They agree that cause and effect has not yet been definitively proved.

This means that there is no way a truth can be definitively proved to others.

But a tissue type can't prove definitively that two people are related.

The link between long hours and medical mistakes isn't definitively proved.

Ultimately there is no evidence to definitively prove either hypothesis.

However, those conclusions have yet to be definitively proven in humans without more research.

So, they say, it will be difficult to prove definitively that the crystals are a sign of life.

But what has been proved definitively is that skills learned in school slip significantly during the summer break.

Only recently was it definitively proved to be an accurate theoretical analysis.

In 2012 Australian scientists definitively proved the island does not exist.