Many aspects of doctoral supervision are well known from methods and methodology to research questions, philosophies and epistemologies. A core aspect that is touched upon less frequently yet is central to the lived experience of the researcher (and that is essential for rigour and trust occupying a significant amount of cognitive effort) is confidence and doubt. The use of confidence and doubt to drive research is a daily experience for the researcher yet the practice and challenges are infrequently addressed directly in doctoral environments. Confidence can be essential as a driver when researchers with strong convictions lack complete arguments to justify actions based on experiential, innate or purely intuitive motivations. Doubt can act as a valuable aid to personal critique and can mitigate the excesses of over-confidence. Overconfidence can blind a researcher to critical flaws whereas excessive doubt can destroy promising findings and innovations before they are proven. The authors explore how the initial worries and concerns from novice researchers about reliability and rigour transform into an exchange between confidence and doubt which become central generators balancing critique, risk, experimentation, and honesty. We review a wide range of diverse theories and concepts exploring different perspectives with a view to supporting those building research careers with positions from which to gather insight to strengthen their practices. Particular value can be gained from the decision-making routes that can follow from a better understanding of what underpins the drive for certainty.