The term metaphysics is derived from the Greek phrase Ta Meta ta Physkia which simply means "the books after the books on nature." When a librarian was cataloging Aristotle's works, he did not have a title for the material which he wanted to shelve after the material called "nature" (Physkia) - so he simply called it "after nature." Originally, this wasn't even a subject at all - it was just a collection of notes on different topics, but specifically topics which were removed from normal sense perception and empirical observation.

It has been said that metaphysics is the finding of bad reasons for what we believe on instinct.
- W. Somerset Maugham (1874-1965), The Summing Up (1938).

In Western philosophy, metaphysics has become the study of the fundamental nature of all reality - what is it, why is it, and how are we to understand it. It has also become the label for the study of those things which transcend the natural world - that is, those things which supposedly exist separately from nature and which have a more intrinsic reality than our natural existence. As a result, the popular sense of metaphysics has been the study of any question which cannot be answered by scientific observation and experimentation.

The study of metaphysics is then, in a general sense, an attempt to study very substance of reality - to understand why things exist at all and what it means to even exist in the first place. A significant portion of metaphysics is taken up by theology, the study of gods: does a god exist, what a god is, what a god wants, etc.

Some, like logical positivists, have argued that the agenda of metaphysics is largely pointless and can't accomplish anything. According to them, metaphysical statements cannot be either true or false - as a result, they don't really carry any meaning and shouldn't be given any serious consideration.

I don't know if William Somerset Maugham subscribed to logical positivism, but his comment here seems to be in line with what many logical positivists argued. If it is indeed the case that metaphysics produces only "meaningless" statements, then it should also be true that none of the "reasons" it gives for this or that belief can be valid. Why, then, would people continue to pursue it as if it were a valid field of research?

One possible reason is that it is so malleable, so responsive to our prejudices and desires, that it is relatively easy within metaphysics to come up with "answers" that agree with what we already believe and "reasons" for our beliefs that only serve to reinforce what we wish to be true. It cannot be denied that similar things occur in other fields of study, so metaphysics would not be unique on that point, but if the claims of metaphysics are "meaningless" whereas those made in other fields are not, then metaphysics may be far more susceptible to this problem.

People have a strong tendency to seek out information that supports what they already believe and to ignore information that might tend to undermine their beliefs. This is called "confirmation bias" and is a well-known facet of thinking that contributes greatly to people's resolute adherence to bad beliefs. Whether the context is metaphysics, politics, religion, or even science, it's something that we all need to be on the watch for because it can easily prevent us from properly evaluating what we believe and seriously considering alternatives.