> Can you tell me how psychology exists without the mind?
It doesn't (well, except maybe behavioral psychology, which arguably could) exist without the mind.
It just doesn't care one way or another about whether the mind is a direct product of the physical body or not. “Mind/body” duality isn't just “the mind exist”, but “the mind is at least in part not a property of the body”.
> If psychology isn't predicated on mind/brain duality, what is it predicated on?
Depends what particular branch. Behavioral psychology is predicated on humans existing and having behavior, most of the rest of psychology is predicated on humans existing and having cognition, whether or not that cognition is a property of the physical body.
> Okay. So psychology requires the mind. Good. Does psychology deny the brain exists? If not, you have the mind-brain duality.
No, mind-brain duality isn't “mind and brain both exist” but “mind exists independently of brain”. (It's usually referred to as mind/body duality rather than mind/brain duality now because no one actually thinks the physical basis of the mind is purely brain, and the essence of the purported duality isn't the mind having a physical locus other than the brain but it having some not-physically-determined aspect.)
Does neuroscience rely on neuron/collection-of-atoms duality?
IIUC, classically "mind-body dualism" involves an assertion that the mind cannot be explained physiologically. Psychology only asserts that the mind can be reasoned about directly. The usefulness of psychology depends on that reasoning being sufficiently accurate and sufficiently easier than reasoning neurologically for some problems.
> Does neuroscience rely on neuron/collection-of-atoms duality?
No because such duality doesn't exist. It's a relationship of composition rather than duality. It's empirically shown that neurons and atoms exist and neurons are composed of atoms. Last I checked, there isn't any empirical evidence for "the mind" just like there isn't any empirical evidence for "the soul". And nobody is asserting that the mind is composed of brains.
> IIUC, classically "mind-body dualism" involves an assertion that the mind cannot be explained physiologically.
No. Classically, the mind-body dualism is the idea that the mind and body are distinct separate entities and that the mind does the "thinking" and the body cannot "think". Has nothing to do one explaining the other.
> Psychology only asserts that the mind can be reasoned about directly.
Not directly, indirectly.
> The usefulness of psychology depends on that reasoning being sufficiently accurate and sufficiently easier than reasoning neurologically for some problems.
Or... there is no such thing as a mind-body duality and it's all just body and psychology is pseudoscience. Mind-body dualism is just a rehash of the soul-body dualism. People used to believe that the soul controlled the body and that's why the body could move. People used to believe that the sickenness of the soul translated to sickenness of the body. Hence why people used to believe diseased people were cursed by god for their sins. We don't subscribe to that belief anymore after advances in physiology. As we learned more about the body, the soul slowly faded away. Makes one wonder what advances in neuroscience may do to the mind.
It doesn't (well, except maybe behavioral psychology, which arguably could) exist without the mind.
It just doesn't care one way or another about whether the mind is a direct product of the physical body or not. “Mind/body” duality isn't just “the mind exist”, but “the mind is at least in part not a property of the body”.
> If psychology isn't predicated on mind/brain duality, what is it predicated on?
Depends what particular branch. Behavioral psychology is predicated on humans existing and having behavior, most of the rest of psychology is predicated on humans existing and having cognition, whether or not that cognition is a property of the physical body.