How do you know something is dead

No vital signs

Vital signs include heart rate, respiratory rate, temperature and blood pressure

Is this without equipment?

Depending on what organism you are talking about, animals that can be seen with the unaided eye you can tell that they are dead by studying their bodily movements such as the rise or falling of their chest.

Plants with the unaided eye, the best  indicator is to take a branch or piece off and study the insides color, if it is green then mostly likely they are alive.

Now microscopic organisms are harder to say, it depends on what you are referring to.

google my dude. if it doesn't show up ask me.

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.