I am not sure if publishers prefer people with a PhD degree. If someone is a good writer, no matter with or without a PhD degree, there is the chance to get the book published. It can happen that publishers want an outline of the book and a sample chapter. If the prototype convinces the publisher and if the publisher thinks the book will attract readers, it probably does not matter whether the author has a PhD or not. One of the most prominent examples in history is William Shakespeare, who, as far as it is documented, did not study at university. 

There is no degree requirement for writing a book!  However, you should have appropriate writing skills if an individual wants their publication to be successful!  Take some time in a bookstore and observe people browsing through books and watch their reactions.  This observation should give you an indication of the quality of  the material and if it appears to keep the attention of the browser.  Writing a book is the first step, however, finding a publisher is sometimes challenging.  Some companies will publish your work at a cost upfront from the author.  Thank you.

Dear Sukanta,

You ask if it is really necessary to have a PhD degree to write a book or books. Let me say that the concept of book is a broad concept. In can be a scientific book, a technical book, a novel, a book of poetry, and so forth.

With the exception of scientific and highly technical books, most of the books are not written by Ph D authors. As far as I know, the majority of, say, literary books were, are, and will certainly be written by individuals without a  PhD degree. Suffice it to say that many nobel laureates in the literary domain had no PhD degree. Albert Camus, Jean Paul Sartre, Jose Saramago are just three examples. The Portuguese writer Jose Saramago, for example, had even no college or university background.

As you say, there are several experienced personalites who do not have  a PhD degree but have got immense experience and that huge expertise is reflected in the form of book which became a significant contribution in their respective fields.

Of course, it is often the case that some publishers used to prefer the authors with PhD. However, this may not be always correct, as you righty say. I also guess that which you want to know is one's opinion about your question.

To sum up, my opinion about your question is that in general terms it is not necessary to have a PhD degree to write books. There may be some cases, for example, handbooks for undergraduate and graduate students the authors of which are PhD authors.

I am aware that I am saying what you already do know. I guess that those who are going to answer your question are going to say that the answer depends mainly of the type of book you are thinking about. If the idea is, for example, to write a handbook for college/university students, then to have a PhD may matter a lot. This is not the case for the majority of all other books. I think that a skilled professional, a economist, for example, can write a splendid book on economic issues.

So, may answer is a short answer and is not certainly a creative answer. I even wonder what a creative answer to your question would be.

Thanks for sharing your thoughts Mr. Orlando, Mr. Zhong, Mr. Downing and Mr. Spiegel. Yup, I should have clarified that it's about professional books not literature. In fact, to be specific I would like to Know about scientific observation and research related books. For example, domain of Earth sciences! 

Dear Sukanta,

of course, you are most welcome. Even if it is in a scientific subject area, I still think a PhD is not mandatory. I agree with Dr. Zhong, though, that prospective authors should know the subject very well.

Take care,

Rainer

Dear Sukanta,

From your message above, when you spoke in your initial question about to write a book, you did not clarify that you are to professional books, not literature. I continue to think, like it is expressed by several answers to your question, that it is not mandatory to have a PhD degree to write a professional book. Professionals without a PdD, who are knowledgeable about the subject matter at hand and have the adequate linguistic competence to convey what they want to (see Jimmy's answer) are in a good position to write informative books in their area of specialization.

What do you mean by Earth Sciences? Astronomy, environmental psychology? In these to cases, a PhD may help, but I can imagine excellent books on astronomy and environmental psychological written by authors without a PhD.

Best regards,

Orlando

Thanks for the informative answers.

Publishing a book is typically a commercial decision by the publisher, so the likelihood of high sales is the most important consideration.

A PhD is irrelevant for writing a book.