I have lately been periodically annoyed by people failing miserably at using words. I have been a non-figure in the atheist community for several years. My voice doesn’t (and shouldn’t) count for much, but I’ve certainly read enough to define key ideas. So I decided to apply my limited expertise and put together a limited glossary of terms as I have seen them actually used in situ. In some cases (and this might be most of the point) I have included ideas with which a particular entry is logically incompatible. And because I science for a living, I have allowed some relevant terms to slip in.
Abiogenisis– The process by which increasingly complex assemblages of molecules develop the ability to replicate and decrease their own entropy (by using energy to pump entropy into their surroundings). Logically incompatible with special creation and intelligent design.
Agnosticism– The belief that evidence does not entirely either establish or eliminate the existence of gods. Note that either an agnostic or a gnostic may be either atheist or theist. The two beliefs are wholly independent (good explanation in graphical form may be found here).
Atheism– A lack of belief in gods. Although the term atheist may be properly used to denote a person who makes the positive claim that there evidence against the existence of gods, one need not go so far to be an atheist. The word only implies the lack of belief. Logically incompatible with gods and any religions based on such entities.
Evolution– The established scientific theory linking genetics/molecular biology, ecology and development into a cohesive whole. This is not the beginning of life, but rather the set of laws governing the changes over time and stability of established life. Logically incompatible with special creation and intelligent design.
Freethought– The rejection of dogma. Superficially compatible with religion (since freethought makes no particular claims), but logically incompatible with most organized religion. Often paired with skepticism and often results from reading the dogma in question.
Humanism– The belief that humans have intrinsic value, at least to other humans. The prioritization of human interests in the observable universe is typically as a basis for ethics. Often but not always paired with secularism. Logically incompatible with supernatural ethical systems, but not always incompatible with religion per se.
Islam– A religion based on a single god and the writings of Muhammad, believed to be the most recent prophet of that god. I only put this on here to point out that it is logically incompatible with atheism. Seriously, I promise it’s not compatible.
Science– The systematic process of establishing knowledge about the world by:
1) Making predictions based on putative facts
2) Attempting to disprove those predictions through experiment
3) Explaining them in the context of other established facts
Scientific ideas are placed in a hierarchy (although not all ideas fit neatly) according to their progress in the overall process:
1) A hypothesis is an idea which is compatible with other established facts, but has not been adequately tested. In order to be valid, a scientific hypothesis must be falsifiable- that is, in the event that the hypothesis is false, some experiment is possible which will prove it to be false. Rejection of a hypothesis requires that it disagree with data.
2) A law is an idea that has been well tested and shown to make reliable predictions of limited scope. In order to be valid, a scientific law must both define it’s scope and make accurate predictions within that scope. Typically laws are formatted mathematically or in something easy to translate into formal logic.
3) A theory is a cohesive explanation of a group of interrelated laws which can make predictions of broad scope. In order to be valid, a scientific theory must be based on valid scientific laws and must either simplify those laws or expand the scope of those laws. For example, evolution allows us to make predictions about allele frequency (a genetic question) based on ecology.
Theory (particularly if use of an indefinite article is neglected) may also refer to the body of mathematics and logic which underlies a particular scientific discipline. When we refer to a prediction as true ‘in theory’ (tail fins should make the rocket’s path straight) it is typically in this sense, which often differs from ‘in practice’ due to incomplete or erroneous knowledge of starting conditions (I swear I didn’t know the tail fins were flammable!).
Science is not logically incompatible with most religious ideas, but is often at odds with them. This is because religious ideas are often not falsifiable. An invisible omnipotent figure that wants you to believe in it without evidence can always hide behind the idea that it is omnipotent and hides all the evidence. However a scientific attitude requires claims for which no disproof is (at least in principle) possible not to be considered legitimate claims about the world. Consequently, science will never provide such claims with any sort of validation.
Secularism– The belief that religion/religious considerations should be ignored or rejected. Occasionally denotes a more limited secularism, applicable only under certain circumstances (e.g., government functions).
Skepticism– Doubt in the absence of either rational proof or empirical evidence. This is not doubt in the face of evidence or the use of absent evidence to assert the alternate position of a dichotomy (often termed pseudoskepticism). Logically incompatible with faith or ‘other ways of knowing’.
I may decide to add to this later or I may not. I will also consider corrections but if your only contribution is copy/paste from a dictionary, don’t be surprised when I ignore you.