How do words express different strengths of claim?

A statement can express more or less commitment to an outcome. In selected future descriptions, may presents a possibility, is likely to presents the outcome as probable, and will presents it as an unqualified future assertion. These differences concern the claim being expressed, not a change in the underlying evidence.

The original fictional progress log says that a cart left the workshop and that arrival by noon has not been confirmed. The cart may arrive by noon leaves that arrival open as possible. The cart is likely to arrive by noon makes a stronger probability claim. The cart will arrive by noon states the outcome without an uncertainty word in that sentence.

Based on this progress log is an evidence qualifier: it identifies the stated basis for the claim. Including it makes the basis explicit, but does not show that the log is complete or that its information supports every strength of assertion. Removing it does not create new evidence either. The cart’s actual arrival remains a separate matter.

These words are not fixed numerical percentages. Context, other modifiers and the speaker’s purpose can affect their force; may can also express permission, and will has uses beyond this future-claim comparison. A stronger grammatical assertion is not a guarantee that an event will happen. The useful distinction is between expressed commitment, an identified evidence basis and what that evidence actually establishes.