Defining "faith" here as "the belief in something without needing or even in spite of a persuasive empirical case." Therefore believing in Germ Theory is not an article of faith, but believing in a God, or ghosts, or reincarnation, or heaven, or karma, is.
(Notable aside: I've seen it suggested that the word "saddha" which often gets translated "faith" in English is closer to "confirmed confidence" in meaning. This means that "saddha" refers to the kind of faith we have that rain is caused by condensing water vapor, rather than the kind of faith we have that rain is caused by cracks in the firmament.)
Dharma practice is good, because it's a set of tools to accomplish certain things. The rest is there basically for explanations and examples. Dharma practice is a process that can do some good for just about anybody. However, the things that Buddha taught which are actually tools to advance and improve oneself (4NT and the 8FP) don't require the practitioner to believe anything that flies in the face of evidence.
Lots of Buddhists say that Buddhism requires faith (in reincarnation, in metaphysical "what goes around comes around"-style karma, in bodhisattvas, etc.) but doesn't require blind faith. Frankly I've heard the same statement from followers of the big monotheist traditions which nevertheless require adherents to build their lives around assertions like "there's a wish-granting moody man in the sky who likes you best." People who believe this don't believe they're being irrational or believing things which fly in the face of evidence, and I don't see the people who believe in things like karma or rebirth to be all that much different.
Not everybody who has an opinion about a subject has an opinion because of "faith," but everybody who believes something supernatural, superstitious, or otherwise metaphysical most certainly does, because there's no empirical support for the existence of those things (or it wouldn't require faith to believe in them). As a result, "faith" (which is always blind wishful thinking, imo) plays a large role in a lot of people's dharma practice, but not in mine.
After I explain this, I often run into a few questions/objections (more the latter, since people of faith seldom think to ask me anything), and rather than go through this conversation again for the millionth time, I'm just gonna post the FAQ and hope that it saves a little labor for all of us.
OBJECTION ONE: "But there is no truth but personal truth, and nobody has the REAL answers, so one answer is as good as another, right?" (AKA Argument from Postmodernism)
The common question at this point is "what is evidence?" "What kind of evidence can you find which isn't subjective and on some level taken on faith?" I say it's a common question because I've had some of the same conversations with Buddhists now that I have had with Christians on this subject, and since it always comes up eventually, I'd better just address it.
It's occasionally an interesting thought experiment to say "nothing is objectively true, there is no reality outside of our perception of it, and there's no such thing as truth," but it's not particularly useful in the here and now. When I ask my doctor whether I'm sick because of a bacterium or a virus, this viewpoint is not useful. When I ask my partner whether we have enough money to cover our expenses, this viewpoint is not useful. Why? Because these are practical questions.
Questions of suffering are practical questions. This is why I often refer to my particular path as "dharma practice" and not "Buddhism." I've seen too much suffering caused by belief systems that come packaged with beliefs that must be taken on faith for it to seem plausible that yet another one is the solution.
Until anybody who believes in karma or rebirth fulfils their burden of proof and persuades me, I'm not going to live as though they're true. Why? Because I have actual problems to solve in my actual life, and I can't do this unless I'm only factoring in things which are likely to be true. Considering that the tools of dharma practice that Buddha laid out deal with actual problems for my actual life, I see no reason to distract myself by clinging to past lives or yearning for future ones. I see no reason to worry about them at all. Aren't we, as Buddhists, supposed to be living in the present and aware of what's going on around us now?
OBJECTION TWO: "But everybody has faith in something." (AKA Argument from I Know You Are But What Am I)
First off, see the beginning of this little ramble. If my answer to this isn't already clear, then I'll elaborate, becaue this one is actually a big pet peeve of mine.
On a personal level, I honestly find it rather distasteful to muddy the discussion by referring to everything that everybody gives weight to as "faith." I don't have "faith" in Germ Theory the way my dad has faith in Jesus. I don't have "faith" in natural selection the way some people I know have "faith" in Young Earth Creationism. By the same token, I don't have "faith" that I'm capable of disciplining my own mind the way that some Buddhists have "faith" that praying to a Bodhisattva will acquire them merit.
I think the difference between "faith in Jesus/reincarnation/etc." and "faith that gravity pulls objects toward the center of the Earth when we are standing on its surface" has been adequately covered earlier in the thread. After a while discussing this issue with various people in various places, it's starting to seem to me that the people who say, "well, everybody has something they take on faith" are either deliberately fudging the way evidence-based beliefs are formed so that they cease to seem different from articles of faith, or they don't actually understand how people form opinions without faith-based assumptions.
I'm going to argue again that belief in things without (or even despite) evidence is a bad idea, because we have more than enough problems in the real world to think we're going to solve anything by starting with a misapprehension of the conditions around us. We're not going to solve human suffering by inventing superstitious ideas about the sources or implications of suffering any more than we can cure disease by inventing superstitious ideas about how it spreads or its symptoms.
I don't mean to be harsh, but it's sort of a pet peeve of mine when people say, "Oh, well, everybody takes things on faith." It may serve to smooth over differences by implying that we're all doing the same thing when it comes down to it, but it's unfortunately demonstrably untrue, and lasting peace and tolerance can't be built on that sort of friendly dishonesty. I'd much rather believers think I'm strange and overintellectualizing and missing the point than have them be friends with a figment of me and my path that I don't really recognize.
Again. A lot of people make use of faith. However, it is extremely important to note that not everybody does. Assertions to the contrary don't help people get along despite their differences any more than misapprehensions about any other part of our human experience. Faith plays a large role in many peoples' Buddhist practice, but not in mine.
OBJECTION THREE: "Well, there are just some questions that aren't for reason and rationality to solve." (AKA Argument from Inapplicability of Arguments)
Dear Humanity: Stop conflating faith and confirmed confidence. These two things can only be conflated if you do one of the following things:
A. Create separate categories for things which may be decided upon with faith-based reasoning, and which must be decided upon with empirical thinking. For example: Most people (though not all) place medicine in this category. They'll pray for recovery, but they'll take antibiotics as well.
B. Allow faith to subvert empirical reasoning all the time. The Church of Christian Science is one big one. They'll pray for recovery, and be insulted by the suggestion that they need antibiotics as much as they need the protection of the Lord.
Option A seems to imply that there are questions which are "safe" to apply limited critical thinking and empirical examination to, and questions for which that's not good enough. I say that even that much faith is too much faith, because if you have to exclude something from the most important decisions, then it probably isn't helping the lesser ones either.
Again. Finally. In summary. Etcetera. Faith is wishful thinking. Period dot. Nothing I've read of the Buddha suggests that he thought very much of wishful thinking as a problem-solving tool. This doesn't mean that it has no place in Buddhist religions or cultures, but it does mean that it's probably something of a departure from what Buddha himself actually suggested. Furthermore, Buddha's opinion aside, there's nothing that suggests to me that it'd be worth including at all, which is why (once again) I don't.