The Ultimate List of Apologetics Terms for Beginners (with Explanations)

Have you ever listened to a William Lane Craig debate and had to pause the video every 10 seconds to look up a term? If you are just getting into apologetics, debates and lectures can sound like they are speaking a different language. As with any specialized field, apologetics is laden with technical terminology. (That’s not a bad thing in an of itself; formal terminology is really useful past a certain point.) If you’re a beginner, as we all were at some point, this post is for you. Here is the ultimate list of apologetics terms for beginners.

Let me make a few notes. First, the terms are accompanied by common usages. Don’t make the mistake of thinking that dictionaries literally determine the meaning of words. Dictionaries are merely historical accounts of how terms are commonly used. Second, you may have seen some of these terms used in other contexts. Forget all that. We are discussing how these terms are used in the context of philosophy and apologetics. For example, outside of philosophy, the term ‘realist’ can refer to someone that relies on facts and past experience instead of hopes and dreams. In the world of philosophy, however, ‘realist’ means something completely different.

Third, the terms are organized alphabetically. If you’re having trouble finding a word–or just want to go faster–use the search function in your browser (usually just command+F). Fourth, consider bookmarking this page to make recalling it easier–some have even told me they plan to print it out. I suggest keeping this page open while listening to your favorite debates, podcasts, or lectures–searching this page will actually be a lot faster than Google. (If you’re a philosophy nerd, check this post out.)

Lastly, and this is really important, each term is hyperlinked to a more in-depth explanation. Some are videos but most are articles. You’ve been provided everything you need to start wrapping your mind around each term!

If you’d like a printable PDF of this post, it’s available to Patrons of $5 or more. You may also download it here for $1.99.

General Terms

a priori – knowledge independent of experience, like 2 + 4 = 6, all bachelors are unmarried, and the laws of logic.

a posteriori – knowledge dependent on experience, like science (atomic theory, the Big Bang, and so on).

Ad Hoc – The addition of an extraneous hypothesis to save a theory. Here’s an example of an ad hoc hypothesis: Jesus secretly had an identical twin brother that appeared to the disciples after Jesus’ death. To be fair, all hypotheses are ad hoc to some degree–that’s why philosophers usually talk about degree of ad hocness.

Antecedent (Logic) – The first half of a conditional “if, then” statement. Take the conditional statement: “If my name is William Lane Craig, I should have a beard.” The first half, “If my name is William Lane Craig” is called the antecedent.

Apologetics – A rational defense of religious truth claims–Christian apologists give a rational defense of Christianity. It comes from the Ancient Greek word apologia which means to give a defense (like in a court case).

Agnostic – A person that neither believes nor disbelieves that some claim is true. In the context of theism, an agnostic is someone that withholds judgement about God’s existence. There is debate over whether true agnosticism is even possible.

Atheism – Traditionally, atheism is the view that no deities exist. See also: Lack-theism.

Basic Belief – A basic belief is a belief that is not held on the basis of any argument. My belief about what I had for breakfast this morning, for example, is basic. I simply think about it, remember that I had Starbucks, and then form the belief “I drank an overpriced latte for breakfast.” In fact, most, if not all, of our memory beliefs are basic; they aren’t held on the basis of any argument. (See this post for more examples of basic beliefs.)

Bayesian Probability – An interpretation of probability that involves evaluating the prior probability of a hypothesis before looking at the evidence, which is then updated to a posterior probability after taking the evidence into account. This is complicated stuff, don’t expect to learn or grasp it very quickly. Watch this video for a more lengthy explanation.

Boltzmann Brain – A single brain that fluctuates into existence out of the quantum vacuum. On many multiverse theories, it is more likely that you are an unembodied brain with illusory memories and experiences–a Boltzmann Brain–than that you are an embodied person in a complex universe. This is another one of those concepts that takes a little to wrap your mind around. When you have time, watch this video for a fairly decent explanation.

Brute Fact – A fact that has no explanation. Some atheists say that the existence of the universe is a brute fact. By that they mean that the universe just happens to exist; there’s no reason for its existence.

Burden of Proof – Anyone that makes a claim is burdened to justify it, especially when challenged. For example, if I claim that all atheists are overweight, I am uniquely burdened to substantiate that claim–no one is burdened to refute it. Debates about who has the burden of proof about a particular claim can turn into “burden tennis” where neither party wants to defend their position. See also: Shifting of the Burden of Proof.

Causation – The kind of thing that happens when a cue ball knocks the nine ball into the corner pocket. The standard view is that causation involves at least two events: cause and effect. It’s important to note that the standard view has been objected to on all accounts. Also important to note (in the context of apologetics) is Aristotle’s “Four Causes.” See also: Efficient Cause, Material Cause.

Classical Theism – The view that God exists and is all-powerful, all-knowing, all-good, immanent, transcendent, simple, immutable, impassible, and timeless. See also: Theistic Personalism.

Cognitive Dissonance – Mental discomfort from having two or more inconsistent values, ideas, or beliefs. The discomfort is usually triggered by being presented new evidence or evidence they hadn’t considered in the past.

Cognitive Faculties – The mind is comprised of a set of faculties that perform various functions–sense, imagination, introspection, memory, thinking, and understanding. Reformed Epistemologists contend that if God exists, we probably have a sensus divinitatis, a kind of cognitive faculty that, when functioning properly, accurately produces beliefs about God. See also: Andrew Moon’s paper, “How to Use Cognitive Faculties You Never Knew You Had” Pacific Philosophical Quarterly (2018).

Confirmation Bias – The process of ignoring evidence and data that might disconfirm one’s existing beliefs or hypotheses. A type of selection bias, it can be displayed as one collects, interprets, or remembers data. Confirmation bias is sometimes caused by the desire to avoid cognitive dissonance (see above).

Consequent (Logic) – The second half of a conditional “if, then” statement. Take the conditional statement: “If I want to be taken seriously, then I shouldn’t be a presuppositionalist.” The second half, “then I shouldn’t be a presuppositionalist,” is called the consequent.

Contingent – As it relates to objects, contingent objects can fail to exist–they do not exist in all possible worlds. As it relates to propositions, contingent propositions are neither necessarily true nor necessarily false.

Contingent Property – Sometimes called “accidental property,” a contingent property of an object is an attribute that it happens to have but that it could lack. For example, I am a photographer. That is a contingent property of Cameron Bertuzzi. I didn’t have to be a photographer–I could have been a mechanic, dentist, barista, or any number of things. There is a possible world where I lack the property “being a photographer.” See also: Essential Property.

Contradiction – The incompatibility of two or more propositions. This is not always easy to see. Sometimes two propositions look contradictory but are not actually incompatible (e.g., the existence of God and Evil, check out Alvin Plantinga’s “God, Freedom, and Evil“). See also: Implicit vs Explicit Contradiction.

Cosmology – The study of the origin, evolution, and fate of the universe. Cosmology is the study of the universe at large and throughout its existence. Modern cosmology is dominated by the Big Bang theory.

Cosmogony – Any physical model concerning the origin of the universe. The scientific arguments in support of the Kalam Cosmological Argument are technically an appeal to cosmogonic data.

Defeater – A defeater is a proposition that prevents one from having knowledge and/or justification about a belief. For example, the Problem of Evil is a potential defeater of Christian belief. If the Problem of Evil is successful, then Christians either don’t know that Christianity is true, or they aren’t justified in believing that Christianity is true. See also: Rebutting vs Undercutting Defeaters.

Determinism – The view that all events, including our choices and actions, were causally determined to happen from the beginning of time.

Dualism – In the philosophy of mind, dualism is the idea that humans are composed of two radically different kinds of substances: mental and physical. In addition to having a physical body, we humans also possess immaterial minds.

Efficient Cause – That which brings a thing into being. The efficient cause of a rubber ball would be the actions of the factory and/or workers in which it was made. Importantly, efficient causes can be either personal or natural. The efficient cause of the heart, for example, “would be the biological processes that determined that certain embryonic cells would form into a heart rather than, say, a kidney or brain (Feser, Edward. The Last Superstition: A Refutation of the New Atheism (Kindle Locations 1300-1301)).”

Empirical Evidence – Information received from the five traditional senses (sight, taste, hearing, smell, and touch). Also referred to as “sensory experience.”

Epistemology – The study of knowledge and justified belief. Listen to our fourth podcast episode for an overview.

Eschatology – The study of “last things.” Christian eschatology looks to study and discuss matters such as death and the afterlife, Heaven and Hell, the Second Coming of Jesus, the resurrection of the dead, the Rapture, the Tribulation, Millennialism, the end of the world, the Last Judgment, and the New Heaven and New Earth in the world to come.

Essential Property – An essential property of an object is an attribute that it has of necessity. For example, many would say that I have the essential property “being a human.” There is no possible world where I do not have that attribute (worries about whether that property is actually essential are irrelevant for the illustration). See also: Contingent Property.

Evidentialism (Epistemology) – The view that a subject is justified in her belief only if the evidence adequately supports her belief. In the context of belief in God, evidentialism says that one is justified in believing in God only if her evidence supports her belief. In short, evidentialism is the view that justified belief requires evidence. See also: Hyperevidentialism; Reformed Epistemology.

Evidentialism (Apologetic Methodology) – The process of giving arguments and evidence to show that Christianity is true. See also: Presuppositionalism.

Evolution – The scientific theory that explains biological complexity through some specified mechanism (like natural selection) over long periods of time. Make sure to check out our series exploring the relation between Genesis and Evolution.

Eisegesis – The process of interpreting a text or portion of text in such a way that the process introduces one’s own presuppositions, agendas, or biases into and onto the text. This is commonly referred to as reading into the text. See also: Exegesis.

Euthyphro Dilemma – The Euthyphro Dilemma says that either God has reasons for his commands or He doesn’t. Take the second option. God has no reasons for His commands. Well then God’s commands are arbitrary–however, morality can’t be arbitrary. Now take the first option. God has reasons for His commands. Well then these reasons themselves are sufficient to give us moral obligations. No need for God. The Euthyphro Dilemma is meant to show that grounding morality in God is misguided. See this blog post for a response.

Exegesis – The process of drawing the meaning out of a text. It’s a way of letting the text speak for itself. See also: Eisegesis.

Explanatory Power – The ability of a hypothesis to effectively explain the data.

Explanatory Scope – A hypothesis has good explanatory scope if it explains all or most of the data. Hypotheses can have poor explanatory scope by explaining only some or none of the data.

Faith – People use faith in all sorts of ways, but the usage that concerns us is the biblical one, which is simply trust. For an explanation, check out this article.

Fallacy – An argument is fallacious when it makes “wrong moves” either in logic or reasoning. Fallacies can be formal or informal. A formal fallacy is a flaw in logical structure, such as when a conclusion doesn’t logically follow from the previous steps or premises. An informal fallacy is a flaw in reasoning, such as when one generalizes from too small a sample size. For a list of common fallacies, see the last section of this post.

Free Will – Roughly the idea that we are in control of our choices and actions. I was free to create this glossary of apologetics terms if my choice to do so was up to me.

Generic Theism – A kind of bare-bones monotheism, this is the view that there exists a being with the following properties: omnipotence, omniscience, omnibenevolence, and necessary existence. Generic Theism is compatible with the three Great Monotheistic Faiths: Islam, Judaism, and Christianity. See also: Perfect Being Theism.

God – God is a being that has at least the following properties: omnipotence, omniscience, omnibenevolence, and necessary existence. In the context of Christianity, God is a being that is all-powerful, all-knowing, perfectly good, all-loving, eternal, omnipresent, incorporeal (having no physical body), trinitarian, and metaphysically necessary. See also: Generic Theism.

Hiddenness – The idea that God is not as apparent as one would expect Him to be. He either ought to give us more evidence of His existence or be there to comfort us.

Hermeneutics – Principles of interpretation. Biblical hermeneutics is the study of the principles (or tools) of interpretation of the Bible.

Hyperevidentialism – Hyperevidentialism is an extreme form of evidentialism. It says that justified beliefs (about God) require a particular kind of evidence, namley, evidence that is publicly available. More technically, this view has three components. First, epistemic justification requires evidence. Second, evidence consists entirely of a certain kind of foundational propositions. Third, theistic beliefs (e.g. that God exists) are not among those foundations. See also: Evidentialism; Reformed Epistemology.

Interlocutor – A person involved in a conversation, dialogue, or debate. Two or more people interacting with each other in dialogue are interlocutors. The term is synonymous with “conversation partner.”

Intuition – Mental states or events in which a proposition seems true. Most of us share the intuition that the past is real–the world wasn’t created five minutes ago with the appearance of age.

Is/Ought Gap – David Hume famously argued that you can’t derive an ought, facts about what you ought to do, from an is, facts about the world. In his view, we can’t move from ‘observations about the world’ to ‘judgements about values’–otherwise there’s a gap in our reasoning. Watch this short clip.

Lack-theism – The view that one lacks belief in any gods. Note that anything can be a lack-theist, including babies, refrigerators, and rocks.

Logic – From the Greek word “logos,” logic is the study of reasoning. More narrowly, logic is the study of the principles and criteria of valid inferences or demonstration. A logical person reasons well; an illogical person reasons poorly. See also: Rules of Inference.

Material Cause – The underlying “stuff” that a thing is made out of. The material cause of a rubber ball is rubber. The material cause of your heart is muscle tissue.

Materialism – In church, this term can mean “an unhealthy love of material things.” However, in philosophy and apologetics, materialism is the view that only material things exist. Humans have no soul, they are physical objects. Immaterial gods don’t exist, etc.

Meta-ethics – The branch of ethics concerned with the nature of moral statements. Meta-ethical theories do not seek to establish which moral statements are correct, rather they are concerned with the nature of ethical statements–they seek to answer questions like: Is morality more a matter of taste than truth? Are moral standards culturally relative? Are there moral facts? If there are moral facts, what is their origin? See also: Moral Realism and Moral Anti-realism.

Metaphysics – Notoriously hard to define (within the philosophical tradition), it roughly means the study of existence, being, and the world. Artistotle called metaphysics the subject that deals with “first causes and the principles of things.” The following are metaphysical questions: Do we have free will? Does God exist? What is the nature of causation? What is consciousness? Do abstract objects (like numbers and mathematical objects) exist? See also: Ontology.

Modal Collapse – The claim that there is only one possible world. Modal collapse is, for most, an unwelcome conclusion. For example, some philosophers (like Peter van Inwagen) argue against the Principle of Sufficient Reason (see below) by claiming that some versions of it lead to modal collapse. See also: Possible World.

Modal Logic – The study of modal reasoning. A “modal” is an expression like “possibly” or “necessarily” that is used to qualify the truth of a statement. For example, I might qualify the statement “William Lane Craig is the GOAT” by saying that “William Lane Craig is possibly the GOAT.” Modal logic is therefore the study of reasoning about modal claims. Modal logic is also featured in Ontological Arguments.

Moral Anti-realism – The denial of the thesis that moral properties–or facts, objects, relations, events, etc.–exist mind-independently. Another way of saying it is that it’s a denial of Moral Realism (see below).

Moral Realism – The view that (i) moral claims do purport to report facts, and (ii) some moral facts exist. A moral claim is something like, “It is always wrong to torture infants for fun.” Moral realism says that these kinds of claims are truth-apt (they can be true or false), and that some of these claims are actually true.

Naturalism – The view that God does not exist and nothing like God exists. Naturalists themselves disagree over what “nothing like” includes, but here’s a start: the supernatural, ghosts, demons, fairies, abstract entities like numbers mathematical objects, lesser deities (like Thor), and so on. This is another one of those terms that is difficult to define. Pro tip: if you see someone use it, ask how they define it.

Objective Morality – The view that some moral claims are objectively true in the same sense that it is objectively true that Dallas is North of Houston. Here’s a moral claim: Shoplifting is wrong. On moral objectivism, the claim that shoplifting is wrong is a fact about reality.

Ontology – The study of what there is and what features those things have. Some examples of ontological questions: Does God exist? Do abstract objects, like numbers, exist? What properties does God have? Can abstract objects stand in causal relations? Ontology is a subdiscipline of Metaphysics.

Original Sin – The Christian doctrine that says our sinful nature is related in some significant way to Adam’s sin in the Garden. There are wide range of views on Original Sin–dedicate some time to listen to this important podcast episode from Dr. Glenn Peoples on the subject.

Perfect Being Theism – The view that we should understand God as the greatest conceivable being–a Maximally Great Being. And there can be no greater being than one that is perfect. A question one might ask is, what kinds of properties would a perfect being have? What are the great-making properties? Traditionally, perfect being theologians have said that God is at least maximally powerful, maximally knowledgeable, maximally good, and metaphysically necessary.

Possible World – A possible world is a complete description of how the world might or could have been. There is a possible world, for example, where Hillary Clinton beat Donald Trump in the 2016 election. Importantly, possible worlds aren’t possible planets or galaxies or universes, possible worlds are descriptions of a complete reality. The actual world, the world we live in, is a way the world could have been, and so even the actual world is a possible world.

Premise – A statement in an argument that is meant to justify or lead to a conclusion. Premises are not conclusions. See this brief video for an explanation.

Presuppositionalism (Apologetic Methodology) – The process of assuming (or presupposing) that Biblical Christianity is true in order to show that Christianity is true. See also: Evidentialism.

Principle of Sufficient Reason (PSR) – This principle says that contingent facts and/or objects have or can have explanations. Anything that is contingent can fail to exist. There are many different versions of the PSR (it’s always best to ask which version is under discussion if it hasn’t already been made clear). The PSR is featured primarily in Cosmological Arguments.

Proper Function – The idea that something is meant to function a certain way. For example, the heart is functioning properly when it is pumping blood throughout the body. A schizophrenic is experiencing cognitive malfunction–his brain is failing to function properly. This concept is featured heavily in Plantinga’s work.

Properly Basic Belief – A properly basic belief is a basic belief that is held rationally. Not all basic beliefs, beliefs that are held not on the basis of argument, are rational. I might go to a casino and find myself believing without argument that my next roll will make me a billionaire. But that belief is hardly rational. Alternatively, my belief that I ate cereal for breakfast, a belief that requires no argument, is entirely rational for me to hold.

Property – A characteristic or attribute of an object. For example, I have the property “having great hair.” Squares have the property “having four sides.”

Proposition – A statement that can be true or false. Not all statements can be true or false. Take the statement “Subscribe to our email list.” While you should definitely do that, that command is not true or false, it’s simply a command. Now take the statement “Alvin Plantinga is the most handsome man alive.” This statement is obviously true and so is a proposition. This short video explanation is also really helpful.

Reductio Ad Absurdum – Latin for “reduction to absurdity.” It’s an attempt to show that a claim is false by arguing that it leads to an absurd conclusion. For example, some people argue that their vote doesn’t count because they are just one person. Here’s a reductio of that claim: If everyone had that mindset, then no one would vote.

Reformed Epistemology – The thesis that belief in God can be rational and warranted without arguments. Check out our four-part series for an overview. See also: Evidentialism (Epistemology).

Religious Disagreement – The fact that people of different faiths have opposing beliefs about the nature of God, whether such a being exists, what our purpose in life is, whether there is an afterlife, and so on. Some philosophers have argued that religious disagreement ought to make us skeptical of religious claims full stop. That’s false, however.

Religious Pluralism – The view that all religions are equally true and/or valid. See this post for a refutation.

Rules of Inference – Logical rules that can be used to validly arrive at a conclusion in an argument. These rules include modus ponens, modus tollens, hypothetical syllogism, and others. See also: Validity.

Scientism – The view that the only real knowledge is scientific knowledge. Scientism is self-defeating–check out this recent book from J. P. Moreland. Also check out this series of blog posts from Ed Feser.

Seeming – A subject has a seeming when a propositions appears to them to be true. Intuitions are a kind of seeming.

Simpliciter – The Latin word simpliciter means ‘simply’ or ‘plainly.’ In philosophical contexts, it basically means ‘plainly, without qualification.’ For example, the statement: “I know God exists because I know it is true simpliciter,” is to say that, “I know, simply and unconditionally, that God exists.”

Sound – A deductive argument is sound if it is valid (ie: the conclusion follows logically from the premises) and the premises are true. See also: Valid.

States of Affairs – A state of affairs is a situation that either obtains or doesn’t. “Yoa Ming being more than seven feet tall” and “Hillary Clinton being the President of the United States” are both states of affairs. The difference is that the former obtains and the latter doesn’t. Note that states of affairs aren’t true or false–they either obtain or they don’t.

Street Epistemology – In short, Street Epistemology is atheistic evangelism. I recommend checking out our 3-part series explaining in detail what it is. Also check out our archive of posts tagged with ‘Street Epistemology.’

Teleology – Derived from the Greek word telos meaning goal, purpose, or end. The so-called “Teleological Arguments” for God, like the Fine-tuning Argument, are arguments from design.

Theism – In the context of Christian Apologetics, this term is used as synonymous with Generic Theism (see above). It’s the view that God exists and is all-powerful, all-knowing, all-good, and metaphysically necessary. The term can also be used more generally to mean that at least one deity exists.

Theistic Personalism – At the very least, Theistic Personalists reject the doctrine of divine simplicity, an essential component of Classical Theism.

Theology – The critical study of the nature of the divine. Christian theology is the study of Christian belief and practice–it has a heavy focus on the Old and New Testaments, as well as Christian traditions.

Truth – The traditional, or common, understanding of truth is that it is that which corresponds to reality (also known as correspondence theory). This is a central subject in philosophy and there are many different views. See Josh Rasmussen’s video for an overview of the different theories of the nature of truth.

Valid – A deductive argument is valid if it takes a form that makes it impossible that the premises be true and the conclusion false. In effect, an argument is valid if the truth of the premises logically guarantees the truth of the conclusion. Important to note: an argument can be valid even when the premises are false. Watch this short video for a more in-depth explanation.

Warrant – Alvin Plantinga defines warrant as the ingredient that turns mere true belief into knowledge. Not every true belief counts as knowledge. Suppose John suddenly found himself believing that there is a man named Goliath standing in Times Square. And suppose this belief happened to be true–at that moment there was a man named Goliath standing in Times Square. Does it makes sense to say John had knowledge? Not at all. So in addition to truth, knowledge requires warrant. What’s the best account of warrant? See this post.

Kinds of Reasoning

Deductive – A deductive argument provides a guarantee of the truth of the conclusion provided the premises are true. Here’s an example of a deductive argument: “All cameras take pictures. Nikons are cameras. So, Nikons take pictures.” If the first two statements are true, then the conclusion (what follows after “so”) is absolutely guaranteed to be true.

Inductive – An inductive argument provides a likelihood of the truth of the conclusion provided the premises are true. Here’s an example of an inductive argument: “Every day I wake up, the sun comes up. So, the next time I wake up, the sun will come up.” In this style of argument, there’s no absolute guarantee of the conclusion. Even though the sun has risen every day in my experience, that doesn’t mean it absolutely must come up tomorrow. Still, that conclusion is highly likely to be true.

Abductive -Also known as “Inference to the Best Explanation.” This kind of reasoning involves comparing two or more alternatives and deciding which is best. The “best” explanation will be the one that exemplifies the greatest number of explanatory virtues (like simplicity, explanatory power, explanatory scope, degree of ad hocness, and so on). Suppose the data to be explained is a bowl of cereal on the kitchen table. Here are two possible explanations: (i) your wife left it there momentarily, or (ii) an army of pink and purple aliens came down to Earth and placed that bowl of cereal in that exact spot in order to deceive you. Think about why (i) is the better explanation and you’re doing abductive reasoning!


A-Theory vs B-Theory of Time – The A-theory of time says that there is a real difference between past, present, and future. The present moment exists, but the future is just a potentiality. A-theorists are also committed to temporal becoming–things actually come into being and they go out of being. A-theory is the common sense view. B-theory, on the other hand, says that there is no real difference between past, present, and future–the past, present, and future are all equally real. The moment of your birth is just as real as the moment of your death. Everybody that’s ever lived still exists; they haven’t vanished into nonbeing. On B-theory, the common sense passage of time that we all experience is just an illusion of human consciousness.

Axiological vs Deontic Moral Properties – Axiological moral properties are more commonly known as moral values. Moral values have to do with goodness and badness. It is good to be a doctor, it is bad to be a murderer. Deontic moral properties are more commonly known as moral obligations. Moral obligations have to do with rightness and wrongness. It is right to help the poor, it is wrong to torture infants for fun.

Basic Beliefs vs Properly Basic Beliefs – A belief is basic when it is not held on the basis of any argument. My belief that I ate a sandwich for breakfast, for example, is basic. I simply think about it, remember that I had a breakfast sandwich, and then form the belief “I ate a sandwich for breakfast.” However, not every basic belief is properly basic. Properly basic beliefs are basic beliefs that are rational for a person to hold. Most would agree that no one is rational in holding the basic belief “my next gamble at the casino will make me a millionaire.” But, suppose I’ve just jammed my finger in the car door and find myself believing I am in excruciating pain. Hardly anyone would say my belief in this case is irrational. The latter is an example of rational basic belief, or a properly basic belief.

Contingent vs Necessary – A contingent being could have failed to exist. My camera is a contingent being. It didn’t have to be here. There’s a possible world, for example, where no one invents cameras. In that world my camera is non-existent. By contrast, a necessary being cannot fail to exist. Some philosophers believe that abstract objects, like numbers and mathematical objects exist necessarily–they exist in all possible worlds. The terms ‘contingent’ and ‘necessary’ are used as opposites. Anything that is contingent is not necessary–anything that is necessary is not contingent.

Lexical vs Real Definitions – Lexical definitions are determined by use. Real definitions involve a philosophical analysis of a term’s necessary and sufficient conditions. For example, the lexical definition of knowledge is something like justified true belief. However, a real definition of knowledge might involve concepts like externalism, proper functionalism, reliabilism, and so on.

Exegesis vs Eisegesis – Exegesis draws meaning out of a text, eisegesis reads meaning into the text. The former is good, the latter bad.

Exegesis vs Hermeneutics – Hermeneutics is the study of the principles of interpretation–exegesis applies those principles. Hermeneutics supplies the tools to discover a text’s meaning, and exegesis uses those tools.

Implicit vs Explicit Contradiction – Here’s an example of an explicit contradiction:

(1) Cameron is a photographer and Cameron is not a photographer.

Explicit contradictions are rarely articulated in real life. Most contradictions we are familiar with are the implicit sort. Implicit contradictions are explicit contradictions in disguise. For example, consider the following implicit contradiction:

(2) Cameron is a married bachelor.

This statement is clearly contradictory, but it’s not explicitly contradictory (so defined). But with some additional steps, we can turn this implicit contradiction explicit.

(3) If Cameron is a married bachelor, Cameron is a married unmarried man.


(4) Cameron is married and Cameron is unmarried.

Premises (2) and (3) above combine to form an explicit contradiction (this process is also known as “formal contradiction”). One thing to note, however, is that the additional premises (like (3) above) must be necessarily true–otherwise there’s no real contradiction.

Moral Ontology vs Moral Epistemology – If you’ve heard William Lane Craig defend the moral argument, you’ve likely heard this distinction. Moral Epistemology concerns knowing which moral claims are true. Here’s a false moral claim: It is always wrong to love your children. But how do we know it’s false? That’s a question of Moral Epistemology. This is also called Applied Ethics. The Moral Argument is compatible with a number of applied ethical theories. Moral Ontology concerns the grounding or foundation of morality. We know that it’s wrong to torture infants for fun, but what makes that claim true? What is the source of morality? Where do moral claims come from? These are all questions concerning Moral Ontology. This is also called Metaethics.

Moral Values vs Moral Duties – Moral values have to do with moral goodness and badness. It is good to be a paramedic, it is bad to be an assassin. Moral duties or obligations have to do with moral rightness and wrongness. It is wrong to murder infants (including fetuses), it is not wrong to love others.

Necessary Condition vs Sufficient Condition – A necessary condition is a condition that must be satisfied in order for some state of affairs to obtain. For example, a necessary condition of eating a bowl of cereal on Sunday morning is: having a bowl. Without a bowl, you can’t eat a bowl of cereal. A sufficient condition is a condition that, if satisfied, guarantees that some state of affairs obtains. So, a sufficient condition of eating a bowl of cereal this Sunday morning is eating a bowl of cereal every Sunday morning. If you eat cereal in a bowl every Sunday morning, then you are guaranteed to eat a bowl of cereal this Sunday morning. Note that eating cereal in a bowl is not a sufficient condition of eating a bowl of cereal this Sunday morning since you could eat cereal any day of the week.

Objective vs Subjective – A fact is objective if it’s true independent of anyone’s personal preferences. It is objectively true that Chimborazo is the tallest mountain on Earth. A fact is subjective is it’s truth is dependent on someone’s personal preferences. It is subjectively true (for me) that vanilla ice cream tastes better than chocolate.

Possible vs Feasible World – A possible world is a complete description of a way the world could have been. A feasible world is a possible world that could have been actual. According to Alvin Plantinga, not all possible worlds are feasible worlds. Suppose that God is a contingent being (he happens to exist in some worlds but not all). Then, there are possible worlds in which God does not exist; but those worlds aren’t feasible for God to create; God can’t create a world in which He doesn’t exist. A feasible world is a world that could have been actual.

Rebutting vs Undercutting Defeater – A rebutting defeater is a reason to think that some conclusion is false, whereas an undercutting defeater is a reason to think that some conclusion is unsupported. For example, suppose person A has told person B that her name is Judy. But then B learns that A is a habitual liar. This information undercuts A’s testimony. Even though A’s name could really be Judy, her testimony has been undercut by the fact that she is a habitual liar. That’s an example of an undercutting defeater–the conclusion could still be true but it is no longer supported by the evidence. Now suppose that person C, person A’s brother, steps in and says that A’s name is actually Mary. This is a rebutting defeater–C’s testimony is a reason to think that A’s claim is false, not merely unsupported. Note: C could add that he knows A is a habitual liar in which case we’d have both an undercutting and rebutting defeater.

Kinds of Possibility

Epistemic Possibility – That which is possible for all anyone knows. Anything that isn’t incompatible with what we know is epistemically possible. For example, even if you think aliens probably don’t exist, it’s compatible with what we know that they might exist–the existence of aliens is still epistemically possible.

See the following graph for a visual representation of the standard model of modality:

Logical Possibility – This is the broadest kind of possibility. Logical possibilities include any proposition that sheer logic leaves open, no matter how otherwise impossible it might be. Believe it or not, round squares are logically possible. To know that round squares are impossible, we need an additional necessary premise about the natures of squares and circles–we can’t rule out round squares on logic alone. This is a good article contrasting logical and metaphysical modality.

Metaphysical Possibility – Metaphysical possibilities are the logical possibilities that are also allowed by the natures of all of the things that could have existed. The nature of a circle, for example, is such that it couldn’t possibly be a square. So, round squares are metaphysically impossible. This is a good article contrasting epistemic and metaphysical modality.

Physical Possibility – Physical possibilities are the logical and metaphysical possibilities that are also allowed by the physical laws of nature. It is both logically and metaphysically possible that I travel at the speed of light, however, this is not physically possible. This is a good article contrasting metaphysical and physical modality.


AFR – Argument from Reason

CC – Capturing Christianity

CORNEA – Condition of ReasoNable Epistemic Access

CT – Classical Theism

DCT – Divine Command Theory

EAAN – Evolutionary Argument Against Naturalism

ECT – Eternal Conscious Torment

FT – Fine-Tuning

FTA – Fine-Tuning Argument

HADD – Hyperactive Agent Detection Device

KCA – Kalam Cosmological Argument

LCA – Leibnizian Cosmological Argument

LFW – Libertarian Free Will

LXX – Septuagint

MA – Moral Argument

MDCT – Modified Divine Command Theory

MEB – Maximally Excellent Being

MM – Mere Molinism

MGB – Maximally Great Being

MOA – Modal Ontological Argument

NT – New Testament; Natural Theology

OA – Ontological Argument

OT – Old Testament

PC – Phenomenal Conservatism

PF – Proper Function

PoE – Problem of Evil

PoH – Problem of Hiddenness

PoR – Philosophy of Religion

Presupp – Presuppositionalism; Presuppositionalist

PSR – Principle of Sufficient Reason

PvI – Peter van Inwagen

RA – Real Atheology

RE – Reformed Epistemology

RF – Reasonable Faith (William Lane Craig’s ministry)

Rez – The Argument for the Resurrection or “Resurrection” (depending on context)

SEP – Stanford Encyclopedia of Philosophy

ST – Skeptical Theism

TAG – Transcendental Argument for God

ToM – Theory of Mind

TP – Theistic Personalism

WLC – William Lane Craig


Learn these fallacies–learn what they are, how to spot them, and how to avoid them–but don’t just go around accusing people of fallacies. By that I mean, don’t look for opportunities to use these words. That’s a good way, in my experience, of ensuring your conversation won’t be productive. Instead, explain the mistake you see, in a respectful way, without using the technical term. Doing this has several benefits. First, you sound like an actual human being. Normal people don’t go around using terms like “non-sequitur” and “taxicab fallacy.” Second, when you explain how and in what way their argument is fallacious, they, and others watching, will be able to see that, yeah, so-and-so’s argument actually is fallacious.

Also worth noting: I don’t mention every fallacy out there. For a bigger list, check out this Wikipedia article.

Formal Fallacies

Affirming the Consequent – This fallacy takes the form: “If P, then Q. Q. Therefore, P.” Example: It is fallacious to assume that because your driveway is wet that it must have rained. Even though the conditional statement “If it rains, my driveway will be wet” is true, it doesn’t follow from the fact that your driveway is wet that it must have rained–someone could have wet the driveway with a hose, for example. Watch this video for an explanation.

Appeal to Probability – The fallacy of taking something as certain because it is probably (or possibly) the case. Watch this video for an explanation.

Argument from Fallacy – The fallacy of thinking that because some argument is unsound, the conclusion must be false. It takes the form: “If P, then Q. P is a fallacious argument. Therefore, Q is false.” This is a form of denying the antecedent. Watch this video for an explanation.

Denying the Antecedent – This fallacy takes the form: “If P, then Q. Not P. Therefore, not Q.” Example: If I am a photographer, I have a job. I am not a photographer. So, I don’t have a job. This argument is obviously mistaken. I could have any number of other jobs. Watch this video for an explanation.

Modal Fallacy – The fallacy of thinking that because something is true then it is necessarily true. Example: The President must be 35 or older. Donald Trump is the President. Therefore, it’s necessary that Donald Trump is 35 or older. This reasoning is fallacious because even though Donald Trump is President, and the President must be over 35, he was once younger than 35. This is the same mistaken reasoning that leads (some) people to believe that divine foreknowledge precludes human freedom.

Non sequitur – A deductive argument that is logically invalid. The term is used interchangeably with ‘formal fallacy.’ Any conclusion that doesn’t logically follow from the previous premises is a non sequitur. Watch this video for an explanation.

Informal Fallacies

Ad Hominem – The fallacy of focusing on the person instead of on the argument. It’s a fallacious argumentative strategy where genuine discussion of the topic at hand is avoided by instead attacking the character, motive, or other attribute of the person making the argument, or persons associated with the argument, rather than attacking the substance of the argument itself.

Appeal to Motive – The fallacy of challenging a claim by calling into question a person’s motives. A common feature of appeals to motive is that only the possibility of a motive (however small) is shown, without showing the motive actually exists, and, if the motive did exist, it played a role in forming the argument and its conclusion. Here’s a video explaining it.

Appeal to Novelty – The fallacy of thinking that a new idea is automatically superior or closer to the truth simply because it is more modern.

Argument from Ignorance – This fallacy asserts that a claim is true because it hasn’t been proven false (or vice versa). In common language it’s expressed by something like, “Well, prove me wrong!” Here’s a video explanation.

Begging the Question – The fallacy of assuming that the conclusion is true instead of supporting it. Assuming the conclusion is true begs the question: what reason is there to think the conclusion is actually true? Hume’s famous argument against miracles is a prime example of how even professional philosophers can end up doing nothing more than begging the question.

Bulverism – The fallacy of assuming your opponent is wrong and explaining their error. The Bulverist assumes a speaker’s argument is invalid or false and then explains why the speaker came to make that mistake, attacking the speaker or the speaker’s motive. The term “Bulverism” was coined by C. S. Lewis to poke fun at a very serious error in thinking that, he alleges, recurs often in a variety of religious, political, and philosophical debates.

Circular Reasoning – This happens when the reasoner starts with what they are trying to end with. Here’s another way of saying it: the only people willing the accept the premises are those that already accept the conclusion. Watch this video for an explanation.

Chronological Snobbery – The thought that ideas that are older are worse due to it’s being situated temporally in the past. The term was originally coined by C. S. Lewis.

Equivocation – The use of a particular word or expression in multiple senses throughout an argument leading to a false conclusion. Abbott and Costello’s “Who’s on first?” routine is a well known example of equivocation. Here’s another example: Feathers are light. Whatever is light can’t be dark. So, feathers can’t be dark. The term “light” is being used in two different ways. The first one mean light in weight, while the second means light in pigment.

Fallacy of Composition – The fallacy of thinking that because something is true of its parts, it must also be true of the whole. For example, it doesn’t follow that because every part of the elephant is light in weight, that the whole elephant is light in weight. Important to note here is that some inferences from parts to wholes are legitimate (e.g., if every brick is red, the whole wall is red).

Genetic Fallacy – The attempt at invalidating a position on the basis of how a person came to hold it. Here’s an example: arguing that John’s belief in a round Earth is false because he learned about it in a comic book. This fallacy happens all the time in the context of religion. Atheists sometimes argue that religious beliefs are false because they were acquired through arational means. This kind of thinking is fallacious on many levels.

Moving the Goalposts – Occurs when evidence presented in response to a specific claim is dismissed and some other (often greater) evidence is demanded. That is, after an attempt has been made to score a goal, the goalposts are moved to exclude the attempt. Here’s a video explanation.

No-True-Scotsman Fallacy – Occurs when one attempts to protect a claim from counterexamples by changing the definition in an ad hoc fashion to exclude the counterexample. Example – Person A: No Scotsman would put sugar on his porridge. Person B: But my grandpa is a Scotsman and he puts sugar on his porridge. Person A: Oh well then he’s not a true Scotsman. Here’s another example – Person A: All knowledge is scientific knowledge. Person B: Logical, mathematical, and ethical truths can’t be proven by science. Person A: Well then all real knowledge is scientific.

Red Herring – A new argument or claim that is made to distract from the original topic at hand. Here’s a video explanation.

Shifting of the Burden of Proof – The burden of proof is very simply on the person that makes a claim. Shifting of the burden of proof occurs when someone making a claim requires others to prove her claim is false. It’s a form of an argument from ignorance (e.g., “If you can’t prove my claim is false, then it must be true).

Special Pleading – A form of argument that involves an attempt to cite something as an exception to a generally accepted rule or principle without justifying the exception.

Straw Man – This fallacy occurs when person A asserts an argument and person B refutes a different, much easier to attack argument. Straw men are meant to look like men, but aren’t actually men. Similarly straw men arguments are meant to look like the original argument, but aren’t actually the original argument. This is one of the most common fallacies. Watch this video for a longer explanation.

Taxicab Fallacy – Let me note that this fallacy is really only used in the context of Christian apologetics, so it’s difficult to nail down. It is roughly the fallacy of accepting a claim or principle up until you’ve reached your desired destination. It’s a claim of inconsistency. For example, some atheists hold that all contingent things have explanations up until they arrive at the universe. They see where the argument is going (to God) and hop out right before.

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