be something that is not contingent, “having of itself its own necessity … That thing we call God.”
Aquinas argues that contingent things need an explanation for their existence.
Some things may be necessary because of something else, but this still does not fully explain existence.
So there must be a being that exists necessarily in itself.
This being explains why anything exists at all and is what we call God.

Cosmological arguments are a posteriori, meaning based on observation.
For example, Aquinas looks at motion, causation and contingency in the world.
They are inductive, so their premises support the conclusion but do not prove it.
This means they cannot give certainty, only show what is likely.
They are also defeasible, so new evidence could challenge them.
These arguments often use principles such as the Principle of Sufficient Reason, that everything has an explanation, and the causal principle, that everything caused has a cause.
These ideas come from experience, since we see things have causes.
But applying them to the whole universe is not straightforward.
The move from these principles to God involves extra assumptions.
So the argument does not prove God, but only makes God more likely.

The fallacy of composition
Weakness: The fallacy of composition attacks the assumption that the universe as a whole requires an explanation just because its parts do.
Strength: Cosmological arguments start with what we observe and don’t even mention the universe as a whole, which avoids fallacious part to whole reasoning.
The im/possibility of an infinite regress
Strength: An infinite regress may lead to paradoxes regarding infinite library examples and traversing an infinite to get to the current moment.
Weakness: Scientific models and the lack of empirical evidence undermine claims that an infinite regress is impossible, weakening philosophical arguments against it.
The brute fact
Weakness: The possibility of brute facts suggests that not everything requires an explanation, challenging the principle of sufficient reason.
Strength: The consistent practice of seeking explanations in science and philosophy supports the idea that reality is intelligible and may have an ultimate explanation.
The Im/possibility of a necessary being
Weakness: The concept of a necessary being is criticised as logically incoherent, since anything that can be conceived to exist can also be conceived not to exist.
Strength: Cosmological arguments reference God’s necessity as metaphysical rather than logical, avoiding the ontological argument’s issue of thinking existence is a predicate.

Cosmological arguments assume the causal principle, that every event has a cause.
But Hume argues this is not certain.
We can imagine an event happening without a cause, so it is not logically necessary.
Also, observing causes in the world does not prove the universe itself has a cause.
So there is no strong basis for the causal principle.

Counter

Aquinas uses sustaining causation.
Observed things are “secondary causes” that depend on something else for their causal power.
This chain must end in a first cause with its own power.
A cause with no cause would be contradictory on this view.

Evaluation

This is unconvincing because sustaining causation is not supported by science.
Physics explains events through prior states and laws without needing a continuing first cause.
Theories like inflation suggest the universe could arise without added cause or energy.
So there is no clear need for Aquinas’ idea.
Hume is right that the causal principle may not apply to everything, so God is not required as an explanation.

Russell argues that what is true of parts is not always true of the whole.
Even if everything in the universe has a cause, it does not follow that the universe itself has a cause.
So the argument may commit the fallacy of composition, assuming the whole must be explained in the same way as its parts.

Counter

Copleston argues the argument does not depend on this mistake.
It focuses on a series of contingent things and claims the whole series still needs an explanation.
Even if each part is explained and the series is infinite, it cannot explain why the series exists at all.

Evaluation

This response is not convincing because it treats a series as if it were a separate thing.
Hume argues that explaining each part explains the whole collection.
A series is just a way of grouping parts in our thinking, not a real thing needing its own cause.
So it does not need a further explanation beyond its parts.
If each part is explained, the series is fully explained.
This weakens the cosmological argument, because it shows no extra explanation is needed.

Hume argues that necessity only applies to logical truths, like “1+1=2”.
We can imagine anything not existing, so there is no contradiction in denying God’s existence.
This means the idea of a necessary being does not make sense.
Russell agrees, saying necessity applies to statements, not real things.

Counter

Copleston argues this misunderstands cosmological arguments.
They do not claim God is logically necessary, but that God is needed to explain the world.
If the universe is contingent, it must have an explanation.
So necessity here means being required as an explanation, not logically unavoidable.

Evaluation

Hume’s argument is still more convincing.
Even if we accept that a necessary being could exist, there is no clear reason to think this must be God.
The necessary being could instead be the universe itself or some basic physical reality.
Modern science supports this possibility, with some theories suggesting underlying structures like quantum fields which could be necessary.
These could explain why anything exists without appealing to God.
So the argument fails to justify belief in a divine necessary being.