Abduction - A form of nondeductive inference, also known as inference to the best explanation. The Surprise
Principle and the Only Game in Town Fallacy are relevant to deciding how strong an abductive inference is.
Analogy argument – a nondeductive inference in which one infers that a target object T has some characteristic
on the ground that T is similar to some other object A the analog), and A is known to possess that characteristic.
(e.g. Other galaxies probably contain life, since they are quite similar to our own galaxy and our own galaxy
contains life.) The strength of analogy arguments is an issue relevant to the Argument of Design and to the
problem of other minds.
Analytic – An analytic sentence is one whose truth or falsehood is deductively entailed by definitions. Many
philosophers have held that mathematical statements are analytic. If a sentence isn’t analytic it is synthetic.
A posteriori – a proposition that can be known or justified only be sense experience. An a posteriori argument is
an argument in which at least one premises is an a posteriori proposition.
A priori – a proposition that can be known or justified independent of sense experience. An a priori proposition
can be known or justified by reason alone (once you grasp the constituent concepts). Truths of mathematics and
definitions are often thought to be a priori. An a priori argument is an argument in which all the premises are a
priori propositions. The Ontological Argument for the existence of God was supposed to be an a priori argument.
Argument from Design – an a posteriori argument that God exists, advanced by Aquinas and Palely, criticized
by Hume. The argument claims that some feature of the world (like the simplicity of its laws or the fact that
organisms are intricate and well-adapted) should be explained by postulating the existence of an intelligent
designer, namely God.
Argument from Evil – an argument that claims that the existence of evil shows either that there is no God, or
that God can’t be all-powerful, all knowing, and all good.
Axiom – in mathematics, a starting assumption from which conclusions (theorems) are deduced.
Begging the question/Circularity – an argument begs the question when you wouldn’t accept the premises
unless you already believed the conclusion.
Birthday Fallacy – the error in reasoning that one would make in thinking that “everyone has a birthday”
deductively implies that “there is a single day on which everyone was born”.
Causal argument for the existence of God – an argument that Descartes gives in the Meditations for the claim
that God exists and s no deceiver: Since (1) I have an idea of a perfect being, and (2) there is at least as much
perfection in the cause as there is in the effect, it is said to follow that the cause of that idea must be a perfect
being, namely God.
Clarity/Distinctness Criterion – Descartes maintained that if a belief is clear and distinct, then it can’t fail to be
true. The reason clear and distinct ideas must be true is that God exists and is no deceiver.
Compatibilism – the thesis that free will and determinism are compatible. Soft determinism is a version of
compatibilism. Hard determinism and libertarianism are incompatibilist theories.
Compatibility – two propositions are compatible if the truth of one wouldn’t rule out the truth of the other. (e.g.
(1) this shirt is blue; (2) this shirt is torn. (1) and (2) are compatible. This doesn’t mean that either is true.
Conditional – an if/then statement. The if-clause is called the antecedent; the then clause us caked the
Conservation law – a law in physics that says that some quantity (like matter or mass/energy) can neither
increase or decrease in a closed system.
Contingent – a being is contingent if it exists in some but not all possible worlds; a proposition is contingent if it
is true in some but not all possible worlds. You are an example of a contingent thing; though you exist in the
actual world, you could have failed to exist.
Counterexample – a counterexample to a generalization is an object that refutes the generalization. A rotten
apple in the barrel is a counterexample to the claim “all apples in this barrel are unspoiled”.
Deductive validity – an argument is deductively valid because of the logical form it has. A deductively valid
argument is one in which the conclusion must be true if the premises are true.
Determinism – the thesis that a complete description of the causal facts at one time uniquely determines what
must happen next. There is only one possible future, given a complete description of the present. Newtonian
physics says that the behavior of physical objects is deterministic.