The vertical skip from baseline to baseline within regular text is given by \baselineskip
. Within tabular
, this is 0pt
but it is still accessible as \normalbaselineskip
. Using your example as reference, it is clear to see that the vertical baseline skip still holds when drawing a vertical 1pt
rule of height \normalbaselineskip
:

\documentclass{article}
\begin{document}
\begin{tabular}{*{5}{|c}|}
\hline
$p$ & $q$ & $p \land q$ & $p \lor q$ & $p \to q$\\
\hline
T & T & T\smash{\rule{1pt}{\normalbaselineskip}} & T & T\\
\hline
T & F & F & T & F\\
\hline
F & T & $f$ & T & T\\
\hline
F & F & F & F & T\\
\hline
\end{tabular}
\end{document}
If you have a very particular table, like the one in your example, where baseline alignment may seem to be inadequate, you could play around with the addition of a vertical "strut" like in the following example:

\documentclass{article}
\usepackage{array}% http://ctan.org/pkg/array
\begin{document}
\newlength{\mylen}\settowidth{\mylen}{$p \to q$}% Widest element
\begin{tabular}{*{5}{|>{\centering\arraybackslash\rule{0pt}{1.05em}}m{\mylen}}|}
\hline
$p$ & $q$ & $p \land q$ & $p \lor q$ & $p \to q$\\
\hline
T & T & T & T & T\\
\hline
T & F & F & T & F\\
\hline
F & T & F & T & T\\
\hline
F & F & F & F & T\\
\hline
\end{tabular}
\end{document}
Using the array
package, it allows you to insert <stuff>
before every table column entry using >{<stuff>}
. Using the m{<width>}
column specification, I've fixed the column widths (I think it looks cleaner that way) and reverted back to the centering supplied by c
-columns.
Although this may be a moot point based on personal preference, consider using the booktabs
package to typeset tables:

\documentclass{article}
\usepackage{array}% http://ctan.org/pkg/array
\usepackage{booktabs}% http://ctan.org/pkg/booktabs
\begin{document}
\newlength{\mylen}\settowidth{\mylen}{$p \to q$}% Widest element
\begin{tabular}{*{5}{>{\centering\arraybackslash}m{\mylen}}}
\toprule
$p$ & $q$ & $p \land q$ & $p \lor q$ & $p \to q$ \\
\midrule
T & T & T & T & T \\
T & F & F & T & F \\
F & T & F & T & T \\
F & F & F & F & T \\
\bottomrule
\end{tabular}
\end{document}
\hline
commands are the cause of the misconception about the alignment. I'm posting a non-solution further on that shows the rows are aligned to the base line. Please note that I've removed the vertical lines in thetabular
environment because thebooktabs
package doesn't like them. Personally, I'd remove all the\midrule
commands as well, except for the first.array
package and all comments in this tex.stackexchange.com/questions/40581/… Thread, i think they might help you.mycell