Does an erection of the male organ during the daytime in Ramadan, whether pleasurable or not, invalidate the fast, and what is its ruling?

The mere erection of the penis during a Ramadan day does not invalidate the fast, whether it is with pleasure or without pleasure, even if it results from foreplay or if madhy (pre-seminal fluid) is discharged from it. The relied-upon opinion is that the criterion for arousal of desire is the fear of ejaculation.