*Technically, Hume and Laplace are contemporaneous, but Laplace did not complete his most immediately relevant work, showing the natural dynamic stability of the solar system, until after Hume's death.
Taken as just a label, anyone who doesn't believe that a god exists is an atheist. But as a member of a more-or-less cohesive social group, I find myself being more and more irritated with non-thoroughly-skeptical atheists. Non-thoroughly-skeptical atheists may be (at times) enemies of my enemies, but they are not necessarily my friends. Every now and again a non-thoroughly-skeptical atheist will wander into the the atheist social group I'm a member of, and I find myself really wishing they would go away.
But, to be honest, non-skeptical atheists seem rare. I know a lot of atheists, and I know very few non-thoroughly-skeptical people who make a point of self-identifying as an atheist. I've found that many non-thoroughly-skeptical people who don't believe any god exists typically explicitly disclaim self-identification as an "atheist" precisely because of the thorough commitment to skepticism in the atheist community. Even though they don't believe any god exists, they don't want to subject all their beliefs to skeptical inquiry; they feel that self-identification as an atheist would entail that they would have to commit to thorough skeptical inquiry. And perhaps they're right.
I personally do indeed have a thorough commitment to skepticism. I subject all my beliefs to skeptical inquiry. More importantly, I do my best to think about the world in thoroughly skeptical terms. I want to eliminate not only outright falsity but also bullshit — ideas about reality that are unfalsifiable and therefore not susceptible to skeptical inquiry — from my thinking about the world.
I think that the elimination of bullshit is where the atheists are leading the "skeptical" charge. Many skeptics focus on outright falsity, in fields such as medicine, global warming, evolution, and scientific inquiry in general. Good for them; I unreservedly support their efforts. But I think the elimination of bullshit is just as important as the elimination of falsity. If you're making a statement about reality that cannot be subject to skeptical inquiry, you're making just as much of an error as making a statement about reality that skeptical inquiry can determine to be false.
There are two reasons I take this position. First, any statement about reality can be recast outside the domain of skeptical inquiry. The most obvious example is the idea that one's "attitude" affects the outcome of experiments. Homeopathy, one might theorize, works only if you believe it works. If you're even "undecided", your attitude will actually affect the results, creating the illusion that it doesn't work. And, of course, if you try homeopathy and it doesn't work, then we can infer that you had "doubts", which undermined its effectiveness. Skepticism in general suffers from under-determination; we have to add explicitly philosophical components to skepticism (e.g. Occam's razor, equivalence, and provisional acceptance) to get skepticism off the ground. To commit to skepticism, one must commit not just to the authority of experiment and perceptual experience, but also to these philosophical components.
More importantly, though, bullshit — especially religious bullshit — is employed most often to talk about ethics in terms of talk about objective reality, the reality outside the minds of humans as conscious beings. Ethics, then, becomes a "scientific" endeavor rather than a "political" endeavor, an endeavor where people can be fundamentally mistaken. But you just can't talk about ethics in scientific terms, in the same kind of language we talk about objective physical reality. Skepticism at the philosophical level demands that we call all this ethics-as-reality talk as not falsity but bullshit.
We can see examples of ethics-as-reality talk actually motivating people to make false claims about reality to support their ethical principles. For example, many people ethically opposed to abortion claim that abortion causes breast cancer. Many people ethically opposed to gay marriage similarly make false or misleading scientific claims. For example, Catholic Answers' article, Gay Marriage, cites Paul Cameron, whose work has been criticized by both the American and Canadian Psychological Associations; in August 1996, the Canadian Psychological Association stated, "Dr. Paul Cameron has consistently misinterpreted and misrepresented research on sexuality, homosexuality, and lesbianism..." When bullshit comes through the door, falsity is rarely far behind.
Applying skepticism only to actually false claims about reality fatally weakens skepticism itself, by denying the philosophical components of skepticism. If a "skeptic" approves of holding one unfalsifiable belief about reality, why not another? Why would such a person not approve then of holding all of one's beliefs about reality as unfalsifiable claims? Because of under-determination, all claims about reality can be cast in unfalsifiable terms.
Skeptical atheists, by subjecting religion — the most venerable and wide-spread form of bullshit known to humanity — to skeptical scrutiny are the most vigorous promoters of thorough skepticism.