# Inviscid aerodynamics: why is circulation zero at the wingtip?

I read that the circulation at the wingtip for a finite wing is $0$. I am a little bit confused about this statement. First, it is said that drag due to lift (aka induced drag) generates vortices at the wingtip. But on the other hand in Prandtl's lifting line theory the circulation at the wingtip dies off. I thought about some explanations but I would like to know which one is really true. I also welcome any additional explanations.

1. Pressure difference at wingtip is $0 \implies$ no lift $\implies \Gamma = 0$.
2. Indirect: If the circulation at the wingtip is not equal to $0$, then the downwash due to wingtip vortex is infinitely large, which is not possible. This gives $\Gamma =0$ by contradiction.

$$\Gamma(\Theta)=4sV_{\infty} \sum_{n=1}^{\infty}A_nsin(n\Theta)$$