I want to write a script in filemaker which returns true if table::field = 1
for a certain entry, and false otherwise. How do I do this?
A script can return a value with the Exit Script step. To return a Boolean value set the step's result to your expression: Table::Field = 1. The Table::Field must be accessible in the current context (i.e. layout). The result will be the Boolean you're looking for (technically it will be a number). To access this value you need to query it with the Get( ScriptResult ) function.
The way you describe it it doesn't really sound FileMaker, so if this is not the answer you expected, please provide some context for what you're trying to accomplish.