(intro music) My name is Sally Haslanger, and I'm a professor of philosophy at MIT. Today, we're going to discuss an argument in favor of atheism, in favor of the belief
that God doesn't exist. Let's start with some definitions. "Theism" - that's "the
belief that God exists." So, "atheism": "the belief
that God doesn't exist." Rational theism is one form of theism. It's the belief that there
are evidential reasons to believe that God exists. Now, arational theism is the
belief in God without evidence. There are plenty of people
who are arational theists, because they believe
in God based on faith. Faith is often thought
to be believing something in spite of the fact that you
don't have evidence for it, and it's completely common for people to believe things without evidence, right? We believe things all the time
based on wishful thinking. We believe it because
it's just in the air, or it's convenient for us to believe it. It makes us happy for us to believe it. All those sorts of things. But we're talking here about evidence, where "evidence" is "some information "that lends credibility to the claim, "in the sense that it's
more likely to be true "if you have the evidence." Okay, so arational theism, as I said, is a common position, but we're not really gonna
talk very much about it today. Irrational theism is the belief in God in spite of evidential
reasons supporting atheism. Notice that this is quite
different from arational theism. The belief in God without
evidence, as mentioned, could be just on the basis
of a lack of evidence. But irrational theism is
when you hold belief in God, that is, when you hold theism, but there are clear supporting reasons for the opposing view,
that is, for atheism. Now, that's problematic,
and we're gonna look a little bit further into
why it's problematic. Let's move on to a few more definitions so that we're clear what
we're talking about. "Contradiction" - what is a contradiction? A contradiction is when
you have a set of beliefs that are not possibly true together. So a set of beliefs is
contradictory if and only if it's not possible for
all of them to be true. Here's a simple example: "Today is Monday. It's not the case that today is Monday." Those can't both be true together. Now, we're making an assumption: mainly, that we're talking about
right here right now. We're not talking about something on the other side of the dateline. Considering "today is Monday," and "it's not today is Monday," that's a contradiction. Both of them can't be true. So if you believe both of them, then you're believing a contradiction. Now, it's not necessarily the case that a contradiction needs to
involve only two statements. It can involve three statements. So "all birds can fly," "penguins
are birds," "penguins can't fly." Not all of them can be
true together, right? If you hold what it is to fly stable, if you hold what it is
to be a bird stable, then you can't hold all these together and have just true beliefs. One of them has got to be false. Now you could say, "Well, maybe it's not the
case that all birds can fly," or, "Maybe it's not the case
that all penguins are birds," or maybe you could come
up with a modification of what it is to fly so
that penguins can fly. They're really good
underwater, for example. You watch them under water,
they look like they're flying. But that's not really flying. So you can't hold all of these beliefs. You have to figure out which
one you're going to give up. Likewise, "today is Monday" and "it's not the case
that today is Monday" - you need to give one up. Okay, now why do you have to give one up? Some people say, "Wait, we believe in
contradictions all the time. "It's just not obvious that
we believe in contradictions." Well, that's true. We probably do have contradictory beliefs, but it's not good to have
contradictory beliefs. We want to get rid of our
contradictory beliefs. Now there are a couple of reasons why. First of all, it's really
good to have true beliefs. You don't want to go around
the world having false beliefs, cause it gets you into trouble. So if I believe that there's no wall here, and I go walking into the wall, then that's not so good. False beliefs can get you
into trouble in that way. They can lead you into
problematic circumstances that you'd probably best not be in. So holding beliefs that
are false is problematic, and if you hold contradictory beliefs, you know one of
them has got to be false, and that's bad. Another thing is coherent action. Having contradictory
beliefs makes it difficult to act coherently. Look at this one: "Today is Monday, and it's not
the case that today is Monday." Suppose you have a dentist
appointment on Monday. What do you do? Do you go or not? You both believe that it
is and it isn't Monday, so what are you gonna do? It's hard to act coherently
and act in a sensible way to fulfill your obligations, etcetera. Since one of the beliefs you
hold has got to be false, and you can't act on two
contradictory beliefs, you can't really act coherently. So we're talking about whether God exists, and evidence for and against
the existence of God. Now, there are many different
conceptions of God or gods. I'm not trying to
adjudicate what's the right or best conception of God. But there's a particular
standard definition in the West, that God is an all-perfect being, a being at least who has
these three features: a god is all-knowing
(which is to be omniscient), all-powerful (which is to be omnipotent), and to be wholly good (or omnibenevolent). So this being is perfect, is omniscient, omnipotent,
and wholly good, (or omnibenevolent). We're gonna call the combination
of these features "OOO" ("O-O-O") because they're pretty
good ooo features. Let's go ahead and now
look at the argument that suggests that atheism
is the rational view to hold, the one that there's the
greatest evidence to believe. Here's the first premise: if God exists, he, she, or it would be OOO. Now I use "he, she, or
it" because, of course, I don't know whether there's a God, and if there is, whether
it's a he, she, or it, or at least for the
purposes of the discussion, we're not gonna assume anything like that. Okay, so that's the first premise. Second: if an OOO god exits,
there would be no evil. Well, why's that? Well, if a god were all-knowing, then that god would know
when evil was going to occur (or that it occurred), would have the power to make it not occur, and is wholly good, so would
also have the motivation to make it not occur. So this combination of
omniscience, omnipotence, and omnibenevolence suggests
that if a god were truly OOO, there would be no evil. We assume for the purposes
of argument that God exists. And we conclude, then, there is no evil. So if God exists, he,
she, or it would be OOO. If an OOO god exists,
there would be no evil. God exists, so there is no evil. The problem is, there is evil. Well, at least, it seems there's evil. That might be one of the
questions that comes up when we consider
objections to the argument. It appears, certainly
appears, that there's evil: lynching, terrorism, the
death of innocent babies. So for the moment, we're
gonna say there is evil. But look: "there is no evil," "there is evil" - this is a contradiction. And so we have to reject
one of these premises. Well, this one, that God is OOO, that one is hard to reject because that's just how
we've defined what God is. This one - it seems straightforward. And so once we assume God exists, and we assume that there
is evil in the world, which is hard to deny,
we get a contradiction. So we have to reject something. And so the thing that's
most likely to be false, according to the
argument, is number (3), that God exists. So we conclude that God does not exist. Now this argument is a
little bit truncated, as any argument is. It relies on two further assumptions. First, a wholly good thing
always eliminates evil as far as it can. And second, that there
are no limits to what an omnipotent thing can do. But these just seem to be
part of the definition of all-knowing, all-powerful,
and wholly good. It's just true by definition. So here's a way to think about it. If we assume a certain
kind of God, an OOO God, and we really take seriously
the perfection of that God (all-knowing, all-powerful,
omnibenevolent,) then once we assume that kind of God, and that there exists
some evil in the world, then we've got a contradiction. So the theist is left with this position: either the theist has to say
there is no evil in the world, or the theist has to give up one of these features of their God. Those are your two options. Neither of them look very appealing. And so now we're in a position to say, "If you don't want to do that, "you are an irrational theist," that there is compelling evidence
that God does not exist, God of this OOO kind does not exist, and yet, you believe anyway. That is to say, you
believe a contradiction. You believe that there is
evil, and there is no evil. You believe that there
is this kind of god, there isn't this kind of god. We saw before that belief in
contradictions is a bad thing, and you ought to avoid
it wherever you can. And so this is the argument
that you should not be a theist, because irrational theism is not an acceptable form of theism. Subtitles by the Amara.org community