How to disable indentation of LaTeX list items? [closed]

Answer 1

I compiled the three suggested methods into one file to be able to compare them side by side. Note that \setlength{\leftmargin}{0pt} does not have any effect on the "enumerate" environment. So far, the best solution is the "list" environment using the option "\leftmargin=1.4em". However, I do not like a constant number in my code for it makes the code fragile. Does anyone know how to compute this constant (1.4em) in terms of available LaTeX variables?

\documentclass{article}
\begin{document}

\section*{Paragraph}
\paragraph{1.} First
\paragraph{2.} Second
\paragraph{3.} Third

\section*{list}

\newcounter{itemcounter}
\begin{list}
{\textbf{\arabic{itemcounter}.}}
{\usecounter{itemcounter}\leftmargin=1.4em}
\item First
\item Second
\item Third
\end{list}

\section*{enumerate with leftmargin}
\begin{enumerate}
\renewcommand{\labelenumi}{\textbf{\theenumi}.}
\setlength{\leftmargin}{0pt}
\item First
\item Second
\item Third
\end{enumerate}

\end{document}