Thesis writing style: when to italicize?

Question

In a thesis or journal you write all sentences yourself, but on some occasions you prefer to take a piece of text from another source. If you do, should you use quotation marks only, or italicize it, or use both, to identify that you have not written it?

Example for quoting directly from a source:

1. This can, according to Someone et al. [1], be seen as "an excellent way of representing a piece of text quoted from another source", and therefore it's emphasized.
2. This can, according to Someone et al. [1], be seen as "an excellent way of representing a piece of text quoted from another source", and therefore it's emphasized.
3. This can, according to Someone et al. [1], be seen as an excellent way of representing a piece of text quoted from another source, and therefore it's emphasized.

Example for a definition with a source:

1. Wikipedia defines italic as "a semi-cursive, slightly sloped style of handwriting and calligraphy that was developed during the Renaissance in Italy" [2].
2. Wikipedia defines italic as "a semi-cursive, slightly sloped style of handwriting and calligraphy that was developed during the Renaissance in Italy" [2].
3. Wikipedia defines italic as a semi-cursive, slightly sloped style of handwriting and calligraphy that was developed during the Renaissance in Italy [2].

Are there are any style guides or recommendations that refer to italicized text, for either quotes or definitions? And related to the two examples, what is the recommended way to distinguish between a quote and a definition?

Edit: note that if a style guide is provided, the guide should be followed. This question relates to situations where no style guide is required.

Answer 1

There can be specific exceptions for journals, which may have conventions preserved unchanged from the past, but the general principle is to be typographically simple while conveying the necessary information. Quotation marks are required to unambiguously indicate that a certain sequence of text is a literal quotation; the quote itself should then not modify the format of the text, thus should be roman when the original is roman, italic when it is italic, and so on. Thus, your first option would be the correct choice.

Answer 2

While quoting verbatim from a source, you should always use quotation marks. Italics are generally used for the following purposes:

• titles of books, periodicals, blogs
• genera, species, and varietes
• introduction of a new technical term
• letters used as statistical symbols or algebraic variables
• some test scores and scales
• periodical volume numbers in reference lists

If you have used quotation marks to indicate that you have borrowed the text, I do not see any need to italicize it. Style guides also advise against the use of italics for mere emphasis. Hence, it is better to use quotation marks only to distinguish text that you are using verbatim from another work.

Answer 3

I agree with User6726’s answer, but want to add a few things.

For a journal publication (to make the answer more general) you could check the journal’s style guide or how italic type is used within articles published in the journal.

As your question is specifically about a thesis, find out which style your thesis should be in (APA, Chicago, etc.). You will be needing this information for formatting your references anyway. With this information, check online or in your library for a a style manual for the specific style. This manual will explain when italics are appropriate.

Answer 4

Italics are used for emphasis. Use sparingly, where required by custom (biologists write species in italics, I believe), to highlight a new term being introduced, and precious little else.