Step 1: Understanding the Question:
The reporter interviewed only some of the parliamentarians, a sample, and each one said they voted by conscience. From this sample the argument concludes that probably all parliamentarians voted by conscience. We need to name this reasoning pattern.
Step 2: Key Approach:
When a conclusion about an entire group is drawn from a smaller, observed sample of that group, and the conclusion is stated with a hedge like "probably" rather than as a certainty, that is the mark of inductive generalization. A deduction, by contrast, would need a premise that already covers every member of the group, and it would not need the word "probably" since a valid deduction guarantees its conclusion.
Step 3: Detailed Explanation:
The premise here only covers the parliamentarians the reporter actually interviewed, not the whole set of parliamentarians. Yet the conclusion reaches out to "all the parliamentarians", a wider group than was actually observed. This step, sample to whole population, plus the qualifying word "probably", is the textbook shape of an inductive generalization.
It is not a predictive argument because nothing about a future event is being forecast, the claim is about how people already voted. It is not generalization based on authority because the parliamentarians are the subjects being generalised about, not experts whose word is cited as proof. It is not deduction because a genuine deduction would need a premise about every parliamentarian and would not need to hedge with "probably", since deductive conclusions follow with certainty from their premises.
Step 4: Final Answer:
Moving from an interviewed sample to a probable claim about the whole group is inductive generalization.
\[ \boxed{\text{Inductive generalization}} \]