These words refer to an act, decision or situation that is subject or subordinate to factors either in evidence or thought likely to come about. Provisional may refer merely to something adopted for the moment out of temporary necessity or until something adopted better can be arranged: a provisional plan. More pertinent here, the word often suggests a situation that is allowed to exist provided certain results are forthcoming: given provisional status as a matriculated student until his examination results were available. The word usually suggests that the crucial factors determining ultimate status are those that lie in the future. Something even less certain than provisional is tentative , which means experimental in nature. Provisional actions, methods, etc., would have greater chances of adoption or success than those that are tentative : He made a few tentative moves to find a solution to the problem before giving in altogether.

Dependent , by contrast with provisional , may indicate something subject to factors past, present or future: rapid growth that was dependent upon the groundwork laid in the last century; a sense of well-being that is dependent mainly on overall physical health. The word also often suggests factors that may be imposed or stipulated as part of an agreement or contract: an increased allowance that was to be dependent upon the uses to which it was put.

Conditional stresses almost exclusively this last sense of dependent, suggesting an agreement that will be honoured by one side if its terms are held to by the other: conditional approval of the book, provided certain passages were deleted. The word, less specifically, may simply mean tentative : could give only conditional (or tentative ) praise to the report, not having studied the transcript in detail. Contingent may refer at its least complex to something liable to happen: fearing that defeat was contingent . It may also indicate something unforeseen or occurring by chance or accident: contingent catastrophes. A more pertinent and wider use is to suggest a cause-and-effect relationship of any sort: a political victory wholly contingent upon the personal popularity of the winner. The word may also suggest something dependent upon an uncertain event or condition.

• Historical processes are contingent upon so many imponderables as to make untenable the approach of the scientific determinist.