- Paper is a kind of tool
- Inventing a tool allows / enables that tool to be used
- Hence, inventing paper allows paper to be used

- Inventing paper allows paper to be used
- If something is allowed to be used then the use of that something might increase
- So, inventing paper might increase the use of paper

- Using paper requires creating paper
- Creating paper requires cutting down trees
- Therefore, using paper requires cutting down trees

- Using paper requires cutting down trees
- If something requires something else then increasing that something requires an increase in that something else
- So, an increased use of paper requires an increase in the number of trees cut down

- Cutting down trees has a negative impact on an ecosystem / organisms living in an ecosystem
- If something has a negative impact on something else then increasing the amount of that something has a negative impact on that something else
- Therefore, increasing the number of trees cut down has a negative impact on the environment

- An increased use of paper requires an increase in the number of trees cut down
- Increasing the number of trees cut down has a negative impact on the environment
- Therefore, an increased use of paper has a negative effect on the environment by increasing the number of trees cut down

- Inventing paper might increase the use of paper
- An increased use of paper has a negative effect on the environment by increasing the number of trees cut down
- Hence, the invention and increased use of paper has a negative impact on the environment by increasing the number of trees cut down

- The invention and increased use of paper has a negative impact on the environment by increasing the number of trees cut down
- An impact means an effect
- Therefore, a negative effect of the invention and use of paper is an increased number of trees cut down

So, a negative effect of the invention and use of paper is an increased number of trees cut down
Q: A negative effect of the invention and use of paper is the
Context:
- Cutting down trees has a negative impact on an ecosystem / organisms living in an ecosystem 
- Using paper requires creating paper 
- Creating paper requires cutting down trees 
- If something has a negative impact on something else then increasing the amount of that something has a negative impact on that something else 
- If something is allowed to be used then the use of that something might increase 
- Paper is a kind of tool 
- Inventing a tool allows / enables that tool to be used 
- If something requires something else then increasing that something requires an increase in that something else 
- An impact means an effect