Is it possible to define rationality, reason, or logic without using the other two?

I was explaining to a coworker how we atheists valued rationality over faith and his response was to ask me what rationality was.

I feel that I understand it well enough personally but I need a better definition to serve as an explanation for my coworker than that found in Websters.

Websters definition was either self referencing (Rational to reasonable to logical to rational) or almost entirely subjective (described as correct or good).

That I really do not think will go very far with a faith head who will have an entirely ready made response of “What could be more correct or good than gods will.”

Thank you very and any help will be much appreciated.

Posted: March 10th 2008


A very wise man once said:

you cannot rationally argue somebody out of a position that they did not reach rationally in the first place

People who have irrational beliefs lodged in their heads may not be able to discuss them rationally, so you may be in for a waste of time. Not to mention discussion religion with co-workers can be pretty volatile and divisive.

Having said that…

For me, it is a question of what evidentiary standards you use to decide what to believe in.

The vast majority of theists believe in god – and in a specific version of god – because that’s what they’re parents believed – they were told when they were very young their particular beliefs, and have held them since then.

Believing something merely because somebody tells it to you is not a rational belief. Rational beliefs are built on evidence.

The problem you will run to is that everybody thinks all their beliefs are rational. It’s obvious that God exists because of and and .

That takes you into the realm of christian apologetics – reasons for belief – which I encourage you to study.

Posted: March 16th 2008

See all questions answered by Eric_PK

George Locke

For the purposes of your discussion with your coworker, the relevant issue isn’t the definition of rationality per se, but differentiating it from faith.

The differences include:

  • reevaluation of one’s position based on new evidence
  • basis in recent observation rather than texts compiled by committee more than a thousand years ago
  • valuing repeatable tests over personal gnosis

I think overall, it’s not important that you convince your coworker. The important thing is that you engage his intellect. If you can convince him that your position isn’t total bollocks then that’s a small but practical victory.

In general, if you’re talking to an otherwise reasonable person who happens to hold faith-based beliefs that you consider irrational, it’s much easier to show him that his isn’t the only defensible position around than to try and convince him that his opinion is indefensible. Instead, show that your beliefs have a basis in fact, and this will show him that you’re not crazy. A reasonable person tries to draw his own conclusions, and if you can show him that there are other conclusions he might draw then that is a victory for rationalism.

Posted: March 14th 2008

See all questions answered by George Locke

John Sargeant www

Rationality is the efficient means or process by which you draw a conclusion in thought or action that achieves an accurate end. For example if you wanted to buy shoes it would be irrational to attempt to buy them at a solicitors office; if you wanted to understand germ theory you would not read the bible.

Reason is where an argument or idea can be demonstrated to be based on observable principles, concepts or evidence. For example John Rawls’ distributive principle. It is in this sense a judgment that can be proven to be a fact (positive) or be a value judgment (normative).

Logic is in comparison much more tight – it sets the ways in which a theory can be deduced, in an attempt not to lead to a false conclusion. In effect it is the rules of the game within a field of inquiry.

The three together used in an argument in many ways force someone to keep themselves honest – it does not allow a trump card like faith to sink a discussion or personal feeling to win the day over another view.

Posted: March 13th 2008

See all questions answered by John Sargeant

SmartLX www

You’d do a lot better on the Wikipedia page than in a dictionary.

A good working definition for your purposes is that rationality is an ongoing effort to make sensible judgements and decisions based on logic (sorry, but deductive/adductive/inductive logic is very clearly defined and should be included), probability, experience, evidence and to some degree emotions. I hesitate to add emotions because some religious people regard God as an “emotional truth”, but emotions can be necessary to determine who may be hurt or helped by an action.

Importantly, all of the above bases for rationality should be considered together if possible. Someone who claims they’ve had a vision of Christ is making an argument from personal experience with great emotion, but lacks evidence and is making a very im*probable* claim, to make a contrary example. The elements of rationality are differently weighted, so some outweigh others. The majority often decides.

Once you’ve broken down the nebulous concept of rationality into better-defined components like evidence, logic and probability, you’re on a much better platform to argue that faith is not supported by these things. You will still have an argument on your hands as the whole point of apologetics is to argue that faith is thus supported and is therefore rational. However it’s an argument theists have never won, despite centuries of effort and almost unlimited personpower and resources.

As Logicel said, have fun.

Posted: March 12th 2008

See all questions answered by SmartLX


Rationality is one of those useless words in common usage, like lazy — the meaning varies from speaker to speaker. Hopefully, some writers for this site who are well conversed in Philosophy will have a go at the specialist’s definition of rationality.

I do not use rationality as a basis for presenting my non-theistic case. I use instead the lack of evidence for the supernatural.

If pressed about that aspect, I emphasize that rationality is often conflated with rationalizing. The latter is when we already have decided on an outcome without adequate evidence, for example, there is a God who watches our every move and has a purpose for each and every one of us (or a divine teapot is orbiting earth), we are as beautiful as Angelina Jolie, there is an invisible man following us, etc., resulting in an awkwardly contrived pile of 'reasons’ to support our rather wobbly conclusion. Conversely, the smallest number of reasons is often indicative that one is truly being rational, per Occam’s Razor.

Being rational is availing yourself of critical thinking (not critical theory, which is presenting a neutral point of view, that is, presenting both sides of an issue). Critical thinking is when you demand evidence for a premise, and the corollaries resulting from such a premise do not contain fallacies. Critical thinking is when you can hold two opposing ideas and remain undecided about them until you have enough evidence to proceed with any actions based on those ideas.

I suggest you write up a dialog between you and your theist friend. Try your arguments out on paper (or on the computer!) first. Experiment, play around, and have some fun!

Posted: March 12th 2008

See all questions answered by logicel


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