A counterfactual changes a council's road plan but keeps a navigable river unchanged. What role does the river have in this comparison?

• A trigger that starts each transport decision.
• A pressure that must increase throughout the period.
• A backdrop that can still help transport.

Which procedure makes a counterfactual useful for testing a historical explanation?

• Change one plausible decision and trace its effects.
• Change several causes to get a preferred ending.
• Keep every later event fixed after changing its possible cause.

Knowing that a war occurred can make earlier peace proposals seem less likely to succeed than they seemed to people at the time.

A hypothetical account predicts that without a blockade, an army still loses because its supply road is cut. What does this suggest about the blockade's necessity for defeat in that account?

• The blockade had no effect on the campaign's timing, losses, or strategy.
• Defeat did not depend on the blockade in this account.
• The defeat proves that blockades cannot affect the outcome of any campaign.

In an invented town, a council adds a tax after a poor harvest. A counterfactual delays the tax but freezes later revenue at its original level without explanation. How should the setup change?

• Keep the earlier harvest fixed; investigate later revenue.
• Improve the earlier harvest too; then delay the tax.
• Keep later revenue and protests fixed; allow no consequences of the delay.

In an invented mill town, wage cuts build anger for months. A dismissal is followed by a strike the next day. Calling the dismissal a possible trigger does not show that it caused the strike on its own.

In an invented island case, a council delayed an available relief ship. Records link the delay to food shortages and shortages to protests; storms could also disrupt sailing. Keep earlier stores fixed and send it earlier. Which prediction about protests is best supported?

• Earlier sailing prevents storms, so supplies arrive and no protests occur.
• Earlier sailing cannot affect shortages or protests, since changing a decision leaves all later events fixed.
• Earlier sailing may ease shortages and reduce protests, but storms could still disrupt supplies.

Two invented districts suffer the same poor harvest. One council releases stored grain, and prices rise less there. What can this comparison support without more evidence?

• A policy difference is a possible cause to investigate.
• A shared harvest makes the districts identical in every other relevant respect.
• A different outcome proves the grain policy alone caused the smaller price rise.