Post Author: Bill Pratt

In the previous post, we explained what substances, properties, and events are.  Now it is time to use those terms to explain what physicalists believe about human beings.  Philosopher J. P. Moreland explains below:

According to physicalism, a human being is merely a physical entity.  The only things that exist are physical substances, properties, and events.  When it comes to humans, the physical substance is the material body, especially the parts called the brain and central nervous system.  The physical substance called the brain has physical properties, such as a certain weight, volume, size, electrical activity, chemical composition, and so forth.

As far as human beings go, physicalists hold that they are physical substances with physical properties.  But what about events?  Are they also physical?

There are also physical events that occur in the brain.  For example, the brain contains a number of elongated cells that carry various impulses.  These cells are called neurons.  Various neurons make contact with other neurons through connections or points of contact called synapses.  C-fibers are certain types of neurons that innervate the skin (supply the skin with nerves) and carry pain impulses.  So when someone has an occasion of pain or an occurrence of a thought, physicalists hold that these are merely physical events – events where certain C-fibers are firing or certain electrical and chemical events are happening in the brain and central nervous system.

Are you getting the idea?  Everything about human beings can be reduced to physical substances, properties, and events.  You might be wondering how physicalists explain our thoughts, emotions, and pains.  Are these also physical?  Yes, they are.  According to Moreland,

My conscious mental life of thoughts, emotions, and pain are nothing but physical events in my brain and nervous system.  The neurophysiologist can, in principle, describe these events solely in terms of C-fibers, neurons, and the chemical and physical properties of the brain.

For the physicalist, a human being is 100% composed of matter, and nothing else.  There is a further crucial point that needs to be made about matter:  “No material thing presupposes or has reference to consciousness for it to exist or be characterized.”

Moreland elaborates:

You will search in vain through a physics or chemistry textbook to find consciousness included in any description of matter.  A completely physical description of the world would not include any terms that make reference to or characterize the existence and nature of consciousness.

So now you have a description of what physicalists believe about the mind and body.  They affirm that the body exists, but deny that anything like an immaterial mind exists.  For them, everything about human beings, and the world in its entirety, must be explained by physical/material substances, properties, and events. 

In our next post , we will look at what dualists believe.