From Plato's Cave to Descartes' Malignant Demon to the Wachowski brothers' virtual world of the Matrix, our assumptions of what we know (and think we know) about "the real" continue to be challenged. I've studied epistemology extensively, and I still can't quite tell you exactly how I know what I know, or what I know, or whatever. And I think we're all pretty much in the same boat. Herein lies the importance of critical thinking. A critical thinker holds her beliefs with an open hand, and doesn't stop examining, questioning, and studying, and doesn't assume that she's figured out all the mysteries of the universe, because she wants her beliefs to conform to reality as much as possible. A critical thinker bases her thoughts and actions on the best explanation of the evidence, requiring the application of logic, and the use of reason.
I see a very important distinction between belief and conviction, and more people need to see it as well. Belief and conviction, while related, differ significantly concerning the need for evidence. Skeptics will commonly uphold the idea that one should have good reason (i.e., a reason for belief based on logic, evidence, and the best explanation of the data) to believe something. Generally, I think this is true. Why believe something if you have no good reason to believe it? But there are some things we believe which (I contend) we may believe without requiring sufficient evidence. Consider two guys: Bill and Ray. Bill believes in the existence of aliens. Ray believes that one day humans will figure out how to safely travel the speed of light like in Star Wars. Does either of these guys have sufficient evidence to warrant their respective beliefs? I would argue that they are basing these beliefs more on a "hunch" or a "gut feeling." That's not to say there's no reasoning at all behind their beliefs. Bill might consider how enormous the universe is and how little of it we've been able to study, and based on this fact, coupled with his understanding of how life evolved on Earth, he could understandably come to believe that there are (or were) lifeforms of some sort elsewhere in the universe. Likewise, Ray might consider the fact that our scientific understanding and technological advancements are increasing at an exponential rate, and base his belief on the thought that it's only a matter of time before we figure out how to travel at lightspeed.
But what if these beliefs became convictions? Belief is a mental attitude of acceptance or assent toward a proposition: "I think this is true." We don't always have control over what we believe, and we don't always hold on to beliefs strongly or dogmatically. Conviction, on the other hand, is firmly held belief that prompts one to action. All convictions are beliefs, but not all beliefs are convictions. Imagine if Bill's belief in aliens turned into a conviction that motivated him to spread the word about aliens, and try to convince other people to believe as he does. Imagine further that, as Bill proselytizes, he judges and condemns anyone who doesn't believe in the existence of aliens. Imagine yet further that Bill alters his lifestyle to accomodate the day when aliens will visit our planet. He builds a spare room for the aliens when they arrive. He refuses to date or marry someone who doesn't share his belief in aliens and his hope in the great and glorious Day in which the aliens will come to earth and show us the way to enlightenment. Now, Bill's otherwise harmless and perfectly okay belief in aliens has become completely irrational, not because the evidence has changed, but because this unjustified belief, rather than merely serving as a form of emotional or psychological relief or satisfaction, has become a foundation upon which Bill has based his life, attitude and behavior: a foundation lacking proper rational support.
When an unjustified belief becomes a conviction, since the belief rests on a foundation that lacks support, the conviction will likely lead to further beliefs or doctrines - matters of both orthodoxy and orthopraxy - that are even more irrational than the initial conviction. The history of religion is replete with examples of this. Belief in god, based on faith or personal experience or something like, as William Lane Craig says, the "inner witness of the Holy Spirit," or other such non-rational foundations, has taken otherwise well-intentioned people and led them into holy wars, bigotry, hatred, judgmentalism, mass suicides, the denial of science, "God Hates Fags," racism, the justification of slavery, The Inquisition, the oppression of women, the indoctrination of children, genital mutilation, the rejection of medicine in favor of prayer to cure illness and disease, and bad rock music - just to list a few examples.
Let's say someone believes in god (however that person chooses to define the term). Fine, believe that. I don't care. When this person then turns that belief into a life-changing conviction, that's where doubts arise concerning whether there is sufficient warrant to justify that conviction. I've seen believers base who they marry, where they go to school, how they spend their free time, what they do for a living, how they raise their children, who their friends are, et cetera, on (primarily religious) beliefs they cannot defend intellectually. What's worse, when someone with such conviction judges, condemns, belittles, or (as we've seen throughout history) persecutes those who do not share those beliefs, the amplitude of the believer's irrationality is seen in its entirety. An agnostic would contend that intellectual warrant simply does not exist to hold on to exclusively religious beliefs with life-changing conviction. Any religionist who desires to walk the path of a critical thinker must face this issue. Basing important life choices on beliefs held on faith, or a "gut feeling" or some sort of personal experience - even experiences so emotionally satisfying that they leave someone feeling so confident that her beliefs are true - is not rational.
Once the distinction between belief and conviction is understood, I think a further distinction must be drawn; namely, between belief and suspicion. By "suspicion" I mean an inclination toward thinking something is true, but not necessarily full-fledged belief or intellectual assent. Considering Bill and Ray once again, perhaps referring to their beliefs as suspicions - i.e., they suspect that their respective propositions are true - is more accurate. People do this all the time. Bill might suspect that O.J. Simpson did in fact murder his wife. Ray might suspect that the Chicago Cubs will never win a World Series in his lifetime. Bill and Ray may not have conclusive proof to support these inclinations, but I wouldn't consider either person irrational for holding such a suspicion.
This blog has been from the beginning a way for me to emphasize and defend the importance of critical thinking and basing one's thoughts and actions on logic, reason, and evidence. One of the first topics I wrote about on this blog dealt with belief apart from proof. While my thoughts on the distinctions between suspicion/belief/conviction had not yet been clarified as clearly as they are now, the general idea was there from the beginning. My thoughts then reflect my thoughts now vis-à-vis critical thinking and rationality: I contend that holding a belief apart from proof is in itself not diametrically opposed to a life of truth-seeking, freethought or critical thinking. Believing "just because that's what I believe" is intellectually neutral. Belief runs contrary to critical thinking when:
1. one refuses to subject her belief to rational scrutiny and critique;
2. one refuses to examine the evidence against her belief;
3. one refuses to examine the evidence for opposing beliefs;
4. one refuses to examine said evidence objectively;
5. one claims to possess knowledge and proof when in truth she has neither;
6. one is in love with her paradigm too much to change it;
7. one continues to ignore overwhelming evidence in order to keep her belief;
8. one believes her belief is true because she believes it;
9. one acts with deep conviction on a belief for which she has no evidence.
(This is not an exhaustive list, but should suffice for the purposes of this entry.)