The whole world can't go vegan at once
That's true, and nobody is proposing it. No large change in how people eat has ever happened overnight. Whether the whole world could switch at once has no bearing on whether the person asking can switch now.
Veganism is presented as a moral duty for everyone. But a duty that cannot be carried out by everyone is a strange kind of duty. The world's farms, supply chains, livelihoods and diets are built around animals, and many people have no realistic alternative. A sudden global switch would bring shortages, lost incomes and real hardship. Any honest case for veganism has to start from what is actually achievable, not from an ideal that ignores how food reaches most people.
Agreed, and it concedes nothing. An overnight global switch is not anyone's plan. Crops, supply chains, jobs and cooking habits all take time to shift. Every big change in diet, energy or transport has happened gradually, and this one would too.
The question veganism puts is not addressed to the world. It is addressed to the individual who can choose differently today. 'Ought implies can' is a fair principle. It means the duty falls on people who are able to act, and most people having this conversation are. The standard definition already allows for those who aren't: 'as far as is possible and practicable'. Someone with no access to alternatives is not being asked to do the impossible.
On capacity, the limit is speed, not size. Animals eat far more crops than they return as food. Most studies of a largely plant-based food system find it needs less farmland than the current one, not more. A gradual transition is therefore a matter of time and planning, not of running out of land or calories.
So the claim is correct about the timetable and silent on the ethics. The animal being bred and killed this week is not affected by how fast the rest of the world moves. That depends on the choice made by whoever buys it.
- Change has to be gradual: we can't end animal farming overnight
Different wording, same argument. The response above answers all of them.
Replacing someone's actual position with a weaker, distorted version, then refuting that instead. The original argument is left untouched.
How it applies here: When offered as a point against veganism, it rebuts a demand nobody makes: that the entire world switch at once. The actual position concerns what individuals who can change should do now, and the argument leaves that untouched.