You're not searching for truth, you're searching for confirmation.
Confirmation bias means you notice, remember and actively seek information that fits what you already believe. Peter Wason showed it in 1960 with the number sequence 2-4-6: almost every participant only tested examples that confirmed their own rule, which is exactly why they never found the real one.
Useful: For every firm opinion, ask: what evidence would change my mind?
Source: en.wikipedia.org