Deductive Forms Identification

Modus Ponens and Modus Tollens, Part 1

Valid in Deductive Terms Ponens Modus

P As a result, Q (Conditional statement) P (Hypothesis) Q (Conclusion)

Question 1: If you have an effective rehabilitation program, recidivism rates will be lower. (Conditional assertion)

Because you have successful rehabilitation programs (hypotheses), recidivism rates have decreased. (Conclusion) With this declaration, you affirm that successful rehabilitation is adequate to reduce your recidivism rate.

Question 2: If Bennie's offender risk assessment is favorable, he may be granted conditional release on his statement.

He has a low offender risk assessment.

As a result, he may be granted conditional release on his statement. In this argument one hypothesis can be false, but the argument is still valid, this statement does not tell us whether the Bennie has a favorable offender risk assessment or not, but all in all the statement is valid ("Modus Ponens, Modus Tollens," 2017).

Question 3

If the public wants safer streets then the public will ask the city to spend more tax dollars on policing. (Conditional statement)

The public wants safer street (Hypotheses)

Therefore

The public will ask the city to spend more tax dollars on policing (Conclusion)

In this argument affirms that for a more secure street the public will ask the city to spend more tax dollars on policing, hypothesis can be false, we do not know if the streets are safe or not but the statement is valid.

Deductively Valid Modus Tollens

If P then Q

Not Q

Therefore not P

If rehabilitation programs are successful, then there is a reduction in recidivism rates

There is no reduction in recidivism rates

Therefore

Rehabilitation programs are not successful

In this premise argues that due to rehabilitations programs not being successful, they will not receive reduction in recidivism rate.

If Bennie has a favorable Offender Risk Assessment, then Bennie can receive a conditional release on his sentence

Bennie cannot receive a conditional release on his sentence

Therefore

Bennie does not have a favorable offender risk assessment

In this statement due to Bennie not having favorable offender risk assessment, Bennie will not receive a conditional release on his sentence.

If the public wants safer streets, then the public will ask the city to spend more tax dollars on policing.

The public will not ask the city to spend more tax dollars on policing

Therefore

The public does not want safer streets

In this statement denies, if the public does not want safer streets then they will not ask the city to spend more tax dollars on policing to be able.

Part 2: Arguments with Missing Parts

Question 1

If Meg is a highly motivated RCMP Cadet, then she is sure to graduate from the cadet training program (Condition statement)

Meg is a highly motivated RCMP Cadet (Hypotheses)

Therefore

She is sure to graduate from the cadet training program (Conclusion)

In this theory affirm that Meg is a highly motivated RCMP Cadet. Therefore she is sure to graduate from cadet training program.

Question 2

If the defendant enters a plea of guilty or not, then we know for a fact that the defendant will not enter a guilty plea. (Conditional statement)

The defendant will enter a plea of guilty or not guilty (hypotheses)

Therefore

We know for sure the defendant will not enter a guilty plea. (Conclusion)

In this argument affirm that the defendant will enter a plea of guilty or not, we are sure he will not enter a guilty plea.

Question 3

If foot patrols are increased then, residents will feel less afraid of crime, if foot patrols are increased then the police-citizens relationship will be improved (conditional statement)

Foot patrols are increased (hypotheses)

Therefore

Residents will feel less afraid of crime, or the police citizens’ relationship will be improved (conclusion)

In this argument affirms that if foot patrols are increased then residents will feel less afraid of crime or police-citizen relationship will be improved, the hypotheses can be false, we are not sure if increased in foot patrols things will change, but the argument is valid.

Question 4

If we reduce foot patrols, then people will be less mindful of the law. If people are less mindful of the law, then people will be tempted to do more crimes of opportunity such as purse snatchings and smash-and-grabs. If we are reducing foot patrols, then the conclusion is obvious. (Conditional statements)

If we reduce foot patrols and people are less mindful of the law (hypotheses)

Therefore

people will be tempted to do more crimes of opportunity such as purse snatchings and smash-and-grabs, and the conclusion is obvious

In this argument, it affirms that if we reduce foot patrols and people less mindful of law, then people will be tempted to do more crimes of opportunity such as purse snatchings and smash-and-grabs and the conclusion is obvious.

Part 3: Invalid Arguments

Question 1

If the defendant did the crime, then he would have got the victim's blood on his clothes. If Evidence clearly shows that the defendant did get the victim's blood all over his clothes, then we can conclude that the defendant did the crime.

He would not have got the victim's blood on his clothes, and we cannot conclude that the defendant did the crime

Therefore

The defendant did not commit the crime and Evidence clearly did not show that the defendant did get the victim's blood all over his clothes

In this statement denies defendant committing any crime, for evidence clearly did not show that the defendant did get the victim's blood all over his clothes.

Question 2

If the defendant had the victim's blood on his clothes, then there is no doubt the defendant attempted to murder the victim. If the defendant did not have any of the victim's blood on his clothes, then the defendant did not attempt to murder the victim.

There is no doubt the defendant did not attempt to murder the victim

Therefore

The defendant did not have any of the victim's blood on his clothes

In this statement, there is no doubt the defendant did not attempt to murder the victim, and for that reason, defendant did not have any of the victim's blood on his clothes.

Question 3

If all offenders on probation are offenders who are not a danger to society, Meg is an offender who is not a danger to society. Then we can conclude that Meg is an offender on probation.

We can conclude that Meg is not an offender on probation

Therefore

All offenders on probation are offenders who are a danger to society. Meg is an offender who is a danger to society

In this argument all offenders on probation are offenders who are a danger to society; Meg is an offender who is a danger to society. Therefore, we can conclude that Meg is not an offender on probation.

Part 4: Essay Analysis Value

Some people said that police are ineffective. They said that either the police are there to make the community safe or the police are just sitting around collecting a paycheck. Since the community is not totally safe, (P), then it is clear that the police are just sitting around doing nothing but collecting a pay check. (Q)

Some people said that police are ineffective (C)

If the police are there to make the community safe or the police are just sitting around collecting a pay check since the community is not totally safe. (P)

Therefore

It is clear that the police are just sitting around doing nothing but collecting a pay check. (Q)

Form: All (P) are (Q), C is a (Q). Therefore C is a (P)

I was surprised to hear such views, but it did come up a few times. I spoke with some people who said that the problem with the view that the police are ineffective is that people don't "see" Police Officers enough. (C) If people could see and engage with Police Officers more often, (P), then the community could see the valuable work that Police Officers are doing.(Q) And if people could see the valuable work that Police Officers are doing,(P) then people would feel safer and be more supportive of Police Officers.(Q) It follows that if only people could see and engage with Police Officers more,(P), then people would feel safer and be more supportive of Police Officers. (Q)

I was surprised to hear such views, but it did come up a few times. I spoke with some people who said that the problem with the view that the police are ineffective is that people don't "see" Police Officers enough. (C)

If people could see and engage with Police Officers more often and if people could see the valuable work that Police Officers are doing and only people could see and engage with Police Officers more. (P)

Therefore

the community could see the valuable work that Police Officers are doing; only people could see and engage with Police Officers more, people would feel safer and be more supportive of Police Officers. (Q)

Form: All P are Q, C views were about (P). Therefore C views were on Q

Many of the complaints I read about were regarding the role of incarceration in Canada. (X)

Quite a few people felt that either correctional institutions are helpful by containing harmful individuals and offering them opportunities to reform or correctional institutions are harmful by offering a place for criminals to meet and form gangs and waste taxpayer money. (P) These people felt that Canadian correctional institutions are not helping society or inmates, so it is clear that correctional institutions are harmful by offering a place for criminals to meet and form (Q)

Quite a few people felt that either correctional institutions are helpful by containing harmful individuals and offering them opportunities to reform or correctional institutions are harmful by offering a place for criminals to meet and form gangs and waste taxpayer money.(P)

Therefore

These people felt that Canadian correctional institutions are not helping society or inmates, so it is clear that correctional institutions are harmful by offering a place for criminals to meet and form (Q)

Form: All P are Q, X complaints were on P. Therefore X complaints were on Q

Such a view is too simplistic; the reality cannot simply be reduced in this case to "either helpful or harmful." In fact, I think that the opposite view is more correct.(y)

The last couple of decades has seen a lot of positive change in the corrections system.(P) For example, there is an increase in the use of conditional sentencing and similar reforms. Many in the field reason that (Q) if there is an increase in conditional sentencing and similar reforms(P) then there will be a reduction in incarceration rates.(Q) Further, if there is a reduction in incarceration rates(P), then many wrongdoers will spend less time around prison gangs. So we can conclude that many wrongdoers are spending less time around prison gangs, not more time. (Q)

Such a view is too simplistic; the reality cannot simply be reduced in this case to "either helpful or harmful." In fact, I think that the opposite view is more correct. (y)

The last couple of decades have seen a lot of positive change in the corrections system, there is an increase in conditional sentencing and similar reforms, and there is a reduction in incarceration rates. (P)

Therefore

There is an increase in the use of conditional sentencing and similar reforms. Many in the field reason that there will be a reduction in incarceration rates, many wrongdoers will spend less time around prison gangs. So we can conclude that many wrongdoers are spending less time around prison gangs, not more time. (Q)

Form: All P are Q, Y view is on P. Therefore Y view is on Q

References

Modus Ponens, Modus Tollens. (2017). Cs.ucsb.edu. Retrieved 3 March 2017, from https://www.cs.ucsb.edu/~pconrad/cs40/lessons/logic/modusPonensModusTollens.html