ものと思う・
ものと思う presents a belief or expectation in a measured style common in writing and careful formal speech. ものと思っていた looks back on an earlier assumption, often before a correction or unexpected result.
Meaning and time
The clause before もの gives the content of the belief. With 思う, the writer or speaker presents that belief as a current conclusion or expectation. Changing the final verb to 思っていた moves the belief into the past.
Current expectation and earlier assumption
Notice that the first sentence states a present assessment, while the second explicitly shows how an earlier expectation was later corrected.
本委員会は、提出された資料が信頼できるものと思う。
The committee believes that the submitted materials are reliable.
Analyze当初、担当者は設備の更新だけで問題は解決するものと思っていたが、実際には運用方法の見直しも必要だった。
Initially, the person in charge had assumed that updating the equipment alone would solve the problem, but in fact the operating procedures also needed review.
AnalyzeStrength and point of view
This construction sounds considered and deliberate, but it does not necessarily express absolute certainty. The thinker may be the writer, speaker, committee, organization, or another person, and should be clear from the sentence or surrounding context.
Choosing among similar forms
と思う is the ordinary choice for an everyday thought or opinion, whereas ものと思う gives the belief a more measured written tone. に違いない states stronger conviction more directly. ものとする does something different: it adopts an assumption or treatment for a rule, analysis, or procedure rather than reporting someone's belief.
私は、明日の会議は短いと思う。
I think tomorrow's meeting will be short.
AnalyzeThis neighboring form is the natural unmarked choice for a simple personal opinion.
More examples
専門家の多くは、新制度の効果が年内に現れるものと思っている。
Many experts believe that the effects of the new system will become apparent by the end of the year.
Analyze事務局は、すべての審査を今月中に終えるのは難しいものと思う。
The secretariat believes that it will be difficult to complete all the reviews this month.
Analyze調査班は、その時点では、二つの事例に関連はないものと思っていた。
At that point, the investigation team believed that the two cases were unrelated.
AnalyzeNo later outcome is stated here; the surrounding context must show whether the team's belief eventually changed.
会長は式典が予定どおり始まるものと思っていたが、停電のため開始が遅れた。
The chair had expected the ceremony to begin as scheduled, but a power outage delayed the start.
Analyze委員会は、事故の主な原因が部品の劣化であるものと思う。
The committee believes that the main cause of the accident was deterioration of the component.
Analyze私は、追加の検証によって結論の信頼性はさらに高まるものと思います。
I believe that further verification will make the conclusion even more reliable.
Analyze