Function recode from dplyr takes separate named arguments to describe replacements (see ... description). In your case it is sufficient to change the code into:
data$variable.r<-recode(data$variable, 'strongly disagree'=0, 'disagree'=1, 'agree'=2, 'strongly agree'=3)
Here 'strongly disagree' and others are argument names, 1 and others - argument values.