
Shitty Ask Science
Let's try a proof by contradiction: begin by assuming that potatoes have the ability to think, then derive a contradiction using logical inferences.
If a potato had the ability to think it would find my personality respulsive, as any thinking creature does.
If a potato found me repulsive, they would do everything in their power to locomote away from me, or at the least not attempt to take root.
Based on the potatoes that I purchased at the supermarket last week and forgot about, I can say that potatoes will attempt to take root in my presence, a fact incompatible with sentience. We've arrived at a contradiction, therefore potatoes lack sentience.
Try to create a potato-powered AI. It will be as smart as the average human being.
If only we could cozzen the oligarchs into thinking that potatoes are a better source of power for the A.I. data centers, we could avoid a 'Matrix' style dystopia.

First you have to define what "think" is.
Is it being self-aware? Is it responding to stimuli? Is it having brainwaves, or just a brain?
Then you have to ask if thought is something we would always recognize. Could something think in a way that is totally recognizable to us but is still thought? Do computers think? Why or why not?
First you have to define what “think” is.
That’s your answer right there—just define thinking as whatever a potato doesn’t.
Just start talking.
You're mom won't have sex with them.
Anything can be a dildo if you're brave enough.
EEG?