I started this thread to avoid going off topic in another thread. I certainly pretend to no comprehensive treatment of this topic in this OP and invite a wide open discussion of monism, dualism, Edward Feser and hylemorphic dualism.
First of all substance dualism is the frame of reference. To quote the philosophy-index:
Substance Dualism is a variety of dualism in the philosophy of mind which states that two sorts of substances exist: the mental and the physical. Substance dualism is a fundamentally ontological position: it states that the mental and the physical are separate substances with independant existence.
To add a little more clarity somewhat derived from my preference for scientific thinking and terminology over philosophical and theological traditions, by “substance” I am talking about the stuff things are made of, what in Aristotle’s works is usually translated as matter (hule) when he looks at all things as different forms of a material substance. This resonates with the scientific worldview which views everything in the physical universe as different forms of energy.
Edward Feser, following the lead of Aquinas shifts this from the mind-body relationship to the body-spirit relationship, and this is the essence of hylemorphic dualism, that the “human soul” is the “substantial form of the human body” which survives after death. Frankly my view is effectively the same as this though technically and semantically different in various ways.
To begin with I am a substance monist and you know why? Because monism has more explanatory power than dualism. Monism provides an explanation for many dualities and pluralities. Ice, steam, water as three phases of one molecular substance. Heat, motion, mass, light, all different forms of one quantity called energy. All excellent explanations and so that is a methodology which I use for all things. Monism is superior to the dualistic approach because it adds an explanation of the duality itself.
Mind and body? Two interdependent living organisms in different self-organizing substrates but both a part of the same system of space-time mathematical laws. (Yes, with regards to the mind-body problem I am a physicalist – and yet the effective duality of mind and body is still there and quite strong, with not only different needs and desires but a completely different system of passing on an inheritance to the next generation). And because I am a Christian, I also believe in an effective duality of physical and spiritual largely based on 1 Cor 15, and yet I would suggest that they also are different forms of a single substance which might be called pre-energy or the pure potentiality of being itself.
So… I would say that hylemorphic dualism is mostly that which is presented by Paul in 1 Cor 15 though he does not use the world “soul” but the phrase “spiritual body.” Because of the non-Christian religious and philosophical origins of the word “soul” I shy away from that word, preferring the word spirit. And also there are ideas in Christian theologies typically associated with that word which I also reject, such as the soul being something created by God and inserted into people. This does not agree with Paul in 1 Cor 15, who says that the spiritual body is derived from and grows from the physical body, which is also my view. Then there is the typical idea that the soul is what distinguishes human beings from animals. By contrast my view of what distinguishes human beings from animals is the entirely physical/natural human mind while a spirit is something we have in common. To bring this in accordance with the findings of science that the only significant difference between man and the animals is our abstract capable language, I see language as the substance in which the human mind has its self-organization.