[Tex/LaTex] No indent in the first paragraph in a section

indentationparagraphssectioningtypography

I am just curious that the following format looks good to you or not? The preamble I used is just 

\documentclass[12pt,a4paper]{article} 
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amssymb}

I don't feel it's so good because the first paragraph has no indent but the second does. If the first paragraph is much longer, than it's fine. But if not, it looks strange. Should I leave it, or you have suggestions for this?

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Best Answer

In addition to Werner's excellent answer I'd like to make some remarks.

The indent after a section title (section is used here in a very broad sense, that is, anything with a title) is a question both of personal taste and of typographic tradition.

Tschichold, for example, states that the first indent should be suppressed only after a centered title and that all other paragraphs must be indented (see notes). The Imprimerie Nationale, which the French consider as the supreme guide in typographical matters, states that the first indent must always appear. In British (and US) typography the first indent is usually suppressed. Other national typographic styles follow one or the other trend.

Some language modules for babel change LaTeX's default of suppressing the first indent: Albanian, Chinese, French, Galician, Serbian, and (Castilian) Spanish. Polyglossia extends the list: Albanian, Asturian, Basque, Breton, Catalan, Croatian, French, Galician, Greek, Interlingua, Italian, Occitan, Serbian, and (Castilian) Spanish.

The most important criterion to follow is being consistent across a document. Nobody (except perhaps in France) will hold against you a typescript where the "national tradition" isn't followed. However, breaking a well established tradition mustn't be taken lightheartedly, but also not too seriously.

The Spanish module for Babel allows for changing the style (the others don't). For Polyglossia here's what I do when I write a document in Italian:

\usepackage{polyglossia}
\setmainlanguage{italian}
\PolyglossiaSetup{italian}{indentfirst=false}

(yes, I like suppressing the first indent, also after noncentered titles).

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