“Materialism is the view that everything is ultimately material in nature. At the most fundamental level, everything that exists consists of nothing but matter and energy. Everything is governed by the basic laws of physics and, in principle, can be completely explained in terms of those physical laws. Every object is a purely physical object. Every event that occurs has a purely physical cause (if it has any cause at all. In short, the universe is just a collection of clumps of matter following the laws of physics.
Materialists reject the idea that there are immaterial or spiritual entities, such as souls, angels or God. For that reason, they deny that there is life after death. (“After you die, you rot,” as more than one Materialist has said.) Materialism is the most widespread Atheist worldview in our day, mainly because of the extent to which modern science has come to dominate our view of the universe and ourselves. Science has been able to explain so much about the world that some people expect it will eventually explain everything. But science ultimately explains things in terms of matter and physical laws, so if science can explain everything, it follows that everything must be material in nature governed by the laws of physics.
Many people find Materialism attractive because it places great emphasis on such scientific explanations. Its view of the basic constituents of the universe is relatively clear and uncluttered: only matter and energy exist. Nevetheless, its advocates often don’t recognize that it faces a number of formidable difficulties and challenges that make it hard to defend rationally.
For example, Materialism has great difficulty accounting for our mental lives and our conscious experience of the world. If you’re a consistent Materialist, you ought to conclude either that you are literally mindless (which isn’t a very appealing conclusion) or that minds and consciousness can be explained in entirely material terms (which no Materialist has been able to do). Minds, ideas, thoughts and sensations are so very different from physical things that it’s hard to see how they could be explained in purely physical terms. Physical things have physical features, such as size, shape, speed, and mass- but minds and ideas don’t have those features. (What size is your mind? How much does it weight?)
In contrast, ideas in our minds can be meaningful and true. But it makes no sense to ask what clumps of matter “mean” or whether they are “true” -unless those clumps of matter have been arranged in a meaningful way by a mind (for example, pebbles on a beach arranged to spell out “I love you”).
There is a further difficulty for Materialism. Recall your earlier answer to the Goodness Question: you agreed that some things really are objectively good or bad. However, many philosophers have raised this question: If Materialism is true, what basis is there for claiming that anything in the universe is objectively good or bad, right or wrong? In a godless, mindless, purposeless material universe, on what basis could one clump of matter be ultimately considered any better or worse than any other clump of matter?
Clumps of matter as such aren’t good or bad, right or wrong. They are just what they are and do what they do, following the laws of physics. So if human beings are ultimately just clumps of matter alongside all other clumps of matter, what basis is there for making meaningful moral judgments about how human beings behave? In a Materialist worldview, the only real laws are the laws of physics. But the laws of physics only tell us how clumps of matter do behave. They tell us nothing at all about how clumps of matter ought to behave, in any meaningful moral sense.”
(Anderson, What’s in a Worldview? 69-70)