\documentclass[a4paper,12pt,twoside]{book}
\usepackage{etex}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath,amssymb,amscd,amsbsy,array,color,epsfig}
\usepackage{fancyhdr,framed,latexsym,multicol,pstricks,slashed,xcolor}
\usepackage{picture}
\usepackage{indentfirst}
\usepackage{enumitem}
\begin{document}
\begin{proof}
\begin{table}[!ht]
\centering
\begin{tabular}{|c|c||c|c|c||c|c|}
\hline
$P$ & $Q$ & $P \Rightarrow Q$ & $\neg P$ & $\neg Q$ & $(\neg Q) \Rightarrow (\neg P)$ & $Q \Rightarrow P$ \\
\hline
$T$ & $T$ & $T$ & $F$ & $F$ & $T$ & $T$ \\
\hline
$T$ & $F$ & $F$ & $F$ & $T$ & $F$ & $T$ \\
\hline
$F$ & $T$ & $T$ & $T$ & $F$& $T$ & $F$ \\
\hline
$F$ & $F$ & $T$ & $T$ & $T$ & $T$ & $T$ \\
\hline
\end{tabular}
\caption{\emph{Truth Table for $P \Rightarrow Q$, $(\neg Q) \Rightarrow (\neg P),$ and $Q \Rightarrow P.$}}
\end{table}
\end{proof}
\end{document}
Hopefully I have given enough information in the MWE, because in my original I have a preamble, a table of contents, a chapter 0 (from which the table comes), and an analysis file which has the previous as inputs. So, I might have left something out that is needed from the MWE for it to compile.
But when I compile I get the following error at the beginning of the table:
Not in outer par mode \begin{table}[!ht]
Undefined control sequence \begin{table}[!ht]
Missing number, treated as zero \begin{table}[!ht]
Thanks.
\usepackage{amsthm}
is missing ifproof
is used (or alternatively\usepackage{mathtools}
. I don't think that your really need theetex
package nowadays any longer. Also don't use the outdatedepsfig
packageetex
andepsfig
packages shouldn't be used in current documents (not since 1994 in the case ofepsfig
)