Copi and Four Rules of Logical Identity See : Irving Copi, Symbolic Logic (4th ed, 1973), page 138: 
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The reflexive identity rule is:

$\dfrac { \text p} {x=x}$ (reflexivity);

Does this mean that if I have $Fc$, I can then infer $c = c$ in my proof? 
I got $Fc$ after applying universal out to $(x)[Fx \text { & } Sx]$. What does the $\text p$ actual stand for?
Thank you!
 A: Typically this rule is stated as:
$$\frac{}{t=t}$$
... which makes it a lot more clear that you don't need anything in order to conclude or infer $t =t$ for any term $t$ .... because that is always true of course!
So maybe the $P$ expresses the idea that you can have infer $t=t$ from $anything$, it doesn't matter what.  Even as such, it still seems a little restrictive to say that I would need something at all (what if I have no premises to start out in the first place?) ... so I doubt that that is what they really meant anyway. So in the end I feel it is a rather poor way of expressing that you can infer $t=t$ at any point in the proof, without reference to any earlier statement.
A: The $\text p$ in the rule presumably stands for : $\text {premise}$
It means that in a derivation you can insert the formula $x=x$ after any line (after any premise).
The rule reflects (see page 137) the reflexivity of the identity relation : 

$(x)(x=x)$. 



Does this mean that if I have $Fc$, I can then infer $c = c$ in my proof ?

Yes : you can infer $c=c$ wherever you want in the proof, and thus also after $Fc$.
