The debate between indoor-only and outdoor cat management involves genuine welfare tradeoffs between behavioral expression and safety from cars, predators, disease, and the significant welfare impact on wildlife.
The indoor-outdoor debate is genuinely complex from a welfare perspective. Cats evolved as outdoor hunters — restriction to indoor environments can cause frustration of hunting motivation, obesity from reduced exercise, and stress in multi-cat households with insufficient space. These are real welfare costs. The welfare costs of outdoor access are also real: shorter lifespan through accidents and disease, injury from territorial conflict, and the welfare harm inflicted on the wildlife cats kill. The welfare-optimal approach provides enriched indoor environments that address behavioral needs combined with supervised or enclosed outdoor access that provides stimulation without predation opportunity. This middle path is more labor-intensive than either pure indoor or pure outdoor management but addresses both sets of welfare concerns.